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I have a UICollectionView that is working correctly. However I am trying to add section headers programmatically and I am running into a crash which I can't figure out.
My Class for the header:
class EmbeddedSectionHeaderCollectionReusableView: UICollectionReusableView {
weak var sectionHeaderLabel: UILabel!
}
My header class registration in ViewDidLoad
myCollection.register(EmbeddedSectionHeaderCollectionReusableView.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "sectionHeader")
My header implementation for section size definition
// header section size. needed for implementation.
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width:collectionView.frame.size.width, height:30.0)
}
The viewForSupplementaryElementOfKind code
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if let sectionHeader = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "sectionHeader", for: indexPath) as? EmbeddedSectionHeaderCollectionReusableView {
print("header should be showing")
sectionHeader.sectionHeaderLabel.text = "Hello, World"
return sectionHeader
}
return UICollectionReusableView()
}
The crash happens at "sectionHeader.sectionHeaderLabel.text = "Hello, World"" saying that sectionHeader is nil. My gut tells me it's because I am not initializing the header class correctly. Could that be it?
You need to add init
class EmbeddedSectionHeaderCollectionReusableView : UICollectionReusableView {
var sectionHeaderLabel: UILabel!
override init(frame: CGRect) {
super.init(frame: frame)
sectionHeaderLabel = UILabel(frame: CGRect(x: 0, y: 0, width: frame.size.width, height: frame.size.height))
self.addSubview(sectionHeaderLabel)
}
}
I have a collectionView with 2 sections. The frame of the first section will depend on the number of cells inside of it. Since the total number of cells (firstSectionData.count) in the first section will vary I need to find the CGPoint for the Second Section. I specifically need to find out the x/y values of where the second section begins.
The frame will also be suffice because I can extract them from there. How can I find this out?
var cv: UICollectionView!
let firstSectionCell = "FirstSectionCell"
let secondSectionCell = "SecondSectionCell"
let secondSectionHeaderView = "SecondSectionHeaderView"
let firstSectionData = [String]()
let secondSectionData = [String]()
let cellHeight: CGFloat = 50
let headerHeight: CGFloat = 60
override func viewDidLoad() {
super.viewDidLoad()
let layout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsetsMake(0, 0, 0, 0)
layout.scrollDirection = .horizontal
cv = UICollectionView(frame: view.frame, collectionViewLayout: layout)
cv.delegate = self ; cv.dataSource = self
cv.register(FirstSectionCell.self, forCellWithReuseIdentifier: firstSectionCell)
cv.register(SecondSectionCell.self, forCellWithReuseIdentifier: secondSectionCell)
cv.register(SecondSectionHeaderView.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: secondSectionHeaderView)
view.addSubview(cv)
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 2
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if section == 0{
return firstSectionData.count // varies
}
return secondSectionData.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.section == 0{
return firstSectionCell = collectionView.dequeueReusableCell(withReuseIdentifier: self.firstSectionCell, for: indexPath) as! FirstSectionCell
}
return secondSectionCell = collectionView.dequeueReusableCell(withReuseIdentifier: self.secondSectionCell, for: indexPath) as! SecondSectionCell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: self.cellHeight) // height is 50
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let headerView: UICollectionReusableView?
if kind == UICollectionElementKindSectionHeader{
let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: self.secondSectionHeaderView, for: indexPath) as! SecondSectionHeaderView
headerView = header
}
return headerView!
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
if section == 0{
return CGSize.zero // the first section doesn't have a header
}
return CGSize(width: view.frame.width, height: self.headerHeight) // header height is 60 for the second section
}
This type of information is kept by the collection view's layout manager. The collection view provides two convenience methods:
layoutAttributesForItem(at:)
and:
layoutAttributesForSupplementaryElement(ofKind:at:)
These return a value of UICollectionViewLayoutAttributes?. This in turn has properties such as frame and others.
If you want the frame of a specific item in a collection view you would do:
let frame = collectionView.layoutAttributesForItem(at: someIndexPath)?.frame
If you want the frame of a section header in a collection view you would do:
let frame = collectionView.layoutAttributesForSupplementaryElement(ofKind: UICollectionElementKindSectionHeader, at: someSectionIndexPath)
To get the position of a UICollectionViewCell relative to the view, in which it's located (e.g. relative to your visible area):
if let theAttributes = collectionView.layoutAttributesForItem(at: IndexPath(item: 1, section: 0)) {
let cellFrameInSuperview = collectionView.convert(theAttributes.frame, to: collectionView.superview)
print("X of Cell is: \(cellFrameInSuperview.origin.x)")
}
My header seems not showing up even I already registered programmatically in UICollectionViewFlowLayout. Just blank.
My code
override func viewDidLoad() {
super.viewDidLoad()
UICollectionReusableViewlet layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
layout.itemSize = CGSize(width: 117, height: 117)
layout.minimumLineSpacing = 1
collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
collectionView!.dataSource = self
collectionView!.delegate = self
collectionView!.registerClass(EventHeaderView.self, forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: "MyHeaderView");
collectionView!.registerClass(EventDetailCollectionViewCell.self, forCellWithReuseIdentifier:"MyCollectionViewCell")
collectionView!.backgroundColor = UIColor.blackColor()
self.view.addSubview(collectionView!)
}
func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
switch kind {
//2
case UICollectionElementKindSectionHeader:
//3
let headerView =
collectionView.dequeueReusableSupplementaryViewOfKind(kind,
withReuseIdentifier: "HeaderView",
forIndexPath: indexPath)
as! EventHeaderView
headerView.lblName.text = "Anniversary"
headerView.lblDescription.text = "Venue"
return headerView
default:
//4
assert(false, "Unexpected element kind")
}
}
Digging deeper from Ryan Lee's answer:
public func collectionView(_:UICollectionView, layout: UICollectionViewLayout, referenceSizeForHeaderInSection: Int) -> CGSize
{
if referenceSizeForHeaderInSection > 0 {
return CGSize.zero
}
return CGSize(width:0, height:50)
}
in case you have headers only for some sections, but not all of them
Assign datasource, delegate from UICollectionView to UIViewController.
Add custom UICollectionView class and assign it to UICollectionViewCell in storyboard. Also assign an identifier.
Set section header in inspector. (Image)
A header cell will be generated in collection view. Add another UICollectionViewCell class and assign this class to that cell. Also set an identifier.
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int{
return 9
}
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("customCell", forIndexPath: indexPath) as! CustomCollectionViewCell
cell.counterLabel.text = "\(indexPath.item)"
return cell
}
func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
let headerView =
collectionView.dequeueReusableSupplementaryViewOfKind(kind,withReuseIdentifier: "headerCell", forIndexPath: indexPath) as! HeaderCollectionViewCell
return headerView
default:
assert(false, "Unexpected element kind")
}
}
Here is link to github project.
Make sure you add this line in the layout:
layout.headerReferenceSize = CGSize(width:0, height:50)
How to make both header and footer in collection view in swift ?
I'm trying to combine a header and a footer together but it keep crashing, I couldn't find swift tutorial to understand it.
I don't how to return supplementary view for both rather just one .
I set them both on the storyboard (class + identifier )
override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
//#warning Incomplete method implementation -- Return the number of sections
return 2
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
//#warning Incomplete method implementation -- Return the number of items in the section
return 10
}
override func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
var header: headerCell!
var footer: footerCell!
if kind == UICollectionElementKindSectionHeader {
header =
collectionView.dequeueReusableSupplementaryViewOfKind(kind,
withReuseIdentifier: "header", forIndexPath: indexPath)
as? headerCell
}
return header
}
Error:
UICollectionElementKindCell with identifier one - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> profileCC {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("one", forIndexPath: indexPath) as! profileCC
// Configure the cell
return cell
}
override func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
let headerView = collectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: "header", forIndexPath: indexPath) as! headerCell
headerView.backgroundColor = UIColor.blueColor();
return headerView
case UICollectionElementKindSectionFooter:
let footerView = collectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: "footer", forIndexPath: indexPath) as! footerCell
footerView.backgroundColor = UIColor.greenColor();
return footerView
default:
assert(false, "Unexpected element kind")
}
}
I hope someone will help.
You can make an UICollectionViewController to handle the UICollectionView and in Interface Builder activate the Footer and Header sections, then you can use the following method for preview in you UICollectionView the two sections added :
override func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionView.elementKindSectionHeader:
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "Header", for: indexPath)
headerView.backgroundColor = UIColor.blue
return headerView
case UICollectionView.elementKindSectionFooter:
let footerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "Footer", for: indexPath)
footerView.backgroundColor = UIColor.green
return footerView
default:
assert(false, "Unexpected element kind")
}
}
In the above code I put the identifier for the footer and header as Header and Footer for example, you can do it as you want. If you want to create a custom header or footer then you need to create a subclass of UICollectionReusableView for each and customize it as you want.
You can register your custom footer and header classes in Interface Builder or in code with:
registerClass(myFooterViewClass, forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withReuseIdentifier: "myFooterView")
Updated for Swift 3+
Step 1:
In your view controller class, register the class to be used as a header, footer, or both:
let collectionViewHeaderFooterReuseIdentifier = "MyHeaderFooterClass"
Step 2:
If using a xib, use:
collectionView.register(UINib(nibName: collectionViewHeaderFooterReuseIdentifier bundle: nil), forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier:collectionViewHeaderFooterReuseIdentifier)
collectionView.register(UINib(nibName: collectionViewHeaderFooterReuseIdentifier bundle: nil), forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withReuseIdentifier:collectionViewHeaderFooterReuseIdentifier)
If not using a xib:
collectionView.register(MyHeaderFooterClass.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: collectionViewHeaderFooterReuseIdentifier)
collectionView.register(MyHeaderFooterClass.self, forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withReuseIdentifier: collectionViewHeaderFooterReuseIdentifier)
Step 3:
Create a custom header/footer class, implementation looks like:
import UIKit
class MyHeaderFooterClass: UICollectionReusableView {
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.purple
// Customize here
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
Step 4: If not using a xib, ignore
Create a new empty xib: "File --> New File --> Empty".
Name it the exact same name as the class. In this example: "MyHeaderFooterClass"
Add a collection reusable view to the xib.
Click on that object, select the Identity Inspector and change the class of that object to "MyHeaderFooterClass".
Step 5:
- Support that new cell in your collection view via delegate method:
func collectionView(_ collectionView: UICollectionView,
viewForSupplementaryElementOfKind kind: String,
at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: collectionViewHeaderFooterReuseIdentifier, for: indexPath)
headerView.backgroundColor = UIColor.blue
return headerView
case UICollectionElementKindSectionFooter:
let footerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: collectionViewHeaderFooterReuseIdentifier, for: indexPath)
footerView.backgroundColor = UIColor.green
return footerView
default:
assert(false, "Unexpected element kind")
}
}
Step 6:
Handle size / make it appear:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.width, height: 180.0)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return CGSize(width: 60.0, height: 30.0)
}
In addition to all answers above
To activate the Footer and Header sections
Select your collection then select Attributes inspector and check on the Footer and Header sections
like in photo
Just to complement the remaining answers, don't forget to allocate space for your header/footer views, otherwise collectionView:viewForSupplementaryElementOfKind:atIndexPath won't be called.
Do so by implementing collectionView:layout:referenceSizeForHeaderInSection in your collectionView datasource.
After using #mobilecat code you should use this function to make the header and footer appear
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.width, height: 180.0)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return CGSize(width: 60.0, height: 30.0)
}
Xcode 11+ & iOS 13+
I am using Xib for creating Header & Footer Views
Create a Xibs and Class File For Header & Footer like this (Same as Footer class) & also create xib views for both
class HeaderViewCV: UICollectionReusableView {
}
Register Xib Cells like this
collectionView.register(UINib(nibName: "HeaderViewCV", bundle: nil), forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "HeaderViewCV") //elementKindSectionFooter for footerview
Header & Footer View Methods
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionView.elementKindSectionHeader:
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "HeaderViewCV", for: indexPath)
return headerView
case UICollectionView.elementKindSectionFooter:
let footerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "FooterViewCV", for: indexPath)
return footerView
default:
assert(false, "Unexpected element kind")
}
}
For View Height Method for both
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: self.collectionView.frame.width, height: 55)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return CGSize(width: self.collectionView.frame.width, height: 67)
}
Done all the necessary requirement for Header & Footer in CollectionView is ready
Solution
class CustomFlowLayout: UICollectionViewFlowLayout {
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
let attributesForElementsInRect = super.layoutAttributesForElements(in: rect)
var newAttributesForElementsInRect = [UICollectionViewLayoutAttributes]()
for attributes in attributesForElementsInRect! {
if !(attributes.representedElementKind == UICollectionElementKindSectionHeader
|| attributes.representedElementKind == UICollectionElementKindSectionFooter) {
// cells will be customise here, but Header and Footer will have layout without changes.
}
newAttributesForElementsInRect.append(attributes)
}
return newAttributesForElementsInRect
}
}
class YourViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let headerNib = UINib.init(nibName: "HeaderCell", bundle: nil)
collectionView.register(headerNib, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "HeaderCell")
let footerNib = UINib.init(nibName: "FooterCell", bundle: nil)
collectionView.register(footerNib, forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withReuseIdentifier: "FooterCell")
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "HeaderCell", for: indexPath) as! HeaderCell
return headerView
case UICollectionElementKindSectionFooter:
let footerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "FooterCell", for: indexPath) as! FooterCell
return footerView
default:
return UICollectionReusableView()
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.width, height: 45)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.width, height: 25)
}
}
if you need to keep empty spaces for header and footer make an extension of UICollectionViewDelegateFlowLayout and use this code to set header or footer accordingly.
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
let footerValue = 150
let headerValue = 150
collectionView.contentInset = UIEdgeInsets(top: headerValue, left: 0, bottom: footerValue, right: 0)
}
Note that your viewController must implement UICollectionViewDelegateFlowLayout or these methods won't get called
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
}
following #mobilecat detailed answer, if you are using compositional collection view, add these lines when creating the layout:
let headerSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .estimated(44))
let headerElement = NSCollectionLayoutBoundarySupplementaryItem(layoutSize: headerSize, elementKind: UICollectionView.elementKindSectionHeader, alignment: .top)
and set the headerElement to your section like this:
let section = NSCollectionLayoutSection(group: group)
section.boundarySupplementaryItems = [headerElement]
The full code snippet is:
private func createCompositionalLayout() -> UICollectionViewCompositionalLayout {
let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalHeight(1.0),
heightDimension: .fractionalHeight(0.2))
let item = NSCollectionLayoutItem(layoutSize: itemSize)
let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
heightDimension: .fractionalWidth(1.0))
let group = NSCollectionLayoutGroup.vertical(layoutSize: groupSize, subitems: [item])
let headerSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .estimated(44))
let headerElement = NSCollectionLayoutBoundarySupplementaryItem(layoutSize: headerSize, elementKind: UICollectionView.elementKindSectionHeader, alignment: .top)
let section = NSCollectionLayoutSection(group: group)
section.boundarySupplementaryItems = [headerElement]
let layout = UICollectionViewCompositionalLayout(section: section)
return layout
}
I am struggling trying to do multiple sections in my collection view with a header for each section. I don't know Obj-C and I've found a good amount of tutorials for it, but haven't been able to figure out how to convert it into Swift.
All my data is static so all I need is some sort of array or dictionary that I can use to create the multiple sections. I already have a collection view with 1 section working, so if you have any insight or code for multiple sections that'd be helpful.
I know how to set multiple sections using
func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return sectionData.count
}
I think the main thing I need help with is implementing this func
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell { }
and setting up the data!
UICollectionView and UITableView are almost exactly the same, so if you know how to do multiple sections in a UITableView in Swift, your help is also appreciated
The cellForItemAtIndexPath function handles populating each section with cells, it does not handle sections or supplementaryViews, and therefore is not the main thing you need help with when it comes to creating section headers.
the method you need to implement is viewForSupplementaryElementOfKind. Its signature is:
func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {}
Assuming that your collectionView is working correctly for 1 section (you have properly filled out the body of your cellForItemAtIndexPath and your sectionData array properly reflects the number of sections you want to display), you should be able to implement section headers using the following pointers:
Along with cells, UICollectionView also supports "supplementary" view objects, typically used for headers or footers. These Supplementary Views act very similarly to UICollectionViewCell objects. In the same way that cellForItemAtIndexPath handles cells, The viewForSupplementaryElementOfKind function handles supplementary views.
To implement it, you will need to first prepare your ViewController to do so. First edit your layout object to reflect an appropriate header size, that each header will adhere to:
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.headerReferenceSize = CGSize(width: self.view.frame.size.width, height: 30)
NOTE: I am using a UICollectionViewFlowLayout
Next, if you haven't already done so, create a SectionHeader class that defines each section header object, so you can then register that class with your collectionView object like so:
collectionView!.registerClass(SectionHeaderView.self, forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: "SectionHeaderView");
Here, the first and third argument passed in are the same as a UICollectionViewCell Class registration, the first argument in this method is the reference to the section header class you created. The third is the reuse identifier for the Supplementary View.
The second argument is specific to Supplementary Views, this sets the kind of the SupplementaryView, which in this case is a header, the constant string provided by the UICollectionViewFlowLayout class UICollectionElementKindSectionHeader is used for it. If you noticed the parameters on the viewForSupplementaryElementOfKind, this kind is later passed in as the kind: String parameter.
Fill in the body of your viewForSupplementaryElementOfKind the same way you would for a cellForItemAtIndexPath function-- Using the dequeueReusableSupplementaryViewOfKind method to create a SectionHeader object, then set any attributes as necessary (labels, colors, etc.) and finally return the header object.
Hope this helps!!
Reference points:
https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UICollectionViewDataSource_protocol/index.html#//apple_ref/occ/intfm/UICollectionViewDataSource/
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UICollectionViewFlowLayout_class/index.html#//apple_ref/c/data/UICollectionElementKindSectionHeade
Define your UICollectionViewCell which will be your Header view of kind UICollectionElementKindSectionHeader - In my case I have two headers - OfferHeaderCell and APRHeaderCell defined as below:
verticalCollectionView.register(UINib(nibName: "OfferHeaderCell", bundle: nil), forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: "OfferHeaderCell")
verticalCollectionView.register(UINib(nibName: "APRHeaderCell", bundle: nil), forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: "APRHeaderCell")
Go ahead and return a header for each section and then set the size of the section header to have a size of zero in this UICollectionViewDelegateFlowLayout function
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
if(section==0) {
return CGSize.zero
} else if (section==1) {
return CGSize(width:collectionView.frame.size.width, height:133)
} else {
return CGSize(width:collectionView.frame.size.width, height:100)
}
}
Important to define the viewForSupplementaryElementOfKind for two different sections as below:
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
var reusableview = UICollectionReusableView()
if (kind == UICollectionElementKindSectionHeader) {
let section = indexPath.section
switch (section) {
case 1:
let firstheader: OfferHeaderCell = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "OfferHeaderCell", for: indexPath) as! OfferHeaderCell
reusableview = firstheader
case 2:
let secondHeader: APRHeaderCell = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "APRHeaderCell", for: indexPath) as! APRHeaderCell
reusableview = secondHeader
default:
return reusableview
}
}
return reusableview
}
And lastly the Datasource,
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 3
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if (section==2) {
return 2
}
return 0
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = verticalCollectionView.dequeueReusableCell(withReuseIdentifier: "ReviseOfferCell", for: indexPath)
cell.backgroundColor = UIColor.white
return cell
}
Note: Don't forgot to add UICollectionFlowLayout as below:
// MARK: UICollectionViewDelegateFlowLayout
extension MakeAnOfferController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if indexPath.item == 0 {
return CGSize(width: self.view.frame.size.width, height: 626.0)
}
return CGSize()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
if(section==0) {
return CGSize.zero
} else if (section==1) {
return CGSize(width:collectionView.frame.size.width, height:133)
} else {
return CGSize(width:collectionView.frame.size.width, height:100)
}
}
}
Here is the code that worked for me
create the header cell. To do which i created a custom cell class and a nib to do the customization of the cell in the graphic editor
In viewDidLoad add the following
self.collectionView?.registerNib(UINib(nibName: "KlosetCollectionHeaderViewCell", bundle: nil), forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: "HeaderCell")
Then you add the delegate function
override func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> KlosetCollectionHeaderViewCell {
let headerCell = collectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: "HeaderCell", forIndexPath: indexPath) as? KlosetCollectionHeaderViewCell
return headerCell!
}
This will put the HeaderCell in the SectionView of the PFCollectionView
The controls that show in the cell you add them to the xib file as well as the outlets and actions
Here is the code to achieve UICollection multiple sections made programmatically using SnapKit
ViewController
import SnapKit
import UIKit
class SelectIconViewController: GenericViewController<SelectIconView>, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
weak var delegate: SpaceAddViewController?
struct Section {
var sectionName : String
var rowData : [String]
}
var sections : [Section]!
init(delegate: SpaceAddViewController) {
self.delegate = delegate
super.init()
}
public required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func viewDidLoad() {
super.viewDidLoad()
contentView.closeButton.addTarget(self, action: #selector(self.back), for: .touchUpInside)
self.sections = [
Section(sectionName: "SPACES", rowData: ["Air Conditioner", "Apple HomePod"]),
Section(sectionName: "HOME APPLIANCES", rowData: ["Ceiling Fan", "Fan", "Desk Lamp", "Iron", "PC on Desk", "Plug", "Power Strip", "Lorem", "Lorem", "Lorem", "Lorem"]),
]
self.contentView.collectionView.dataSource = self
self.contentView.collectionView.delegate = self
self.contentView.collectionView.register(SelectIconHeaderViewCell.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: SelectIconHeaderViewCell.reuseId)
self.contentView.collectionView.register(SelectIconViewCell.self, forCellWithReuseIdentifier: SelectIconViewCell.reuseId)
}
#objc func back() {
self.dismiss(animated: true, completion: nil)
}
#objc func dismissKeyboard() {
view.endEditing(true)
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return self.sections.count
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.sections[section].rowData.count
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 0, left: 20, bottom: 0, right: 20)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: getTotalSpacing(), height: getTotalSpacing())
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
let screenSize = UIScreen.main.bounds
let screenWidth = screenSize.width-40
return CGSize(width: screenWidth-80, height: 50)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
// MARK: Cells
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = self.contentView.collectionView.dequeueReusableCell(withReuseIdentifier: SelectIconViewCell.reuseId, for: indexPath as IndexPath) as! SelectIconViewCell
cell.initializeUI()
cell.createConstraints()
cell.setValues(iconName: "", label: self.sections[indexPath.section].rowData[indexPath.row])
return cell
}
// MARK: Header
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionView.elementKindSectionHeader:
let cell = self.contentView.collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: SelectIconHeaderViewCell.reuseId, for: indexPath) as! SelectIconHeaderViewCell
cell.initializeUI()
cell.createConstraints()
cell.setTitle(title: self.sections[indexPath.section].sectionName)
return cell
default: fatalError("Unexpected element kind")
}
}
func getTotalSpacing() -> CGFloat {
let screenSize = UIScreen.main.bounds
let screenWidth = screenSize.width
let numberOfItemsPerRow:CGFloat = 3
let spacingBetweenCells:CGFloat = 0
let sideSpacing:CGFloat = 20
return (screenWidth-(2 * sideSpacing) - ((numberOfItemsPerRow - 1) * spacingBetweenCells))/numberOfItemsPerRow
}
}
The View:
import UIKit
import SnapKit
class SelectIconView: GenericView {
private let contentView = UIView(frame: .zero)
private (set) var closeButton = UIButton(type: .system)
internal var collectionView: UICollectionView!
internal override func initializeUI() {
self.backgroundColor = Theme.Color.white
self.addSubview(contentView)
contentView.addSubview(closeButton)
if let image = UIImage(named: "icon_close") {
image.withRenderingMode(.alwaysTemplate)
closeButton.setImage(image, for: .normal)
closeButton.tintColor = Theme.Color.text
}
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
layout.minimumInteritemSpacing = 0
collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
contentView.addSubview(collectionView)
collectionView.backgroundColor = Theme.Color.background
}
internal override func createConstraints() {
contentView.snp.makeConstraints { (make) in
make.top.equalTo(safeAreaLayoutGuide.snp.top).priority(750)
make.left.right.equalTo(self).priority(1000)
make.bottom.equalTo(safeAreaLayoutGuide.snp.bottom)
}
closeButton.snp.makeConstraints { make in
make.right.equalTo(safeAreaLayoutGuide.snp.right).offset(-10)
make.top.equalTo(contentView.snp.top).offset(10)
make.height.equalTo(40)
make.width.equalTo(40)
}
collectionView.snp.makeConstraints { make in
make.top.equalTo(closeButton.snp.bottom).offset(20)
make.left.equalTo(safeAreaLayoutGuide.snp.left)
make.right.equalTo(safeAreaLayoutGuide.snp.right)
make.bottom.equalTo(contentView.snp.bottom)
}
}
}
The customized section Header
import UIKit
class SelectIconHeaderViewCell: UICollectionViewCell {
internal let mainView = UIView()
internal var title = UILabel()
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func initializeUI() {
self.backgroundColor = UIColor.clear
self.addSubview(mainView)
mainView.backgroundColor = UIColor.clear
mainView.addSubview(title)
title.text = "Pick nameA"
title.font = Theme.Font.body()
title.textAlignment = .left
title.textColor = Theme.Color.text
title.numberOfLines = 1
}
internal func createConstraints() {
mainView.snp.makeConstraints { (make) in
make.edges.equalTo(self)
}
title.snp.makeConstraints { (make) in
make.centerY.equalTo(mainView.snp.centerY)
make.leading.equalTo(mainView).offset(20)
make.trailing.equalTo(mainView).offset(-20)
}
}
func setTitle(title: String) {
self.title.text = title
}
static var reuseId: String {
return NSStringFromClass(self)
}
}
And the cell:
import UIKit
class SelectIconViewCell: UICollectionViewCell {
internal let mainView = UIView()
internal var iconImage = UIImageView()
internal var label = UILabel()
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func initializeUI() {
self.backgroundColor = UIColor.clear
self.addSubview(mainView)
mainView.backgroundColor = UIColor.clear
mainView.layer.masksToBounds = true
mainView.layer.borderColor = Theme.Color.backgroundCell.cgColor
mainView.layer.borderWidth = 1.0
mainView.addSubview(iconImage)
iconImage.image = UIImage(named: "icons8-air-conditioner-100")
mainView.addSubview(label)
label.font = Theme.Font.footnote()
label.textAlignment = .center
label.textColor = Theme.Color.textInfo
label.numberOfLines = 1
}
internal func createConstraints() {
mainView.snp.makeConstraints { (make) in
make.edges.equalTo(self)
}
iconImage.snp.makeConstraints { (make) in
make.center.equalTo(mainView.snp.center)
make.width.height.equalTo(20)
}
label.snp.makeConstraints { (make) in
make.top.equalTo(iconImage.snp.bottom).offset(6)
make.leading.equalTo(mainView).offset(5)
make.trailing.equalTo(mainView).offset(-5)
}
}
func setValues(iconName: String, label: String) {
//self.iconImage.image = UIImage(named: iconName)
self.label.text = label
}
static var reuseId: String {
return NSStringFromClass(self)
}
}
After creating and registering custom header (and/or footers), you can easily specify different header (or footers for that matter) for different section. Here's an example:
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
let section = indexPath.section
switch section {
case 0:
let userHeader = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: userHeaderReuseIdentifier, for: indexPath) as! UserHeader
return userHeader
default:
let postHeader = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: postHeaderReuseIdentifier, for: indexPath) as! PostHeader
return postHeader
}
case UICollectionElementKindSectionFooter:
let userFooter = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: userFooterReuseIdentifier, for: indexPath) as! UserFooter
return userFooter
default:
return UICollectionReusableView()
}
}
Make sure to specify correct number of sections, too:
override func numberOfSections(in collectionView: UICollectionView) -> Int {
return 2
}
Worked solution for Swift-3
i)Create Custom Cell && corresponding xib
class SectionHeaderView: UICollectionViewCell {
static let kReuseIdentifier = "SectionHeaderView"
#IBOutlet weak var invitationsSectionHeader: UILabel!
#IBOutlet weak var numberOfPerson: UILabel!
}
ii)Register Custom Collection View Cell for HeaderView
self.collectionView.register(UINib(nibName: SectionHeaderView.kReuseIdentifier, bundle: nil), forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: SectionHeaderView.kReuseIdentifier)
iii)Call delegate function to render Custom Header View.
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
let headerView: SectionHeaderView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: SectionHeaderView.kReuseIdentifier, for: indexPath) as! SectionHeaderView
return headerView
default:
return UICollectionReusableView()
}
}
iv)Mention Height of the Custom Header View
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width:collectionView.frame.size.width, height:30)
}
#Tarun's answer worked a treat for me; I was missing collectionView(_:layout:referenceSizeForHeaderInSection:), which I needed since sometimes the data to be shown would be sorted and sometimes not.
In addition, pinning the section header to the top of the screen (as in the table view Apple's Address Book app) was accomplished by adding the following to viewDidLoad() in the UICollectionViewController:
if let flowLayout = collectionViewLayout as? UICollectionViewFlowLayout {
flowLayout.sectionHeadersPinToVisibleBounds = true
}