I have a vertically scrolling UICollectionView that uses a subclass of UICollectionViewFlowLayout to try and eliminate inter-item spacing. This would result in something that looks similar to a UITableView, but I need the CollectionView for other purposes. There is a problem in my implementation of the FlowLayout subclass that causes cells to disappear when scrolling fast. Here is the code for my FlowLayout subclass:
EDIT: See Comments For Update
class ListLayout: UICollectionViewFlowLayout {
override func layoutAttributesForElementsInRect(rect: CGRect) -> [AnyObject]? {
if var answer = super.layoutAttributesForElementsInRect(rect) {
for attr in (answer as [UICollectionViewLayoutAttributes]) {
let ip = attr.indexPath
attr.frame = self.layoutAttributesForItemAtIndexPath(ip).frame
}
return answer;
}
return nil
}
override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes! {
let currentItemAtts = super.layoutAttributesForItemAtIndexPath(indexPath) as UICollectionViewLayoutAttributes
if indexPath.item == 0 {
var frame = currentItemAtts.frame
frame.origin.y = 0
currentItemAtts.frame = frame
return currentItemAtts
}
let prevIP = NSIndexPath(forItem: indexPath.item - 1, inSection: indexPath.section)
let prevFrame = self.layoutAttributesForItemAtIndexPath(prevIP).frame
let prevFrameTopPoint = prevFrame.origin.y + prevFrame.size.height
var frame = currentItemAtts.frame
frame.origin.y = prevFrameTopPoint
currentItemAtts.frame = frame
return currentItemAtts
}
}
One other thing to note: My cells are variable height. Their height is set by overriding preferredLayoutAttributesFittingAttributes in the subclass of the custom cell:
override func preferredLayoutAttributesFittingAttributes(layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes! {
let attr: UICollectionViewLayoutAttributes = layoutAttributes.copy() as UICollectionViewLayoutAttributes
attr.frame.size = CGSizeMake(self.frame.size.width, myHeight)
return attr
}
And I set the layout's estimated size on initialization:
flowLayout.estimatedItemSize = CGSize(width: UIScreen.mainScreen().bounds.size.width, height: 60)
Here is a GIF that demonstrates this problem:
Does anybody have an idea as to what's going on? Your help is much appreciated.
Thanks!
Related
I put a WebView in a tableViewCell and I use it in a tableView. Until now everything is working fine. But I was using a fixed size for the WebViewCell. Now I want to show all the content of the WebView. I changed my code to this one in the MyTbaleView class
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
if let cell = modelCollection[collection.identifier] {
if let _ = cell as? TiteCell{
return 200
} else if let _ = cell as? myWebViewCell{
return UITableViewAutomaticDimension
}
}
func tableView(tableView: UITableView, EstimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 1000
}
and this is the xib file
myWebView Xib file
With this code the WebView become really small, a few millimeters. I tried to add this code I found in the forum to MyWebViewCell class
func webViewDidFinishLoad(webView : UIWebView) {
var frame = myWebView.frame
frame.size.height = 1
myWebView.frame = frame
let fittingSize = myWebView.sizeThatFits(CGSize(width: 0, height: 0))
frame.size = fittingSize
myWebView.frame = frame
myWebView.scrollView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0);
}
Now the webview is a little bit bigger, 1 centimeter and the width is larger than the ipad width.
As #Ramaraj T said, its a very costlier process and I to approve that you should change your design. But if you still want to continue you can do something like this.
Create a HeightConstraint for WebView in your custom cell.
// Code in cell
var webViewHeightConstraint: NSLayoutConstarint!
// Code in controller
// code cellForIndexPath
webView.tag = indexPath.row(or any unique value which can be used to calculate indexPath)
func webViewDidFinishLoad(webView : UIWebView) {
var frame = myWebView.frame
frame.size.height = 1
myWebView.frame = frame
let fittingSize = myWebView.sizeThatFits(CGSize(width: 0, height: 0))
frame.size = fittingSize
myWebView.frame = frame
myWebView.scrollView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0);
let height = myWebView.contentSize.height
let section = webView.tag
let indexPath = NSIndexPath(forRow: 0, inSection: section)
let cell = tableView.dequeCell(atIndexPath: indexPath)//
cell.webViewHeightConstraint.constant = height
cell.layoutConstraintsIfNeeded()
tableView.beginUpdates()
tableView.endUpdates()
}
How do I display selected images from the uiimagepickercontroller like the image shown. I am getting a black area on the collectionview. I'm not even sure using a horizontal uicollectionview is the best approach.
I think using horizontal UICollectionView is affordable idea.
You can make 'Add Picture Button' always located in last if you add it as footer.
To do this, subclass your UICollectionViewFlowLayout and override layoutAttributesForElementsInRect().
override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
if let layoutAttributesForElementsInRect = super.layoutAttributesForElementsInRect(rect), let collectionView = self.collectionView {
for layoutAttributes in layoutAttributesForElementsInRect {
if layoutAttributes.representedElementKind == UICollectionElementKindSectionFooter {
let section = layoutAttributes.indexPath.section
let numberOfItemsInSection = collectionView.numberOfItemsInSection(section)
if numberOfItemsInSection > 0 {
let lastCellIndexPath = NSIndexPath(forItem: max(0, numberOfItemsInSection - 1), inSection: section)
if let lastCellAttrs = self.layoutAttributesForItemAtIndexPath(lastCellIndexPath) {
var origin = layoutAttributes.frame.origin
origin.x = CGRectGetMaxX(lastCellAttrs.frame)
layoutAttributes.zIndex = 1024
layoutAttributes.frame.origin = origin
layoutAttributes.frame.size = layoutAttributes.frame.size
}
}
}
}
return layoutAttributesForElementsInRect
}
return nil
}
I have a dataset that is divided into multiple sections, however, I'd like to display this in a collectionView without breaks between sections. Here's an illustration of what I want to achieve:
Instead of:
0-0 0-1 0-2
0-3
1-0 1-1
2-0
3-0
I want:
0-0 0-1 0-2
0-3 1-0 1-1
2-0 3-0
I realize the solution likely lies with a custom UICollectionViewLayout subclass, but I'm not sure how to achieve something like this.
Thanks
You are correct that you need to subclass UICollectionViewLayout.
The essence to understand before starting is that you need to calculate at least position and size for every cell in the collection view. UICollectionViewLayout is just a structured way to provide that information. You get the structure, but you have to provide everything else yourself.
There are 4 methods you need to override:
prepare
invalidateLayout
layoutAttributesForItemAtIndexPath
layoutAttributesForElementsInRect
One trick is to cache the layout attributes in a lookup table (dictionary):
var cachedItemAttributes = [IndexPath: UICollectionViewLayoutAttributes]()
In prepare, you calculate the layout attributes for each indexPath in your collectionView:
override func prepare() {
super.prepare()
calculateAttributes()
}
In invalidateLayout you reset the cached layout attributes and recalculate them:
override func invalidateLayout() {
super.invalidateLayout()
cachedItemAttributes = [:]
calculateAttributes()
}
In layoutAttributesForItemAtIndexPath you use the lookup table to return the right layout attributes:
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
return cachedItemAttributes[indexPath]
}
In layoutAttributesForElementsInRect you filter your lookup table for the elements within the specified rect:
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
return cachedItemAttributes.filter { rect.intersects($0.value.frame) }.map { $0.value }
}
The final piece of the puzzle is the actual calculation of the layout attributes. Here I will provide only pseudo-code:
func calculateAttributes() {
// For each indexpath (you can get this from the collectionView property using numberOfSections and numberOfItems:inSection )
// calculate the frame, i.e the origin point and size of each cell in your collectionView and set it with UICollectionViewLayoutAttributes.frame
// There are many other properties on UICollectionViewLayoutAttributes that you can tweak for your layout, but frame is a good starting point from which you can start experimenting.
// Add the layout attributes to the lookup table
// end loop
}
To answer your question, here is pseudo-code to calculate the position of each cell:
// If width of cell + current width of row + spacing, insets and margins exceeds the available width
// move to next row.
// else
// cell origin.x = current width of row + interitem spacing
// cell origin.y = number of rows * (row height + spacing)
// endif
If you need your custom layout to be configurable, then either use UICollectionViewDelegateFlowLayout if the available signatures are sufficient, or define your own that inherits from UICollectionViewDelegateFlowLayout or UICollectionViewDelegate. Because your protocol inherits from UICollectionViewDelegateFlowLayout, which itself inherits from UICollectionViewDelegate, you can set it directly as the collectionView delegate in your viewcontroller. In your custom collection view layout you just need to cast the delegate from UICollectionViewDelegate to your custom protocol to use it. Remember to handle cases where the casting fails or where the protocol methods are not implemented by the delegate.
I found that for me, Marmoy's answer is missing one additional element:
overriding collectionViewContentSize.
Otherwise, depending on the size of your collectionView, you may get a call to layoutAttributesForElements(in rect: CGRect) which has a zero width or height, which will miss many of the cells. This is especially true if you're trying to dynamically size items in the collection view.
So a more complete version of Marmoy's answer would be:
import UIKit
class NoBreakSectionCollectionViewLayout: UICollectionViewLayout {
var cachedItemAttributes = [IndexPath: UICollectionViewLayoutAttributes]()
var cachedContentSize = CGSize.zero
override func prepare() {
super.prepare()
calculateAttributes()
}
override func invalidateLayout() {
super.invalidateLayout()
cachedItemAttributes = [:]
calculateAttributes()
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
return cachedItemAttributes[indexPath]
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
return cachedItemAttributes.filter { rect.intersects($0.value.frame) }.map { $0.value }
}
override var collectionViewContentSize: CGSize {
return cachedContentSize
}
func calculateAttributes() {
var y = CGFloat(0)
var x = CGFloat(0)
var lastHeight = CGFloat(0)
let xSpacing = CGFloat(5)
let ySpacing = CGFloat(2)
if let collectionView = collectionView, let datasource = collectionView.dataSource, let sizeDelegate = collectionView.delegate as? UICollectionViewDelegateFlowLayout {
let sections = datasource.numberOfSections?(in: collectionView) ?? 1
for section in 0..<sections {
for item in 0..<datasource.collectionView(collectionView, numberOfItemsInSection: section){
let indexPath = IndexPath(item: item, section: section)
let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
if let size = sizeDelegate.collectionView?(collectionView, layout: self, sizeForItemAt: indexPath) {
if x > 0 && (x + size.width + xSpacing) > collectionView.bounds.width {
y += size.height + ySpacing
x = CGFloat(0)
}
attributes.frame = CGRect(x: x, y: y, width: size.width, height: size.height)
lastHeight = size.height
x += size.width + xSpacing
}
cachedItemAttributes[indexPath] = attributes
}
}
cachedContentSize = CGSize(width: collectionView.bounds.width, height: y + lastHeight)
}
}
}
Additionally, it's important for your delegate to implement UICollectionViewDelegateFlowLayout in the example above... Alternately, you can just calculate item sizes in the Layout if you know them without knowing about the cell content.
I am using a collection view to display datas fetched from the web service. I also have a supplementary view (header), which contains a UIImageView and a label. The UIImageView animates to show an array of images. The problem arises when I scroll the view. When the header is hidden and then scrolled up showing it, the app freezes briefly.
func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
let headerView = categoryView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "bannerHeader", forIndexPath: indexPath) as! HeaderBanner
print("Got into header")
print("THE NUMBER OF AD ITEMS IS: \(self.adItems.count)")
var sliderImages = [UIImage]()
var imageAddressArray = [String]()
if(self.adItems.count>0) {
print("AD ITEMS IS GREATER THAN 0")
for i in 0..<self.adItems.count {
imageAddressArray.append(URLEncoder.encodeURL(self.adItems[i].filePath!))
}
dispatch_async(dispatch_get_main_queue(), {
AdsImageDataFetch.fetchImageData(imageAddressArray) { result -> () in
sliderImages = result
self.animateImageView(headerView.bannerImage, images: sliderImages, label: headerView.bannerLabel)
}
})
}
return headerView
}
I think I have done this correctly. So, I was wondering if there is any way to not load the header when the scrolling takes place. New to iOS and Swift.
Since I couldn't find a solution I used a floating header view instead so that it wouldn't get refreshed every time on scroll. For other's who want to use the floating header view in Swift 2.0. Here is the code:
class StickyHeaderFlowLayout: UICollectionViewFlowLayout {
override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
// Return true so we're asked for layout attributes as the content is scrolled
return true
}
override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
// Get the layout attributes for a standard UICollectionViewFlowLayout
var elementsLayoutAttributes = super.layoutAttributesForElementsInRect(rect)
if elementsLayoutAttributes == nil {
return nil
}
// Define a struct we can use to store optional layout attributes in a dictionary
struct HeaderAttributes {
var layoutAttributes: UICollectionViewLayoutAttributes?
}
var visibleSectionHeaderLayoutAttributes = [Int : HeaderAttributes]()
// Loop through the layout attributes we have
for (index, layoutAttributes) in (elementsLayoutAttributes!).enumerate() {
let section = layoutAttributes.indexPath.section
switch layoutAttributes.representedElementCategory {
case .SupplementaryView:
// If this is a set of layout attributes for a section header, replace them with modified attributes
if layoutAttributes.representedElementKind == UICollectionElementKindSectionHeader {
let newLayoutAttributes = layoutAttributesForSupplementaryViewOfKind(UICollectionElementKindSectionHeader, atIndexPath: layoutAttributes.indexPath)
elementsLayoutAttributes![index] = newLayoutAttributes!
// Store the layout attributes in the dictionary so we know they've been dealt with
visibleSectionHeaderLayoutAttributes[section] = HeaderAttributes(layoutAttributes: newLayoutAttributes)
}
case .Cell:
// Check if this is a cell for a section we've not dealt with yet
if visibleSectionHeaderLayoutAttributes[section] == nil {
// Stored a struct for this cell's section so we can can fill it out later if needed
visibleSectionHeaderLayoutAttributes[section] = HeaderAttributes(layoutAttributes: nil)
}
case .DecorationView:
break
}
}
// Loop through the sections we've found
for (section, headerAttributes) in visibleSectionHeaderLayoutAttributes {
// If the header for this section hasn't been set up, do it now
if headerAttributes.layoutAttributes == nil {
let newAttributes = layoutAttributesForSupplementaryViewOfKind(UICollectionElementKindSectionHeader, atIndexPath: NSIndexPath(forItem: 0, inSection: section))
elementsLayoutAttributes!.append(newAttributes!)
}
}
return elementsLayoutAttributes
}
override func layoutAttributesForSupplementaryViewOfKind(elementKind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes? {
// Get the layout attributes for a standard flow layout
let attributes = super.layoutAttributesForSupplementaryViewOfKind(elementKind, atIndexPath: indexPath)
// If this is a header, we should tweak it's attributes
if elementKind == UICollectionElementKindSectionHeader {
if let fullSectionFrame = frameForSection(indexPath.section) {
let minimumY = max(collectionView!.contentOffset.y + collectionView!.contentInset.top, fullSectionFrame.origin.y)
let maximumY = CGRectGetMaxY(fullSectionFrame) - headerReferenceSize.height - collectionView!.contentInset.bottom
attributes!.frame = CGRect(x: 0, y: min(minimumY, maximumY), width: collectionView!.bounds.size.width, height: headerReferenceSize.height)
attributes!.zIndex = 1
}
}
return attributes
}
// MARK: Private helper methods
private func frameForSection(section: Int) -> CGRect? {
// Sanity check
let numberOfItems = collectionView!.numberOfItemsInSection(section)
if numberOfItems == 0 {
return nil
}
// Get the index paths for the first and last cell in the section
let firstIndexPath = NSIndexPath(forRow: 0, inSection: section)
let lastIndexPath = numberOfItems == 0 ? firstIndexPath : NSIndexPath(forRow: numberOfItems - 1, inSection: section)
// Work out the top of the first cell and bottom of the last cell
let firstCellTop = layoutAttributesForItemAtIndexPath(firstIndexPath)!.frame.origin.y
let lastCellBottom = CGRectGetMaxY(layoutAttributesForItemAtIndexPath(lastIndexPath)!.frame)
// Build the frame for the section
var frame = CGRectZero
frame.size.width = collectionView!.bounds.size.width
frame.origin.y = firstCellTop
frame.size.height = lastCellBottom - firstCellTop
// Increase the frame to allow space for the header
frame.origin.y -= headerReferenceSize.height
frame.size.height += headerReferenceSize.height
// Increase the frame to allow space for an section insets
frame.origin.y -= sectionInset.top
frame.size.height += sectionInset.top
frame.size.height += sectionInset.bottom
return frame
}
}
By default (i.e., with a vertical scrolling direction), the UICollectionViewFlowLayout lays out cells by starting at the top-left, going from left to right, until the row is filled, and then proceeds to the next line down. Instead, I would like it to start at the bottom-left, go from left to right, until the row is filled, and then proceed to the next line up.
Is there a straightforward way to do this by subclassing UIScrollViewFlowLayout, or do I basically need to re-implement that class from scratch?
Apple's documentation on subclassing flow layout suggests that I only need to override and re-implement my own version of layoutAttributesForElementsInRect:, layoutAttributesForItemAtIndexPath:, and collectionViewContentSize. But this does not seem straightforward. Since UICollectionViewFlowLayout does not expose any of the grid layout calculations it makes internally in prepareLayout, I need to deduce all the layout values needed for the bottom-to-top layout from the values it generates for a top-to-bottom layout.
I am not sure this is possible. While I can re-use its calculations about which groups of items get put on the same rows, I will need to calculate new y offsets. And to make my calculations I will need information about all the items, but those superclass methods do not report that.
The very helpful answer by #insane-36 showed a way to do it when collectionView.bounds == collectionView.collectionViewContentSize.
But if you wish to support the case where collectionView.bounds < collectionViewcontentSize, then I believe you need to re-map the rects exactly to support scrolling properly. If you wish to support the case where collectionView.bounds > collectionViewContentSize, then you need to override collectionViewContentSize to ensure the content rect is positioned at the bottom of the collectionView (since otherwise it will be positioned at the top, due to the top-to-bottom default behavior of UIScrollView).
So the full solution is a bit more involved, and I ended up developing it here: https://github.com/algal/ALGReversedFlowLayout.
You could basically implement it with a simple logic, however this seems to be some how odd. If the collectionview contentsize is same as that of the collectionview bounds or if all the cells are visible then you could implement this with simple flowLayout as this,
#implementation SimpleFlowLayout
- (UICollectionViewLayoutAttributes*)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{
UICollectionViewLayoutAttributes *attribute = [super layoutAttributesForItemAtIndexPath:indexPath];
[self modifyLayoutAttribute:attribute];
return attribute;
}
- (NSArray*)layoutAttributesForElementsInRect:(CGRect)rect{
NSArray *attributes = [super layoutAttributesForElementsInRect:rect];
for(UICollectionViewLayoutAttributes *attribute in attributes){
[self modifyLayoutAttribute:attribute];
}
return attributes;
}
- (void)modifyLayoutAttribute:(UICollectionViewLayoutAttributes*)attribute{
CGSize contentSize = self.collectionViewContentSize;
CGRect frame = attribute.frame;
frame.origin.x = contentSize.width - attribute.frame.origin.x - attribute.frame.size.width;
frame.origin.y = contentSize.height - attribute.frame.origin.y - attribute.frame.size.height;
attribute.frame = frame;
}
#end
And so the figure looks like this,
But, if you use more rows, more than the that can be seen on the screen at the same time, then there seems to be some problem with reusing. Since the UICollectionView datasource method, collectionView:cellForItemAtIndexPath: works linearly and asks for the indexPath as the user scrolls, the cell are asked in the usual increasing indexPath pattern such as 1 --- 100 though we would want it to reverse this pattern. While scrolling we would need the collectionView to ask us for the items in decreasing order since our 100 item resides at top and 1 item at bottom. So, I dont have any particular idea about how this could be accomplished.
UICollectionView with a reversed flow layout.
import Foundation
import UIKit
class InvertedFlowLayout: UICollectionViewFlowLayout {
override func prepare() {
super.prepare()
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
guard super.layoutAttributesForElements(in: rect) != nil else { return nil }
var attributesArrayNew = [UICollectionViewLayoutAttributes]()
if let collectionView = self.collectionView {
for section in 0 ..< collectionView.numberOfSections {
for item in 0 ..< collectionView.numberOfItems(inSection: section) {
let indexPathCurrent = IndexPath(item: item, section: section)
if let attributeCell = layoutAttributesForItem(at: indexPathCurrent) {
if attributeCell.frame.intersects(rect) {
attributesArrayNew.append(attributeCell)
}
}
}
}
for section in 0 ..< collectionView.numberOfSections {
let indexPathCurrent = IndexPath(item: 0, section: section)
if let attributeKind = layoutAttributesForSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, at: indexPathCurrent) {
attributesArrayNew.append(attributeKind)
}
}
}
return attributesArrayNew
}
override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
let attributeKind = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: elementKind, with: indexPath)
if let collectionView = self.collectionView {
var fullHeight: CGFloat = 0.0
for section in 0 ..< indexPath.section + 1 {
for item in 0 ..< collectionView.numberOfItems(inSection: section) {
let indexPathCurrent = IndexPath(item: item, section: section)
fullHeight += cellHeight(indexPathCurrent) + minimumLineSpacing
}
}
attributeKind.frame = CGRect(x: 0, y: collectionViewContentSize.height - fullHeight - CGFloat(indexPath.section + 1) * headerHeight(indexPath.section) - sectionInset.bottom + minimumLineSpacing/2, width: collectionViewContentSize.width, height: headerHeight(indexPath.section))
}
return attributeKind
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
let attributeCell = UICollectionViewLayoutAttributes(forCellWith: indexPath)
if let collectionView = self.collectionView {
var fullHeight: CGFloat = 0.0
for section in 0 ..< indexPath.section + 1 {
for item in 0 ..< collectionView.numberOfItems(inSection: section) {
let indexPathCurrent = IndexPath(item: item, section: section)
fullHeight += cellHeight(indexPathCurrent) + minimumLineSpacing
if section == indexPath.section && item == indexPath.item {
break
}
}
}
attributeCell.frame = CGRect(x: 0, y: collectionViewContentSize.height - fullHeight + minimumLineSpacing - CGFloat(indexPath.section) * headerHeight(indexPath.section) - sectionInset.bottom, width: collectionViewContentSize.width, height: cellHeight(indexPath) )
}
return attributeCell
}
override var collectionViewContentSize: CGSize {
get {
var height: CGFloat = 0.0
var bounds = CGRect.zero
if let collectionView = self.collectionView {
for section in 0 ..< collectionView.numberOfSections {
for item in 0 ..< collectionView.numberOfItems(inSection: section) {
let indexPathCurrent = IndexPath(item: item, section: section)
height += cellHeight(indexPathCurrent) + minimumLineSpacing
}
}
height += sectionInset.bottom + CGFloat(collectionView.numberOfSections) * headerHeight(0)
bounds = collectionView.bounds
}
return CGSize(width: bounds.width, height: max(height, bounds.height))
}
}
override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
if let oldBounds = self.collectionView?.bounds,
oldBounds.width != newBounds.width || oldBounds.height != newBounds.height {
return true
}
return false
}
func cellHeight(_ indexPath: IndexPath) -> CGFloat {
if let collectionView = self.collectionView, let delegateFlowLayout = collectionView.delegate as? UICollectionViewDelegateFlowLayout {
let size = delegateFlowLayout.collectionView!(collectionView, layout: self, sizeForItemAt: indexPath)
return size.height
}
return 0
}
func headerHeight(_ section: Int) -> CGFloat {
if let collectionView = self.collectionView, let delegateFlowLayout = collectionView.delegate as? UICollectionViewDelegateFlowLayout {
let size = delegateFlowLayout.collectionView!(collectionView, layout: self, referenceSizeForHeaderInSection: section)
return size.height
}
return 0
}
}