How to set UICollectionView bottom padding and scrolling size - ios

Question

Hello I have working uicollectionview custom layout and i have issuesfor bottom padding and scrolling sizes. Under below picture you can see;
Also top side first cell always stays on top when scrolling ( Left side cell must be always stay right now no problem there , but top side cell must be scroll when scrolling )
I try to set in viewDidLoad under below codes but dont work
self.automaticallyAdjustsScrollViewInsets = false
self.collectionView.contentInset = UIEdgeInsetsMake(20, 20, 120, 100);
My custom collectionview layout file
import UIKit
public var CELL_HEIGHT = CGFloat(22)
protocol CustomCollectionViewDelegateLayout: NSObjectProtocol {
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, widthForItemAtIndexPath indexPath: NSIndexPath) -> CGFloat
}
class CustomCollectionViewLayout: UICollectionViewLayout {
// Used for calculating each cells CGRect on screen.
// CGRect will define the Origin and Size of the cell.
let STATUS_BAR = UIApplication.sharedApplication().statusBarFrame.height
// Dictionary to hold the UICollectionViewLayoutAttributes for
// each cell. The layout attribtues will define the cell's size
// and position (x, y, and z index). I have found this process
// to be one of the heavier parts of the layout. I recommend
// holding onto this data after it has been calculated in either
// a dictionary or data store of some kind for a smooth performance.
var cellAttrsDictionary = Dictionary<NSIndexPath, UICollectionViewLayoutAttributes>()
// Defines the size of the area the user can move around in
// within the collection view.
var contentSize = CGSize.zero
// Used to determine if a data source update has occured.
// Note: The data source would be responsible for updating
// this value if an update was performed.
var dataSourceDidUpdate = true
weak var delegate: CustomCollectionViewDelegateLayout?
override func collectionViewContentSize() -> CGSize {
return self.contentSize
}
override func prepareLayout() {
// Only update header cells.
if !dataSourceDidUpdate {
// Determine current content offsets.
let xOffset = collectionView!.contentOffset.x
let yOffset = collectionView!.contentOffset.y
if collectionView?.numberOfSections() > 0 {
for section in 0...collectionView!.numberOfSections()-1 {
// Confirm the section has items.
if collectionView?.numberOfItemsInSection(section) > 0 {
// Update all items in the first row.
if section == 0 {
for item in 0...collectionView!.numberOfItemsInSection(section)-1 {
// Build indexPath to get attributes from dictionary.
let indexPath = NSIndexPath(forItem: item, inSection: section)
// Update y-position to follow user.
if let attrs = cellAttrsDictionary[indexPath] {
var frame = attrs.frame
// Also update x-position for corner cell.
if item == 0 {
frame.origin.x = xOffset
}
frame.origin.y = yOffset
attrs.frame = frame
}
}
// For all other sections, we only need to update
// the x-position for the fist item.
} else {
// Build indexPath to get attributes from dictionary.
let indexPath = NSIndexPath(forItem: 0, inSection: section)
// Update y-position to follow user.
if let attrs = cellAttrsDictionary[indexPath] {
var frame = attrs.frame
frame.origin.x = xOffset
attrs.frame = frame
}
}
}
}
}
// Do not run attribute generation code
// unless data source has been updated.
return
}
// Acknowledge data source change, and disable for next time.
dataSourceDidUpdate = false
var maxWidthInASection = CGFloat(0)
// Cycle through each section of the data source.
if collectionView?.numberOfSections() > 0 {
for section in 0...collectionView!.numberOfSections()-1 {
// Cycle through each item in the section.
if collectionView?.numberOfItemsInSection(section) > 0 {
var prevCellAttributes: UICollectionViewLayoutAttributes?
for item in 0...collectionView!.numberOfItemsInSection(section)-1 {
let cellIndex = NSIndexPath(forItem: item, inSection: section)
guard let width = delegate?.collectionView(collectionView!, layout: self, widthForItemAtIndexPath: cellIndex) else {
print("Please comform to CustomCollectionViewDelegateLayout protocol")
return
}
// Build the UICollectionVieLayoutAttributes for the cell.
var xPos = CGFloat(0)
let yPos = CGFloat(section) * CELL_HEIGHT
if let prevCellAttributes = prevCellAttributes {
xPos = CGRectGetMaxX(prevCellAttributes.frame)
}
let cellAttributes = UICollectionViewLayoutAttributes(forCellWithIndexPath: cellIndex)
cellAttributes.frame = CGRect(x: xPos, y: yPos, width: width, height: CELL_HEIGHT)
// Determine zIndex based on cell type.
if section == 0 && item == 0 {
cellAttributes.zIndex = 4
} else if section == 0 {
cellAttributes.zIndex = 3
} else if item == 0 {
cellAttributes.zIndex = 2
} else {
cellAttributes.zIndex = 1
}
// Save the attributes.
cellAttrsDictionary[cellIndex] = cellAttributes
prevCellAttributes = cellAttributes
let maxX = CGRectGetMaxX(cellAttributes.frame)
if maxWidthInASection < maxX {
maxWidthInASection = maxX
}
}
}
}
}
// Update content size.
let contentWidth = maxWidthInASection
let contentHeight = Double(collectionView!.numberOfSections())
self.contentSize = CGSize(width: Double(contentWidth), height: contentHeight)
self.contentSize.height = CGFloat(Double(collectionView!.numberOfSections()))
}
override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
// Create an array to hold all elements found in our current view.
var attributesInRect = [UICollectionViewLayoutAttributes]()
// Check each element to see if it should be returned.
for cellAttributes in cellAttrsDictionary.values.elements {
if CGRectIntersectsRect(rect, cellAttributes.frame) {
attributesInRect.append(cellAttributes)
}
}
// Return list of elements.
return attributesInRect
}
override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes? {
return cellAttrsDictionary[indexPath]!
}
override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
return true
}
}
I try change collecionview properties in storyboard but doesnt works also i attached current collectionview object properties picture under below
Also i selected zoom 4 but zoom feature doesnt work ? why ? it must be work also zoom feature.

Answer 1

I know this is too late to answer, but this could be useful to other users.
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
collectionView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 50, right: 0)
}

Answer 2

This what worked for me:
messagesCollectionView.contentInset.top = 100
messagesCollectionView.contentInset.bottom = 80

Answer 3

This can be also done on IB under section insets...