I have to Collection View in my view Controller. One is Showing the image and the other is showing the ticket details. Here is the sample image.
But I can't set the proper constraint. This is what I Do with code.
let numberOfCells = 9
let kCellHeight : CGFloat = 104
let kLineSpacing : CGFloat = 2
let kInset : CGFloat = 10
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if collectionView == clnView {
return CGSize.init(width: width, height: height)
}else {
return CGSize(width: (UIScreen.main.bounds.width - 2*kInset - kLineSpacing), height: kCellHeight)
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
var size = CGFloat()
if collectionView == clnView {
size = kLineSpacing
}
return size
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
var Insect = UIEdgeInsets()
if collectionView == clnView {
Insect = UIEdgeInsets(top: kInset, left: kInset, bottom: kInset, right: kInset)
}
return Insect
}
But It's not showing properly. Look
iphone 5s
iPhone XR
Please Explain the Correct way. Thanks
Your code simply defines how items are laid out inside the collection view.
Constraints should tell you where in your parent view collection view is placed, and how wide + high.
You must learn autolayout and do it step by step in your storyboard or xib for the view. With proper Y constraint, it should work as expected. If you are putting collectionview + other things inside scrollview, follow this answer.
Related
I did create a custom calendar based on UICollectionView.
One UICollectionViewCell - one date in the calendar. I want to delete spacing between cells.
CollectionView layout settings -
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: (collectionView.frame.width / 7), height: collectionView.frame.width / 7)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0.0
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0.0
}
In different screen sizes, unless iPhone X, we will see the spacing between cells.
How to fix it?
You probably have a rounding error. You are saying
collectionView.frame.width / 7
An iPhone 11 is 414 points wide. 414 / 7 is 59.14285714. There is no way to portray a fractional point on the screen, so now what? We round down, and now there is an extra pixel space between cells.
This is occurring because of the rounding-off of decimal places when your providing collectionView.frame.width / 7 just as matt has said in his answer. Seems you are trying to avoid this because you don't want users to see that bit of gap between the cells. Mostly you would only see this on a simulator an not on a real device due to the pixel density. You can overcome this fault either by replacing the UICollectionViewFlowLayout with a UICollectionViewCompositionalLayout which is available only from iOS 12. A simple fix would be to create a custom background view for the cell that extends the UICollectionViewCell by just 1 pixel. Here is an example of how I tried to achieve this:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
cell.backgroundColor = .purple
let view = UIView()
view.backgroundColor = .brown
cell.addSubview(view) // Comment this line and you can see the gap
view.frame = cell.bounds
view.frame.size = CGSize(width: view.frame.size.width + 1, height: view.frame.size.height + 1)
return cell
}
This was a nice little hack I found a while back. Hope this helps you too.
I found a solution -
1. Delete from storyboard leading and trailing constraints from calendar view.
2. Set center horizontally constraint
3. Set width constraint to calendar view.
4. Create #IBOutlet calendarWidthConstraint
5. In viewDidLoad -
let layout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
let width = self.view.frame.width
let cellSize = CGFloat(width / 7).rounded()
let newWidth = cellSize * 7
layout.itemSize = CGSize(width: cellSize, height: cellSize)
calendarWidth.constant = newWidth
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
collectionView.collectionViewLayout = layout
When I swipe through my collectionView cells they are cut off the page for some reason even tho the first cell is fine. When I get the the last cell then swipe again it bounces and then the last cell displays correctly. see video
In the video the blue is an imageView in the cell. Green, orange and purple are collectionView cells and white is the collectionView background.
first give the value of collection cell spacing 0.
add the code for collection-layout.
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath:
IndexPath) -> CGSize {
let height = UIScreen.main.bounds.height
let width = UIScreen.main.bounds.width
return CGSize(width: width, height: height) }
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout: UICollectionViewLayout, insetForSectionAt
Selection: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0) }
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout:
UICollectionViewLayout,minimumInteritemSpacingForSectionAt selection:
Int) -> CGFloat{
return 0 }
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout:
UICollectionViewLayout,minimumLineSpacingForSectionAt selection: Int)
-> CGFloat{
return 0 }
if still it doesn't work then send your code... :)
I would like to have the first section's cells be the full width of the collection view and the second section be half of the width. On startup, the cells don't respect the given width although the height seems to be respected. After a couple of seconds, the collection view is reloaded and most of the time it sets the cells to the correct sizes. When the phone's orientation changes to landscape, the cells are drawn in the incorrect sizes again.
I've tried using UICollectionViewDelegateFlowLayout and the sizeForItemAt delegate function to set the cell sizes but they don't follow the given sizes even if the function is being called.
Currently, I am setting section insets and then calculating the remaining available width for the cells in the collection view's bounds, afterward I divide the width by the number of cells per row.
class HomeCollectionViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
let sectionInsets = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
override func viewDidLoad() {
super.viewDidLoad()
self.collectionView?.contentInsetAdjustmentBehavior = .always
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.width, height: 44)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return self.sectionInsets
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return self.sectionInsets.left
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
var numberOfItemsPerRow: CGFloat = 1
var height: CGFloat = 0
switch indexPath.section {
case 0:
numberOfItemsPerRow = 1
height = 97
case 1:
numberOfItemsPerRow = 2
height = 126
default:
break
}
let padding = self.sectionInsets.left * (numberOfItemsPerRow + 1)
let availableWidth = collectionView.bounds.size.width - padding
let width = availableWidth / numberOfItemsPerRow
return CGSize(width: width, height: height)
}
}
This results in the cells to be sized incorrectly as in the following image. Incorrect Example Image
The only time they are sized correctly is after the collection view is reloaded. Correct Example Image
Also, when the phone turns to landscape it displays it incorrectly. Incorrect Landscape Example Image
To conclude my issue, the first section's cells should always take 100% of the available width. If possible it would be very nice if they would have an automatic height. I've tried using UICollectionViewFlowLayout.automaticSize.height but I don't think that would work. For the second section, it needs to always take 50% of the available width.
If you're using Storyboard to create the CollectionView.
I thought I had to invalidateLayout(). It turns out there's a weird bug with iOS 13.
you have to create your own UICollectionViewFlowLayout. Call something like this in your viewDidLoad()
collectionView.collectionViewLayout = {
let flowLayout = UICollectionViewFlowLayout()
flowLayout.scrollDirection = .horizontal
return flowLayout
}()
You must invalidate layout on viewDidLayoutSubviews to re-calculate sizes for cells.
I have attached code snippet. Try this one
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
collectionView.collectionViewLayout.invalidateLayout()
}
I am displaying several images in a collection view. They are all the same orientation (landscape) except for one, which is portrait (see image below):
I am trying to make the portrait image more centered, so that everything is evenly spaced. Any ideas on how to do this?
PhotoGalleryViewController.swift:
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return images.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! PhotoGalleryCell
let image = UIImage(named: images[indexPath.row])
cell.imageView.image = image
cell.captionLabel.text = captions[indexPath.row]
return cell
}
func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
var size = CGSize()
if (indexPath.row == 3)
{
size = CGSize(width: 450, height: 600)
}
else {
size = CGSize(width: 940, height: 600)
}
return size
}
My suggestion would be not altering the cell size based on the fact that a portrait image will be in item 3.
Instead update the layout of your cell so that whatever image it gets assigned to it's image view, it will centre the image in itself and centralise the label underneath the image.
In ViewDidLoad method put this code :
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 20, bottom: 0, right: 20)
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
collectionview.collectionViewLayout = layout
Also add this into cellForRow Methods:
cell.imageview.contentmode = .aspectfit
Hope it helps to resolve your issue.
Hi I'm trying to resize the cell via the auto layout.
I want display the cell by the 3 by 3.
First Cell's margin left=0
Last Cell's margin right=0
And all of the cell's space has 1pt. Like an instagram.
Should I set to Cell's Size? I want set constraint via the Autolayout.
I also trying to set cell's size using the code.
Here is my code:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
return CGSizeMake(123, 123);
}
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAtIndex section: Int) -> CGFloat {
return 1;
}
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAtIndex section: Int) -> CGFloat {
return 1;
}
But..I think it is not exactly calculate the cell's size.
How do I set cell's size depending on the screen's size?
I have to set space the 1pt between cell's.
Is there anyway to set only using the storyboard?
If not, How do I set by the code?
Thank you.
I don't believe you can set the size by only using the Storyboard because you can't set constraints to recurring items like collection view cells that are created on the fly at runtime.
You can easily compute the size from the information you are given. In collectionView(_:layout:sizeForItemAt:) you can access the bounds of the collectionView to compute the desired size of your cell:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
// Compute the dimension of a cell for an NxN layout with space S between
// cells. Take the collection view's width, subtract (N-1)*S points for
// the spaces between the cells, and then divide by N to find the final
// dimension for the cell's width and height.
let cellsAcross: CGFloat = 3
let spaceBetweenCells: CGFloat = 1
let dim = (collectionView.bounds.width - (cellsAcross - 1) * spaceBetweenCells) / cellsAcross
return CGSize(width: dim, height: dim)
}
Make sure your class adopts the protocol UICollectionViewDelegateFlowLayout.
This then works for iPhones and iPads of all sizes.
Great answer by vacawama but I had 2 issues. I wanted the spacing that I defined in storyboard to automatically be used.
And secondly, I could not get this function to invoke and no one mentioned how? In order to invoke the collectionView's sizeForItemAt you need to extend UICollectionViewDelegateFlowLayout instead of extending UICollectionViewDelegate. I hope this saves someone else some time.
extension MyViewController: UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let cellsAcross: CGFloat = 3
var widthRemainingForCellContent = collectionView.bounds.width
if let flowLayout = collectionViewLayout as? UICollectionViewFlowLayout {
let borderSize: CGFloat = flowLayout.sectionInset.left + flowLayout.sectionInset.right
widthRemainingForCellContent -= borderSize + ((cellsAcross - 1) * flowLayout.minimumInteritemSpacing)
}
let cellWidth = widthRemainingForCellContent / cellsAcross
return CGSize(width: cellWidth, height: cellWidth)
}
}
I set it up using CollectionView's delegate methods. This will give you a 2xN setup but you can easily make it a 3xN instead. Here's a screenshot and you can refer to my project on GitHub...
https://github.com/WadeSellers/GoInstaPro
Swift 3 version code based on vacawama answer:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let cellsAcross: CGFloat = 3
let spaceBetweenCells: CGFloat = 1
let dim = (collectionView.bounds.width - (cellsAcross - 1) * spaceBetweenCells) / cellsAcross
return CGSize(width: dim, height: dim)
}
Here is another solution but It only works on iPhone6.
I will trying to update for iphone5/6plus
Special thanks to #vacawama!
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
// Compute the dimension of a cell for an NxN layout with space S between
// cells. Take the collection view's width, subtract (N-1)*S points for
// the spaces between the cells, and then divide by N to find the final
// dimension for the cell's width and height.
let cellsAcross: CGFloat = 3
let spaceBetweenCells: CGFloat = 1
let dim = (collectionView.bounds.width - (cellsAcross - 1) * spaceBetweenCells) / cellsAcross
print(indexPath.row)
var width = dim
//last cell's width
if( (indexPath.row + 1) % 3 == 0){
width = 124
}else {
width = 124.5
}
print(width)
return CGSize(width: width , height: dim)
}
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAtIndex section: Int) -> CGFloat {
return 1;
}
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAtIndex section: Int) -> CGFloat {
return 1;
}