I have a UIViewController (named Friends) with a tableview and I want to display views above the Controller's view when the user is offline. This is how I create my views
class func showOffline(host: UIViewController) {
// showOffline image
var disconnectedImage = UIImage(named: "offlineIconGrey")
disconnectedImage = disconnectedImage?.imageWithRenderingMode(.AlwaysOriginal)
let imageView = UIImageView(image: disconnectedImage)
imageView.center = CGPoint(x: host.view.center.x,
y: host.view.center.y - imageView.frame.height/2)
// showOffline Label
let Label = UILabel(frame: CGRect(x: 0, y: 0, width: 0, height: 0))
let labelText = "You appear to be offline \n Please connect to the internet"
Label.center = CGPoint(x: host.view.center.x,
y: imageView.center.y + 3*imageView.frame.height/4)
Label.numberOfLines = 0
Label.text = labelText
Label.textAlignment = .Center
Label.font = UIFont(name: (Label.font?.fontName)!, size: 14.0)
Label.sizeToFit()
Label.textColor = UIColor.whiteColor()
Label.lineBreakMode = .ByCharWrapping
Label.frame.offsetInPlace(dx: -Label.frame.size.width/2, dy: 0)
host.view.insertSubview(imageView, aboveSubview: host.view)
host.view.insertSubview(Label, aboveSubview: host.view)
}
Now it is my understanding, that the host view (host.view) should be the topmost view as that is shown on my storyboard; however, when I call my showOffline function like so
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
if !Reachability.isConnected() {
state = .Offline
} else {
state = .Default
}
}
where offline state calls,
General.showOffline(self)
like so
var state: State = .Default {
didSet {
switch (state) {
case .Default:
print("ViewMode = Default")
//query = ParseHelper.allUsers(updateList)
case .Search:
let searchText = searchBar?.text ?? ""
print(searchText)
//query = ParseHelper.searchUsers(searchText, completionBlock:updateList)
case .Offline:
General.showOffline(self)
searchBar.userInteractionEnabled = false
query = nil
users = [PFUser]() ?? []
print("ViewMode = Offline")
}
}
}
the views do not appear as the topmost views unless I am returning to the view controller (Friends) from a show segue. Otherwise, navigating to that view controller does not show the labels when it should? Am I missing something? I have tried to fix the problem by placing the views above the tableview but in that case the math for centering the views is off, probably because I am not loading any cells and I have a footer view as a UIView. I also tried adding the views to the tableview's footer view, but that didn't work either. What I DON'T want is to add the views to the navigation controller's view as I do not want that behavior, though I will do that if I have no other option.
This is what I want
Can someone please tell me what I am doing wrong or refer me to information that may help me fix my problem? Thanks!
host.view.insertSubview(imageView, aboveSubview: host.view)
This cannot work. You add a subview to host.view. The "aboveSubview" must be a subview of host.view. There are other methods for g
adding a subview.
When you call insertSubview:aboveSubview:, the view you give as second parameter must be a subview of the view you're inserting in. Here, it's the same view, so obviously it won't work.
Unless there are other views that should remain above the ones you're inserting, the easiest way is to just use addSubview:, which will make the new view topmost among the child of the target view.
Related
Problem:
I am trying to create my own custom search field with a desired growing animation (if you click on it), and a shrinking animation when the user taps out.
The animation behaves weirdly since it moves out of the right screen bounds when shrinking, even though the text field/search bar's right anchor is not modified.
Like so:
Notice how the right side of the search bar briefly moves outside of the visible screen bounds during the animation.
Expected behavior:
The search bar should smoothly grow/shrink without moving the right edge position of the text field, i.e. have the right anchor stay pinned.
What you see in above gif is built using the following code (by subclassing a UITextField):
public class MySearchBar: UITextField {
private var preAnimationWidth: NSLayoutConstraint?
private var postAnimationWidth: NSLayoutConstraint?
public override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = Theme.GRAY800
self.borderStyle = .roundedRect
self.layer.masksToBounds = true
self.clipsToBounds = true
self.autocorrectionType = .no
self.font = FontFamily.ProximaNova.regular.font(size: 16)
self.textColor = .white
self.attributedPlaceholder = NSAttributedString(string: "Search", attributes: [.foregroundColor : Theme.GRAY400, .font: FontFamily.ProximaNova.regular.font(size: 16)])
// some further appearance configurations
}
public func setupGrowAnimation(initialWidth: NSLayoutConstraint, grownWidth: NSLayoutConstraint, height: CGFloat) {
preAnimationWidth = initialWidth
postAnimationWidth = grownWidth
self.layer.borderWidth = 0
self.layer.cornerRadius = height / 2
}
// growButton is called when the textfield becomes active, i.e. the user taps on it.
public func growButton() {
guard let preAnimationWidth = preAnimationWidth, let postAnimationWidth = postAnimationWidth else { return }
UIView.animate(withDuration: 0.2) {
preAnimationWidth.isActive = false
postAnimationWidth.isActive = true
self.layer.borderColor = Theme.GRAY600.cgColor
self.layer.borderWidth = 2
self.layer.cornerRadius = 8
self.layoutIfNeeded()
}
}
// shrinkButton is called whenever the textfield resigns its first responder state, i.e. the user clicks out of it.
public func shrinkButton() {
guard let preAnimationWidth = preAnimationWidth, let postAnimationWidth = postAnimationWidth else { return }
UIView.animate(withDuration: 0.2) {
postAnimationWidth.isActive = false
preAnimationWidth.isActive = true
self.layer.borderWidth = 0
self.layer.borderColor = .none
self.layer.cornerRadius = self.frame.height / 2
self.layoutIfNeeded()
}
}
}
And this is how the search bar is initialized in my viewDidLoad:
override func viewDidLoad() {
let containerView = UIView()
let searchBar = MySearchBar()
searchBar.addTarget(self, action: #selector(searchBarChangedEntry(_:)), for: .editingChanged)
searchBar.addTarget(self, action: #selector(searchBarEndedEditing(_:)), for: .editingDidEnd)
searchBar.translatesAutoresizingMaskIntoConstraints = false
let initialWidth = searchBar.widthAnchor.constraint(equalToConstant: 100)
let expandedWidth = searchBar.widthAnchor.constraint(equalTo: containerView.widthAnchor, constant: -32)
searchBar.setupGrowAnimation(initialWidth: initialWidth, grownWidth: expandedWidth, height: 44)
containerView.addSubview(searchBar)
stackView.insertArrangedSubview(containerView, at: 0)
NSLayoutConstraint.activate([
containerView.heightAnchor.constraint(equalToConstant: 44),
containerView.widthAnchor.constraint(equalTo: self.stackView.widthAnchor),
searchBar.heightAnchor.constraint(equalTo: containerView.heightAnchor),
initialWidth,
searchBar.rightAnchor.constraint(equalTo: containerView.rightAnchor, constant: -16)
])
self.stackView.setCustomSpacing(12, after: containerView)
}
The search bar is part of a container view which, in turn, is the first (top) arranged subview of a stack view covering the entire screen's safeAreaLayout rectangle
What I already tried:
I have to perform the animation using constraints, and I've tried to animate it without using the width anchor (e.g. by animating the leftAnchor's constant). Nothing worked so far.
Upon googling, I couldn't really find anything helpful that would help me find a solution to this problem, which is why I am trying my luck here.
I do have to admit that I am not proficient with animations of iOS at all - so please bear with me if this is a simple mistake to fix.
So, why does the search bar behave that way? And how can I fix this?
A little tough to say, because the code you posted is missing a lot of information (for example, you don't show the creation of the stackView, nor where its being added to the view hierarchy).
However, you might fix your issue with this simple change...
In both your growButton() and shrinkButton() funcs, change this line in the animation block:
self.layoutIfNeeded()
to this:
self.superview?.layoutIfNeeded()
Edit - a little explanation...
To animate constraint changes, we want to call .layoutIfNeeded() on the top-most view that will be affected.
When calling:
UIView.animate(withDuration: 0.5) {
self.someView.layoutIfNeeded()
}
we're telling auto-layout to calculate the changes and then generate and run an animation... but only for someView and its subviews.
If our action is going to affect someView.superview - or, for example, the constraint change is going to move/size a sibling of someView or a sibling of someView.superview, we haven't told auto-layout to include those views in its layout calculations.
I expect there are specific implementations / layout hierarchies where one would want to specifically exclude some views from the layout / animation... but...
Personally, I do this:
UIView.animate(withDuration: 0.5) {
self.view.layoutIfNeeded()
}
because the constraint I want to animate might be on a subview deep in the view hierarchy - and could have 4 or 5 or 6 etc superviews - all of which could be affected by the change.
Please refer to this Answer.
I am trying to do the same thing, however I want to do this in a Tab Bar App where the Now Playing bar is above the Tab Bar in all the scenes of the app.
Update:
I want to have a view at the bottom of the screen (above the tab bar) and under the content views of the different tabs (not above them). In addition, I want to have the ability to remove this view at a certain point making the main view take the whole screen.
I can do this using the mentioned Answer by changing the constraints of the nowPlaying view programmatically.
Using UITabBarViewController subclass it is possible:
Ex:
class DashBoardViewController: UITabBarController {
let nowPlayingBar:UIView = {
let view = UIView(frame: .zero)
view.backgroundColor = .blue
return view
}()
override func viewDidLoad() {
super.viewDidLoad()
initView()
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
nowPlayingBar.frame = tabBar.frame
}
override func viewDidAppear(_ animated: Bool) {
var newSafeArea = UIEdgeInsets()
// Adjust the safe area to accommodate
// the height of the bottom views.
newSafeArea.bottom += nowPlayingBar.bounds.size.height
// Adjust the safe area insets of the
// embedded child view controller.
self.childViewControllers.forEach({$0.additionalSafeAreaInsets = newSafeArea})
}
private func initView() {
nowPlayingBar.frame = tabBar.frame
view.addSubview(nowPlayingBar)
}
}
You'll add your view/container to your app window, you'd do something like
guard let window = (UIApplication.shared.delegate as? AppDelegate)?.window
else { return } // check if there's a window
let containerHeight: CGFloat = 50 // height for the view where you wish to add the music player
let containerFrame = CGRect(x:0, y: window.frame.maxY - (tabBar.frame.height + containerHeight), width: window.frame.width, height: containerHeight)
// most important part here is the y axis in some sense, you will add the height of the tabBar and the container, then subtract it from window.frame.maxY
let container = UIView(frame: containerFrame)
// now you have the container do whatever you want with it
window.addSubView(container) // finally add the container to window as a subview
Situation: I've got a UITableViewController loading some data asynchronously from a service. During this time I would like to place a full screen (except navigation bar) view over the table view showing my custom indicator and text.
Problem: The problem I'm facing is that when my custom view (it has a red background) is placed over the UITableView the lines of the table view are shown trough my custom view (see image below).
What I tried:
I tried to use insertBelow and above, didn't work. I also tried to do: tableview.Hidden = true, but this also hides the custom view for some reason as seen on image 2.
Image1: For some reason I can see the lines threw my view.
Image 2: Tableview + custom view gone when hidden = true used.
My code:
public override void ViewDidLoad ()
{
base.ViewDidLoad ();
UIView view = new UIView (new RectangleF (0, 0, this.TableView.Frame.Width, this.TableView.Frame.Height));
view.BackgroundColor = UIColor.Red;
this.TableView.AddSubview (view);
TableView.Source = new SessionTableViewSource ();
}
You can use self.navigationController.view as view for adding subview.
The issue is that the View of a UITableViewController is a UITableView, so you cannot add subviews to the controller on top of the table.
I'd recommend switching from a UITableViewController to a simple UIViewController that contains a UITableView. This way the controller main view is a plain UIView that contains a table, and you can add subviews to the main UIView and they will be placed on top of the table view.
You can try to add the view to the window instead of nesting it in the table view like this:
UIWindow* mainWindow = [[UIApplication sharedApplication] keyWindow];
[mainWindow addSubview: overlayview];
UIWindow* window = [[UIApplication sharedApplication].delegate.window;
[window addSubview: your-overlayview];
Swift / Storyboard Solution
Note: The code below assumes one has a custom view (ratingView in my case) that is to be presented over a UITableView.
I've read many answers to this and similar questions on SO. The other answers from these sources worked to varying degrees for me (e.g.,view loaded but not shown or not accessible,...). I am using Swift 2.0+ and I am sharing the complete solution for doing this using a UITableViewController.
Create an outlet to the Navigation Bar and the view, which you want to bring over the tableview.
//MARK:Outlets
#IBOutlet weak var navBar:UINavigationBar!
#IBOutlet var ratingView: MNGStarRating!
In my case I also wanted to animate the view over the tableview so I used a class variable to hold a reference to the inflection point and a point above the scene (off-screen).
var centerYInflection:NSLayoutConstraint!
var aPointAboveScene = -(max(UIScreen.mainScreen().bounds.width,UIScreen.mainScreen().bounds.height) * 2.0)
Then in viewDidLoad I called a function (configureRatingViewAutoLayout) which configures and adds the constraints for the new view to be animated over the tableview.
func configureRatingViewAutoLayout() {
//REQUIRED
self.navBar.superview?.addSubview(self.ratingView)
var newConstraints:[NSLayoutConstraint] = []
newConstraints.append(self.ratingView.leadingAnchor.constraintEqualToAnchor(self.view.leadingAnchor,constant: 10))
newConstraints.append(self.ratingView.trailingAnchor.constraintEqualToAnchor(self.view.trailingAnchor,constant: 10))
newConstraints.append(self.ratingView.centerXAnchor.constraintEqualToAnchor(self.view.centerXAnchor))
//hides the rating view above the scene
self.centerYInflection = self.ratingView.centerYAnchor.constraintEqualToAnchor(self.view.centerYAnchor, constant: self.aPointAboveScene)
//the priority must be set below 1000 if you intend to change it after it has been added to a view
self.centerYInflection.priority = 750
newConstraints.append(self.centerYInflection)
//constraints must be added to the container view of the two items
self.ratingView.superview?.addConstraints(newConstraints)
}
Nota Bene - On a UITableViewController; the self.view is the
self.tableView. They point to the same thing so I guess one could also
use the self.tableView reference above.
Sometime later... In response to a UIControl event I call this method.
#IBAction func toggleRatingView (sender:AnyObject?){
//REQUIRED
self.ratingView.superview?.layoutIfNeeded()
UIView.animateWithDuration(1.0, delay: 0.0, usingSpringWithDamping: 0.37, initialSpringVelocity: 0.99, options: [.CurveEaseOut], animations: { () -> Void in
if CGRectContainsRect(self.view.frame, self.ratingView.frame) {
//in frame ~ animate away
//I play a sound to alert the user something is happening
self.centerYInflection.constant = self.aPointAboveScene
self.centerYInflection.priority = UILayoutPriority(950)
//I disable portions of the UI
self.disableUIElements(nil)
} else {
//out of frame ~ animate in
//I play a different sound here
self.centerYInflection.constant = 0
self.centerYInflection.priority = UILayoutPriority(950)
//I enable the UI fully
self.enableUIElements(nil)
}
//REQUIRED
self.ratingView.superview?.setNeedsLayout()
self.ratingView.superview?.layoutIfNeeded()
}) { (success) -> Void in
//do something else
}
}
These helper methods can be configured to control access to elements in your scene during the presentation of the view.
func disableUIElements(sender:AnyObject?) {
//UI
}
func enableUIElements(sender:AnyObject?) {
//UI
}
Caveats
My view is a custom view in the Storyboard (sitting outside of the
tableview but connected to the TableView Controller). The view has a
required user runtime attribute defined layer.zPosition with a Number value set to 2 (this ensures that it presents in front of the
UITableView).
One could also try playing around with bringSubviewToFront:
and sendSubviewToBack: methods if you don't want to set the zPosition
(I think zPosition is simpler to use)
Try this to hook a button at bottom of the UITableViewController
declare button as a variable:
var submitButton: UIButton!
and in viewDidLoad:
submitButton = UIButton(frame: CGRect(x: 5, y: UIScreen.main.bounds.size.height - 50, width: UIScreen.main.bounds.size.width - 10, height: 50))
submitButton.backgroundColor = UIColor.init(red: 180/255, green: 40/255, blue: 56/255, alpha: 1.0)
submitButton.setTitle("Submit", for: .normal)
submitButton.titleLabel?.font = UIFont(name: "Arial", size: 15)
submitButton.titleLabel?.textColor = .white
submitButton.addTarget(self, action: #selector(submit), for: .touchUpInside)
submitButton.layer.cornerRadius = 5
self.view.addSubview(submitButton)
and implement this method:
override func scrollViewDidScroll(_ scrollView: UIScrollView) {
submitButton.frame = CGRect.init(x: submitButton.frame.origin.x, y: UIScreen.main.bounds.size.height + scrollView.contentOffset.y - 50, width: submitButton.frame.width, height: submitButton.frame.height)
}
This works for me:
if let myTopView = Bundle.main.loadNibNamed("MyTopView", owner: self, options: nil)?.first as? MyTopView {
if let view = UIApplication.shared.keyWindow{
view.addSubview(myView);
myTopView.translatesAutoresizingMaskIntoConstraints = false
myTopView.topAnchor.constraint(equalTo: view.topAnchor ).isActive = true
myTopView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
myTopView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
myTopView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
}
}
I want to reuse header section all view controller scene .header section mean green view and label ("AMAR LIFE")
Here is my may 1st view controller scene
Here is my 1st view controller document outline
Subclass UITabBarController. Make the green view a subview of the tab bar controller's main view. Whenever the selected view controller changes (or anything else happens), keep bringing the green view to the front. (Even better, make the green view a layer, not a view, and give it a higher z-position so that it automatically floats in front of all subviews.)
Try the following steps to achieve your header visible on all views.
Step 1: Drag a navigationController into your storyBoard and delete tableView rootViewcontroller comes with the naviagtionController.Connect your NavigationController to your tabBarController.Now,NavigationController available to all your view.
Note: Your storyBoard layout should be look like a below image..
Step 2: Implement following code to your FirstTabBarController.
override func viewDidLoad() {
super.viewDidLoad()
// Apply transparency to NavigationBar.
navigationController?.navigationBar.setBackgroundImage(UIImage(), for: UIBarMetrics.default)
navigationController?.navigationBar.shadowImage = UIImage()
//Setting up scanView background
let barView = UIView(frame: CGRect(x:0, y:0, width:view.frame.width,height: (navigationController?.navigationBar.frame.height)! + UIApplication.shared.statusBarFrame.height))
barView.backgroundColor=UIColor.green // set any colour you want..
barView.layer.borderColor = UIColor.black.cgColor
barView.layer.borderWidth = 3
navigationController?.navigationBar.addSubview(barView)
//Setting up labelView
let label = UILabel()
label.frame = CGRect(x:25, y:5, width:view.frame.width - 50 , height:((navigationController?.navigationBar.frame.height)! + UIApplication.shared.statusBarFrame.height) - 10)
label.text = "AMAR LIFE"
label.textAlignment = .center
label.textColor = .black
label.font = UIFont(name: "HelveticaNeue-medium", size: CGFloat(40))
label.layer.borderColor = UIColor.black.cgColor
label.layer.borderWidth = 3
barView.addSubview(label)
}
Output:
you need to add the following method in every view controller
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
self.navigationController?.isNavigationBarHidden = false
self.navigationController?.navigationBar.setBackgroundImage(#imageLiteral(resourceName: "123"), for: .default)
self.title = "Hi I am tittle"
}
Also if you want to avoid code duplication and do more good just create one parent UIview and write this method in it and then inherit it in all the other views. However both solutions work fine.
you can change the title and image according to your needs.
Thanks
So i am using a custom function to format an subview that I am adding to a UICollectionViewCell. It is from Brian Voong's public project here: https://github.com/purelyswift/facebook_feed_dynamic_cell_content/blob/master/facebookfeed2/ViewController.swift.
func addConstraintsWithFormat(format: String, views: UIView...) {
var viewsDictionary = [String: UIView]()
for (index, view) in views.enumerate() {
let key = "v\(index)"
viewsDictionary[key] = view
view.translatesAutoresizingMaskIntoConstraints = false
}
addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary))
}
What is interesting, is that in my UICollectionView I add a SubView to a single cell, and set the background color to white. The background is white when I comment out the line which sets the background for the subview, and no background color is set when I uncomment out the line setting the visually formatted constraints for the subview.
Here are the two lines which clobber each other:
func chronicleOneClicked(sender: UIButton) {
point1view.backgroundColor = UIColor.whiteColor()
addSubview(point1view)
//When the below is commented the background of point1view disappears
//addConstraintsWithFormat("|-50-[v0]-50-|", views: point1view)
}
when I do print(subviews) i see that the UIView with the white background color is the highest in the view stack (top of the stack). When i print out subviews[subviews.count-1].backgroundColor I get the Optional(UIDeviceWhiteColorSpace 1 1) which is what I expect. it is strange because the color is not displayed.
I am not sure how to go about seeing what is happening behind the scenes to confirm that the background is being set at all in the latter case.
This all happens in a class for the UiCollectionViewCell which I am using as the class of one of my UICollectionView Cells which can be viewed in its entirety here:
https://gist.github.com/ebbnormal/edb79a15dab4797946e0d1f6905c2dd0
Here is a screen shot from both cases, the first case is where the line addConstraintsWithFormat is commented out, and the second case is where it is uncommented: The subview of point1subview is highlighted with a white background in the first case.
This is how I setup the views. It all happens in a class that overrides UICollectionViewCell
class myClass : UICollectionViewCell {
var chronicle: BrowsableChronicle? {
didSet{
//etc.
point1.addTarget(self, action: #selector(chronicleOneClicked(_:)), forControlEvents: UIControlEvents.TouchUpInside)
}
}
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
let point1 : PointButtonView = {
let pointView = PointButtonView(frame: CGRectMake(0, 0, 25, 25 ))
return pointView
}()
//NOTE here is where I create the view, whose background doesn't display
let point1view : UIView = {
let pointView = UIView(frame: CGRectMake( 0, 0, 200, 270))
pointView.backgroundColor = UIColor.whiteColor()
let title = UILabel(frame: CGRectMake(0, 0, 200, 21))
title.font = UIFont(name:"HelveticaNeue-Bold", size: 16.0)
pointView.addSubview(title)
let summary = UILabel(frame: CGRectMake(0, 0, 190, 260))
summary.lineBreakMode = NSLineBreakMode.ByWordWrapping
summary.numberOfLines = 4
summary.font = UIFont(name:"HelveticaNeue", size: 12.5)
pointView.addSubview(summary)
let button = UIButton(frame: CGRectMake(0, 200, 190, 30))
button.backgroundColor = UIColor(red:0.00, green:0.90, blue:0.93, alpha:1.0)
pointView.addSubview(button)
pointView.tag = 100
return pointView
}()
//NOTE: here is where I add the subview to the UICollectionViewCell view
func chronicleOneClicked(sender: UIButton){
addSubview(point1view)
addConstraintsWithFormat("H:|-20-[v0]-20-|", views: point1view)
//TODO anytime i add a constraint here the background color leaves!
print(subviews[subviews.count-1].backgroundColor) //Prints white
}
}
UPDATE: I thought maybe it was related to this issue :
UITableViewCell subview disappears when cell is selected
Where the UICollectionViewCell is selected, and therefore iOS automatically sets the backgroundColor to clear. The problem is, that I implemented this class extension of UIView to see when didSet is called on the backgroundColor and when it is set to clear, i set it to white. However, it only calls didSet on the backgroundColor once, when i first set the color of the view. Here is the code I used to override the UIView class:
class NeverClearView: UIView {
override var backgroundColor: UIColor? {
didSet {
print("background color is being set")
if backgroundColor == UIColor.clearColor() {
print("set to a clear color")
backgroundColor = UIColor.whiteColor()
}
}
}
}
The difference you are seeing is obviously caused by a view frame resulting in zero width or zero height.
Let's explain how the drawing system works.
Every view has a layer that draws its background color in its bounds, which are specified by the view frame. Then every subview is drawn. However, the subviews are not limited by the frame unless you set UIView.clipsToBounds to true.
What you are seeing means the a container view has a zero frame (either width or height) but its subviews have correct frame, therefore they are displayed correctly.
There are multiple reasons why this could happen, for example:
You are setting translatesAutoresizingMaskIntoConstraints to false to some system view (e.g. the content view of the UICollectionView).
You have a constraint conflict, resulting in some important constraint to be removed (you should see a warning).
You are missing some constraints. Specifically, I don't see you setting vertical constraints.
You should be able to debug the problem using the view debugger in Xcode. Just open your app, click the view debugger button and print the recursive description of the cell. You should see a frame that is zero.