UIStackView Animation Issue - swift

I have a subStackView inside a stackView and when I hide/show the contents of ONE subStackView, the animation goes all the way up over the other stack views: https://www.youtube.com/watch?v=vKXwX7OpkxU
This is how I create the subStackView. I tried with and without clipToBounds and with an without translatedAutoresizingMaskIntoConstraints. Also tried layoutIfNeeded in the animation part.
let subStackView = UIStackView(arrangedSubviews: [self.innerView[0], self.innerView[1])
subStackView.translatesAutoresizingMaskIntoConstraints = false
subStackView.axis = .vertical
subStackView.distribution = .fillEqually
subStackView.alignment = .fill
subStackView.spacing = 0
subStackView.clipsToBounds = true
This subStackView is then loaded into a mainStackView which results in the issue.

One way to fix your problem is to control more directly how the purple view is shown and hidden. What you're doing now (I assume) is setting isHidden property to true and then letting the stack view do whatever it wants. Instead, let's put the purple view inside a container view, and animate the container view's height down to zero. Then it can look like this:
The reason to use a container view instead of just animating the purple view's height directly is that you might (in general) have other constraints controlling the purple view's height, so also constraining its height to zero would fill up your console with unsatisfiable constraint errors.
So here's what I did for the demo. I made a “Hello, world!” label with a purple background. I constrained its height to 80. I put the label inside a container view (just a plain UIView). I constrained the top, leading, and trailing edges of the label to the container view, as normal. I also constrained the bottom edge of the label to the container view, but at priority 999* (which is less than the default, “required” priority of 1000). This means that the container view will try very hard to be the same size as the label, but if the container view is forced to change height, it will do so without affecting the label's height.
The container also has clipsToBounds set, so if the container becomes shorter than the label, the bottom part of the label is hidden.
To toggle the visibility of the label, I activate or deactivate a required-priority height constraint on the container view that sets its height to zero. Then I ask the window to lay out its children, inside an animation block.
In my demo, I also have the stack view's spacing set to 12. If I just leave the container view “visible” (not isHidden) with a height of zero, the stack view will put 12 points of space after the button, which can look incorrect. On iOS 11 and later, I fix this by setting a custom spacing of 0 after the button when I “hide” the container, and restore the default spacing when I “show” it.
On iOS version before iOS 11, I just go ahead and really hide the container (setting its isHidden to true) after the hiding animation completes. And I show the container (setting its isHidden to false) before running the showing animation. This results in a little bump as the spacing instantly disappears or reappears, but it's not too bad.
Handling the stack view spacing makes the code substantially bigger, so if you're not using spacing in your stack view, you can use simpler code.
Anyway, here's my code:
class TaskletViewController: UIViewController {
#IBAction func buttonWasTapped() {
if detailContainerHideConstraint == nil {
detailContainerHideConstraint = detailContainer.heightAnchor.constraint(equalToConstant: 0)
}
let wantHidden = !(detailContainerHideConstraint?.isActive ?? false)
if wantHidden {
UIView.animate(withDuration: 0.25, animations: {
if #available(iOS 11.0, *) {
self.stackView.setCustomSpacing(0, after: self.button)
}
self.detailContainerHideConstraint?.isActive = true
self.view.window?.layoutIfNeeded()
}, completion: { _ in
if #available(iOS 11.0, *) { } else {
self.detailContainer.isHidden = true
}
})
} else {
if #available(iOS 11.0, *) { } else {
detailContainer.isHidden = false
}
UIView.animate(withDuration: 0.25, animations: {
if #available(iOS 11.0, *) {
self.stackView.setCustomSpacing(self.stackView.spacing, after: self.button)
}
self.detailContainerHideConstraint?.isActive = false
self.view.window?.layoutIfNeeded()
})
}
}
override func loadView() {
stackView.axis = .vertical
stackView.spacing = 12
stackView.translatesAutoresizingMaskIntoConstraints = false
button.translatesAutoresizingMaskIntoConstraints = false
button.backgroundColor = UIColor.green.withAlphaComponent(0.2)
button.setTitle("Tap to toggle", for: .normal)
button.addTarget(self, action: #selector(buttonWasTapped), for: .touchUpInside)
button.setContentHuggingPriority(.required, for: .vertical)
button.setContentCompressionResistancePriority(.required, for: .vertical)
stackView.addArrangedSubview(button)
detailLabel.translatesAutoresizingMaskIntoConstraints = false
detailLabel.text = "Hello, world!"
detailLabel.textAlignment = .center
detailLabel.backgroundColor = UIColor.purple.withAlphaComponent(0.2)
detailLabel.heightAnchor.constraint(equalToConstant: 80).isActive = true
detailContainer.translatesAutoresizingMaskIntoConstraints = false
detailContainer.clipsToBounds = true
detailContainer.addSubview(detailLabel)
let bottomConstraint = detailLabel.bottomAnchor.constraint(equalTo: detailContainer.bottomAnchor)
bottomConstraint.priority = .init(999)
NSLayoutConstraint.activate([
detailLabel.topAnchor.constraint(equalTo: detailContainer.topAnchor),
detailLabel.leadingAnchor.constraint(equalTo: detailContainer.leadingAnchor),
detailLabel.trailingAnchor.constraint(equalTo: detailContainer.trailingAnchor),
bottomConstraint
])
stackView.addArrangedSubview(detailContainer)
self.view = stackView
}
private let stackView = UIStackView()
private let button = UIButton(type: .roundedRect)
private let detailLabel = UILabel()
private let detailContainer = UIView()
private var detailContainerHideConstraint: NSLayoutConstraint?
}

Related

Swift: Make the background image of UITableViewController embedded in Navigation Controller fill the entire screen

I managed to create translucent and rounded UITableViewCells in a UITableViewController that is embedded inside a Navigation Controller with this line of code in viewDidLoad():
tableView.backgroundView = UIImageView(image: UIImage(named: "nightTokyo"))
But I want the background image to fill the entire phone screen. I changed the code (and only this line of code) to:
navigationController?.view = UIImageView(image: UIImage(named: "nightTokyo"))
Now the background image fills up the entire phone screen, but my table and even the iPhone's time and battery indicator icons are missing.
What I want is for the background image to fill the entire screen, but the tableView, its cells, the iPhone time, battery level icon, etc. to remain displayed.
navigationController?.setNavigationBarHidden(true, animated: true)
Here is what I did which worked for me using Swift 5, XCode 12.
Step 1 (Optional) - Create a custom UINavigationController class
class CustomNavigationController: UINavigationController {
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
navigationBar.isTranslucent = true
}
Replace your UINavigationController with this UINavigationController subclass. I mark this as optional as this is based on preference, if you do not set this, your navigation bar will be opaque and you cannot see what's beneath it.
Setting the navigationBar.isTranslucent = true allows you to see the background beneath it which is what I like. A subclass is also optional but you might need to make other updates to your nav bar so I always like to make this a subclass.
Step 2 - Set up your background view constraints
class CustomViewController: UIViewController {
// your background view
let bgImageView: UIImageView = {
let bgImageView = UIImageView()
bgImageView.image = UIImage(named: "gradient_background")
bgImageView.contentMode = .scaleAspectFill
return bgImageView
}()
// Get the height of the nav bar and the status bar so you
// know how far up your background needs to go
var topBarHeight: CGFloat {
var top = self.navigationController?.navigationBar.frame.height ?? 0.0
if #available(iOS 13.0, *) {
top += UIApplication.shared.windows.first?.windowScene?.statusBarManager?.statusBarFrame.height ?? 0
} else {
top += UIApplication.shared.statusBarFrame.height
}
return top
}
var isLayoutConfigured = false
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
title = "Site Visit"
// you only want to do this once
if !isLayoutConfigured() {
isLayoutConfigured = true
configBackground()
}
}
private func configBackground() {
view.addSubview(bgImageView)
configureBackgroundConstraints()
}
// Set up your constraints, main one here is the top constraint
private func configureBackgroundConstraints() {
bgImageView.translatesAutoresizingMaskIntoConstraints = false
bgImageView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor,
constant: -topBarHeight).isActive = true
bgImageView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor,
constant: 0).isActive = true
bgImageView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor,
constant: 0).isActive = true
bgImageView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor,
constant: 0).isActive = true
view.layoutIfNeeded()
}
Before setting constraints:
After setting above constraints:

UIStackView and a placeholder view in another UIStackView problem

There is a problem if you have a UIStackView(testStack) and a placeholder UIView(testView) inside another UIStackView(mainStack). It is meant that if there is no content in the testStack it will collapse, and the testView will take all the space. There is even a content hugging priority set to maximum for the testStack so it should collapse its height to 0 when there are no subviews. But it does not. How to make it collapse when there is no content?
PS If there are items in the testStack, everything works as expected: testView takes all available space, testStack takes only the space to fit its subviews.
class AView: UIView {
lazy var mainStack: UIStackView = {
let stack = UIStackView()
stack.axis = .vertical
stack.backgroundColor = .gray
stack.addArrangedSubview(self.testStack)
stack.addArrangedSubview(self.testView)
return stack
}()
let testStack: UIStackView = {
let stack = UIStackView()
stack.backgroundColor = .blue
stack.setContentHuggingPriority(.init(1000), for: .vertical)
return stack
}()
let testView: UIView = {
let view = UIView()
view.backgroundColor = .red
return view
}()
init() {
super.init(frame: .zero)
backgroundColor = .yellow
addSubview(mainStack)
mainStack.translatesAutoresizingMaskIntoConstraints = false
mainStack.topAnchor.constraint(equalTo: topAnchor).isActive = true
mainStack.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
mainStack.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true
mainStack.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
When auto-layout arranges subviews in a UIStackView, it looks at:
the stack view's .distribution property
the subviews' height constraints (if given)
the subviews' Intrinsic Content Size
Since you have not specified a .distribution property, mainStack is using the default of .fill.
A UIStackView has NO Intrinsic Content Size, so auto-layout says "testStack has a height of Zero"
A UIView has NO Intrinsic Content Size, so auto-layout says "testView has a height of Zero"
Since the distribution is fill, auto-layout effectively says: "the heights of the arranged subviews are ambiguous, so let's give the last subview a height of Zero, and fill mainStack with the first subview.
Setting .setContentHuggingPriority will have no effect, because there is no intrinsic height to "hug."
If you set mainStack's .distribution = .fillEqually, you will get (as expected) testStack filling the top half, and testView filling the bottom half.
If you set mainStack's .distribution = .fillProportionally, you will get the same result... testStack filling the top half, and testView filling the bottom half, because .fillProportionally uses the arranged subviews' Intrinsic Content Sizes... in this case, they are both Zero, so "proportional" will be equal.
If you set mainStack's .distribution = .equalSpacing or .distribution = .equalCentering, you won't see either testStack or testView ... auto-layout will give each of them a height of Zero, and fill the rest of mainStack with (empty) "spacing."
If your goal is to have testStack "disappear" if it is empty, you can either:
set it hidden, or
subclass it and give it an intrinsic height

UITapGestureRecognizer works first time, but not second time

[Greatly simplified]
I'm following a "Let's Build That App" YouTube series on Firebase 3. It's from 2016, so I've had to rework some of the code since Swift has evolved since then, but mostly it's a useful tutorial.
But, I'm stuck on something.
The red box is intended to be a custom titleView with an Image and Name, but I've simplified it to try to find the problem.
viewWillAppear calls setupNavbar which sets up the navbar.titleView:
func setupNavbar() {
let titleView = UIView()
titleView.frame = CGRect(x: 0, y: 0, width: 300, height: 40)
titleView.backgroundColor = .red
let containerView = UIView() // for the Image and Label, later
containerView.translatesAutoresizingMaskIntoConstraints = false
containerView.backgroundColor = .green
// left, top, width, height anchors equal to same for titleView
containerView.leftAnchor.constraint(equalTo: titleView.leftAnchor)
// top, width, height are similar
titleView.addSubview(containerView)
self.navigationItem.titleView = titleView
let recognizer = UITapGestureRecognizer(target: self, action: #selector(showChatController))
titleView.addGestureRecognizer(recognizer)
}
The selector's function is:
#objc func showChatController() {
let chatController = ChatLogTableViewController()
navigationController?.pushViewController(chatController, animated: true)
}
The class ChatLogTableViewController has just the default viewDidLoad().
First, I'm surprised the box is red, and not green. Why is that?
Second, if I click the red box, the ChatController is loaded, as expected. But, when I click "Back" and return to this screen, the red box is not visible, thus I can no longer tap on it. BUT....If I sign out and sign in/up again, the box is red and I can click it again.
What am I missing?
Update 1: The "+" creates a new controller and presents it.
present(UINavigationController(
rootViewController: NewMessageTableViewController()),
animated: true,
completion: nil)
That controller is currently empty, except for a leftBarButtonItem which is just a barButtonSystemItem (.cancel). Just like "Sign Out", this also "resets" the gesture and it works.
Update 2: Code added upon request.
Update 3: question greatly simplified. Also, if I change the showChatController code to just print ("show Chat Controller"), I can click to my heart's content; the red box and its tap gesture both remain.
So, there is something happening when I ...pushViewController and then come back.
Have you tried to set isUserInteractionEnabled property of the label which you set as the navBar's titleView? I know it's silly but I've missed this a lot of times :)
let recognizer = UITapGestureRecognizer(target: self, action: #selector(YourViewController.titleWasTapped))
titleView.isUserInteractionEnabled = true
titleView.addGestureRecognizer(recognizer)
you can try following things:
1. "User Interaction Enabled" in the UILabel Attributes Inspector in the Storyboard.
2. override func viewDidLoad(animated: Bool) {
super.viewDidAppear(animated)
self.titleView.userInteractionEnabled = true
var tapGesture = titleView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(showChatController)))
self.titleView.addGestureRecognizer(tapGesture)
}
func showChatController() {
println("Tap Gesture recognized")
}
Hi #Zonker I've tested your setupNavBar(). It's working fine nothing worng with your code when I press and go back clicking titleView. Reason why you're not getting .green color is you have to give height and width for containerView and big reason is you've put addSubView code below the anchor and there is no .isActive = true in your containerView.leftAnchor.constraint... Please check setupNavBar() code below:
func setupNavbar() {
let titleView = UIView()
titleView.frame = CGRect(x: 0, y: 0, width: 300, height: 40)
titleView.backgroundColor = .red
let containerView = UIView() // for the Image and Label, later
containerView.translatesAutoresizingMaskIntoConstraints = false
containerView.backgroundColor = .green
titleView.addSubview(containerView)
// left, top, width, height anchors equal to same for titleView
containerView.widthAnchor.constraint(equalToConstant: 300).isActive = true
containerView.heightAnchor.constraint(equalToConstant: 40).isActive = true
containerView.leftAnchor.constraint(equalTo: titleView.leftAnchor).isActive = true
// top, width, height are similar
self.navigationItem.titleView = titleView
let recognizer = UITapGestureRecognizer(target: self, action: #selector(showChatController))
titleView.addGestureRecognizer(recognizer)
}
It would better if you push your code in github so we can test your code

Snapkit centerY constraint centers item above the center Y axis

I'm trying to make a custom UICollectionView cell class. The cell consists of a content view and a label. I want the label to be in the center of the view, horizontally and vertically, but instead the label is placed above the content view's center y axis.
I've made sure that the constraints are set, no other constraints are being set, and that the issue affects all views in the content view (I added another view and set its center Y axis as a test, and that also didn't work). I also set the content view and the label's background colors to be contrasting, and have confirmed that the label is not lying on the content view's center y anchor.
Here is how I set the consraints:
label.snp.makeConstraints{make in
make.centerX.centerY.equalToSuperview()
}
Here is what I get instead. Clearly the label is not centered vertically. You can see the blue UIView, which I added as a test, is also not centered vertically.
I used to add my constraints programmatically in this way
self.view.addSubview(image)
image.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
image.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
image.heightAnchor.constraint(equalToConstant: 30).isActive = true
image.widthAnchor.constraint(equalToConstant: 30).isActive = true
and my image is declarated in this way
let image: UIImageView = {
let theImageView = UIImageView()
theImageView.image = UIImage(named: "ico_return")
theImageView.translatesAutoresizingMaskIntoConstraints = false
return theImageView
}()
Hope it helps
Can you try Following Code.
class FilterCollectionViewCell: UICollectionViewCell {
let labelTemp = UILabel()
override func awakeFromNib() {
labelTemp.backgroundColor = .white
labelTemp.textColor = .black
labelTemp.text = "testing"
self.contentView.addSubview(labelTemp)
labelTemp.snp.makeConstraints { (make) in
make.centerX.centerY.equalTo(self.contentView)
}
}
}
Fast and easy:
myLabel.snp.makeConstraints { (make) in
make.center.equalTo(self.topView.snp.center)
}

Swift 4 upgrade issue with imageViews as bar buttons within navigation bar

So I have upgraded to swift 4 and now my left & right uiimageviews set as left/right nav button items are showing as large icons. I have figured out that the Frame setting is not being applied and I am not sure why.
Does anyone know what may cause this?
Here is some code
lazy var leftBarPic: UIImageView = {
let pic = UIImageView(frame: CGRect(x: 0, y: 0, width: 25, height: 25))
pic.clipsToBounds = true
pic.contentMode = .scaleAspectFit
pic.image = myImage.withRenderingMode(.alwaysOriginal)
pic.isUserInteractionEnabled = true
pic.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(postNewsAction)))
pic.backgroundColor = .green
return pic
}()
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.leftBarButtonItem = UIBarButtonItem(customView: leftBarPic)
}
OK I found a fix. For anyone having similar, what I did was add the property (in this instance the left navigator imageView) to the view's subview. Then added the constraints for width and height. It seems that with the upgrade setting the frame for nav items (image views only) inside the property does not work.