To make proper animation of a uiview with constraints u must set the new constraint value and then call theView.layoutIfNeeded() , for swift 3 this doesnt work and instead of calling from the view's whos constraint is changed . it must be called from the upper view like this : self.view.layoutIfNeeded().
ex :
UIView.animate(withDuration: 0.1,
delay: 0.1,
options: UIViewAnimationOptions.curveEaseIn,
animations: { () -> Void in
constraintHeight.constant = 10.00
// instead of myView.layoutIfNeeded() // Swift 2
self.view.layoutIfNeeded() // Swift 3
}, completion: { (finished) -> Void in
// ....
})
The problem is, in my case i did the change and the way im using this animation is for a bottomview (a bottom bar/ banner view) that hides when scrolling a tableview down and comes up when going all the way to the top in the tableview. now that i have changed the proper code for swift 3 using self.view.layoutIfNeeded() , the tableview acts wierd, slows down, rows start appearing as fading in or is just way slow to present, when scrolling down and up the tableview's sections comes jumping or moving in slow motion, also have seem memory gone up from 80mb to 100mb . if i eliminate the line in the code, i dont get the animation, the view just appears and dissapears with the scrolling of the tableview, but... i dont get the strange behavior. i have also checked the views hierarchy to check somehow is not creating wierd 100 views replicating or something.. any hints on how can i fix this . all of this was just working fine in swift 2 using theView.layoutIfneeded() but now that the call is being madein the upper view.. omg..wierd acting
Question comes from Swift 3 UIView animation solution.
Try this to force layout changes to superview
//Force to complete all changes.
self.view.superview.layoutIfNeeded()
//Update constant
constraintHeight.constant = 10.00
UIView.animate(withDuration: 0.1,
delay: 0.1,
options: UIViewAnimationOptions.curveEaseIn,
animations: { () -> Void in
self.view.superview.layoutIfNeeded()
}, completion: { (finished) -> Void in
// ....
})
Solution to my needs . thanks all for sharing your answers!.
my view hierarchy
- root view
- uitableView
- bottomBarView
- bottomBannerView
Beacause of that hierarchy i couldnt use self.view.layoutIfNeeded() or self.bottomBarView.superview?.layoutIfneeded(), as it was calling to layout the same superview which also host the tableview and for which im triggering this function if scrolling is more than 10 and also if it less.. so its always trigerring the layoufIfneededmethod. i had to do what i thought from the beginning.
The correct way is to make a container view hosting the bottombarview and the banner view, have it constraint to bottom of the root super view and constraint the bottomBarView and bottomBannerView to IT.
View hierarchy now is .
-root view
-uitableView
-containerBottomView
-bottomBarView
-bottomBannerView
This way i can call self.bottomBarView.superview?.layoutIfNeeded() , and it wont be triggering on the root view which also host the uitableview. it correctly triggers to layout the containerBottomView.
UIView.animate(withDuration: 0.5, delay: 0.3, options: [.repeat, .curveEaseOut, .autoreverse], animations: {
// perform your animation here .
self.username.center.x += self.view.bounds.width
self.view.layoutIfNeeded()
}, completion: nil)
Related
I am animating my constraints using UIView.animate. drawerHeight is a constraint variable.
Here is the code:
drawerHeight?.constant = newHeight
UIView.animate(withDuration: 0.35, delay: 0, usingSpringWithDamping: 0.65, initialSpringVelocity: 2, options: .allowUserInteraction, animations: {
self.superview?.layoutIfNeeded()
})
Here is a video of what the issue looks like.
Looking at the bottom of the video, the bottom edge appears to lag behind. Why do these constraints seem to lag when animated?
This is a self-answered question. This post is to help people in the future discover what they did wrong, and how to quickly fix it.
The issue was that the constraint was attached to a view in a deeper hierarchy than before. When using layoutIfNeeded(), it should be called on the superview of the view containing the constraints.
In my situation, I put the view with the drawerHeight constraint within another UIView, which made it deeper in the hierarchy.
I fixed the issue by doing
self.superview?.superview?.layoutIfNeeded() ,
instead of
self.superview?.layoutIfNeeded() .
I'm trying to animate a view that is constrained (iconVerticalConstraint) to be at center Y (+100) of a superview, specifically reaching its right (0) position after an animation.
Here's my code:
self.view.layoutIfNeeded()
UIView.animateKeyframes(withDuration: 2, delay: 0, animations: {
UIView.addKeyframe(withRelativeStartTime: 0.0, relativeDuration: 0.25, animations:{
self.iconVerticalConstraint.constant -= 20
})
UIView.addKeyframe(withRelativeStartTime: 0.25, relativeDuration: 0.75, animations:{
self.iconVerticalConstraint.constant -= 80
})
})
I tried following this question's answer but that didn't help, because in my case my view contains more subviews, intrinsically linked, and putting layoutIfNeeded() in my animation block would animate the whole view, and not just that constraint. Otherwise this approach does no animation at all.
changing constraints such as
self.iconVerticalConstraint.constant -= 20
should be OUTSIDE the animation block and inside you just call
self.view.layoutIfNeeded()
I think because you are trying to do 2, and calling
self.view.layoutIfNeeded()
They all happen once, consider changing to:
self.iconVerticalConstraint.constant -= 20
UIView.animate(withDuration: 0.25, animations: {
self.view.layoutIfNeeded()
}) { (finished) in
self.iconVerticalConstraint.constant -= 80
UIView.animate(withDuration: 0.75, animations: {
self.view.layoutIfNeeded()
}, completion: nil)
}
Edit: Explanation
When you change a constraint, the view will not update until the next layout cycle, usually when you exit your current scope. So when you want to animate a constraint, you change the constant BEFORE the animation block, then inside the animation block you call layoutIfNeeded() This tells it to animate the now forced layout cycle.
Now in your example, you where calling layoutIfNeeded() which would do nothing at that point, then changing 2 constants, without telling the layout to animate, so when the scope exited, the UI would layout without animation.
In your case you want to chain the changing of 2 constants, but you dont have a way of changing the second constant (80) after the first animation completes, and if you set both, both constants will be adjusted on the FIRST layoutIfNeeded() hence, the chaining of animations, which will still work with your other animations that you omitted, just add then in the first animation block if they are in the first keyframe and the second if they were in the second.
Final Edit:
Also you can change your layoutIfNeeded() currently applied to self.view to actually on the views it affects, in this case iconVerticalConstraint if it was a view that is attached to another view say a top attached to a view bottom, if you wanna animate, you must call layoutIfNeeded() on each view it affects
After hours of time spent to understand the basic mechanism, I can provide my own answer, for all of you who will find themselves in my situation.
layoutIfNeeded() tells to the view to adjust position of all of its subviews.
animate or animateKeyframes or every other alternative you're using, instead, tells to the view to perform any of the instructions inside the animation block in the way you specify in the animate function (by default, with a options: .easeInOut)
Back to the question: the problem was in the fact that animate and layoutIfNeeded are called asynchronously so that, in fact, every instruction inside the animation block was executed just before the layoutIfNeeded instruction, making it useless. The solution isn't putting the layoutIfNeeded instruction inside the animation block, as suggested by SeanLintern88 because in this way we would tell the view to adjust the position of its subviews according to the animation options. That's the key point.
The answer is somewhat simple. Move the animation part on the subview itself, specifically in a point when you know that the superview has already been "autolayouted" (e.g. viewDidAppear), so that the constraint is already defined and executed, and you can now change it. In that point, code should look like this:
UIView.animateKeyframes(withDuration: 2, delay: 0, animations: {
self.view.layoutIfNeeded()
UIView.addKeyframe(withRelativeStartTime: 0.0, relativeDuration: 0.25, animations:{
self.iconVerticalConstraint.constant -= 20
})
UIView.addKeyframe(withRelativeStartTime: 0.25, relativeDuration: 0.75, animations:{
self.iconVerticalConstraint.constant -= 80
})
})
Because you want to animate the autolayout.
Another option (for instance, if you haven't/don't want to create a class for your subview) is to change bounds/center of the subview itself in the viewDidAppear function of the parent view. This is because, if you are in the parent view, you know that at that point auto layout has already been registered but not executed, in the more precise sense that bounds and center have been already changed according to the auto layout.
If you then change them, you'll obtain your desired animation (but remember: auto layout is still on, so you must change the constraints in a way that reflects the final position of your animation; if you wish, you can do that in the completion part of animate function).
I'm currently working on a iOS (swift 3) app. I have a simple vertical stack view containing 2 horizontal stack views. In some cases I want to hide the bottom one. I do so by using the following code
UIView.animate(withDuration: 3) {
self.bottomStackView.isHidden = true;
};
The animation shown below doesn't really do what I would expect:
While the border of the buttons is animated properly when hiding, the text inside each button doesn't seem to be affected until the very end. Any idea as to how I could fix this?
I kept doing some research on the subject, and it seems like most articles were suggesting that using stacks to perform animation would work fine. However I have also found that animations would only work with animatable properties, isHidden not being one of them.
In the end after some trial and errors I have found that isHidden can be animated with stack views, but you can expect children to misbehave. So far the only workaround I have found is like so:
let duration = 0.5;
let delay = 0;
UIView.animate(withDuration: duration, delay: delay, animations: {
self.bottomStack.isHidden = self.hideBottomStack;
})
UIView.animate(withDuration: duration/2, delay: delay, animations: {
self.bottomStack.alpha = 0;
})
You'll note here that I basically "turn" the alpha property down to 0 in half the time I take to hide the stack. This has the effect to hide the text before it overlaps with the upper stack. Also note that I could also have decided to do something like this:
UIView.animate(withDuration: duration, delay: delay, animations: {
self.bottomStack.alpha = 0;
}, completion: { (_) in
self.bottomStack.isHidden = true;
})
This would also hide the bottom stack, but you lose the hiding motion in favor of a fading motion and hide the stack once the fading is done.
I'm not sure about this, I think stackviews can cause weird behaviour sometimes. Have you tried adding "self.view.layoutIfNeeded()" inside the UIView.animate block? Like this:
UIView.animate(withDuration: 3) {
self.bottomStackView.isHidden = true
self.view.layoutIfNeeded()
}
I think it should also work if you put the "self.bottomStackView.isHidden = true" above the UIView.animate, not sure though, not an expert at it.
Also, I don't think you need to use ";" after your line of code in swift :)
I'm making an app in swift using Xcode and I'm having troubles with the animation of some button.
Here's my situation:
I have three buttons in the middle of the screen where i've also added some constraints.
What i need is that when the button is clicked it reaches the top of the screen, like in this second photo with an animation:
I've tried this:
UIView.animateWithDuration(1, delay: 0, options: [], animations: {
self.Button2.center.y = 18 + self.Button2.frame.height/2
}, completion: nil)
But what happens is that the button appears from the bottom of the screen slides up to the position of the first photo. It doesn't respect the position I wrote in the animation. Is it possibile that this is due to the constraints? Because I centered it vertically and horizontally.
Can you help me to make it work?
When you work with autolayout and constraints you never make changes to the button frame in your animation, like your code: you must work always with constraints.
This is a generic example:
myButtonCenterYConstraint.constant = 200.0
myButton.layoutIfNeeded()
UIView.animateWithDuration(Double(0.5), animations: {
myButtonCenterYConstraint.constant = 0
myButton.layoutIfNeeded()
})
So, the first step is to declare the button constraints you will want to change as IBOutlets:
First get the center y of the button then reposition the button.
float centerY = self.Button2.center.y;
UIView.animateWithDuration(1, delay: 0, options: [], animations: {
self.Button2.center.y = centerY + 18 + self.Button2.frame.height/2
}, completion: nil)
You must change the constraint first and then update the UI in animation. Something like this.
yourButton.yourOriginConstraint'sYCoordinate.constant = // Set this to what you want to change.
// yes, you should create an IBOutlet for constraint that you want to modify.
UIView.animateWithDuration(1.0, animations: {
self.view.layoutIfNeeded()
}, completion: nil)
Another way is to not user auto layout.
Here, is the reference
I'm struggling to figure out how to allow user interaction with a view as it's being animated.
Here's the situation: I have a UIView cardView which holds card subviews. The cards are draggable tiles, similar to how the cards in Tinder are draggable/swipeable.
I am trying to fade out the card using animateWithDuration by animating to cardView.alpha = 0. Logically, this will also fade out all of the subviews (card objects). In this specific case, I am only targeting one card subview. However, during the animation, I am unable to drag/interact with the card.
Here is the code I'm using:
UIView.animateWithDuration(
duration,
delay: 0,
options: UIViewAnimationOptions.AllowUserInteraction,
animations: {self.cardView.alpha = 0}
) {
_ in
println("Card faded out")
card.removeFromSuperview()
}
Why doesn't this work? Any help will be appreciated. Thank you!!
I think you can find the answer in this previous post.
The interesting bit of the post is:
UIView's block animation by default blocks user interaction, and to get around it you need to pass UIViewAnimationOptionAllowUserInteraction as one of the options.
I fixed this problem by setting alpha to 0.1 instead of 0.0. I'm not sure if that will work in your case, but it shows that the event handling code thought that the view was not visible and disabled interaction even with the UIViewAnimationOptionAllowUserInteraction flag set. Oddly, setting the alpha to 0.01 did not work, so there is a threshold of visibility you have to stay above.
Swift 5
UIView.animateKeyframes(withDuration: 0.5, delay: 0, options: [.repeat, .autoreverse, .allowUserInteraction], animations: {
self.customButton.backgroundColor = .none
}, completion: nil)
The issue is with the Alpha value of 0. Alpha values of a certain proximity to Zero will remove the view from the view responder hierarchy. The fix here is to make the alpha setting to this:
self.cardView.alpha = 0.011
The view will still be invisible but not removed from the responder chain. From my testing the minimum amount is the following:
extension CGFloat {
static let minAlphaForTouchInput: CGFloat = 0.010000001
}