Auto-Layout animation takes center as anchoring point

Question

I have an height animation based on constraints. However when animation starts it takes view's center as anchoring point not the top.

I want it to animate as fixed top and shrinking from the bottom.

Sorry for my English not a native speaker.

my views anchors:

top: superview
left: superview
right: superview
bottom: nil

// current height constant 200
view.height.constant = 0

UIView.animation(withDuration: 0.2, animations: {
    view.layoutIfNeded()
}}

Jess · Accepted Answer · 2017-07-27T07:50:37.340

10

Try instead of your view:

superView.layoutIfNeeded()

this will layout the subview and your animation should work.

so replace

    // current height constant 200
view.height.constant = 0

UIView.animation(withDuration: 0.2, animations: {
    view.layoutIfNeded()
}

with

    // current height constant 200
yourView.height.constant = 0

UIView.animation(withDuration: 0.2, animations: {
    yourViewSuperview.layoutIfNeded()
}

see layoutIfNeeded() apple docs: [1]https://developer.apple.com/documentation/uikit/uiview/1622507-layoutifneeded

edited Jul 27 '17 at 07:50

answered Jul 27 '17 at 07:44

Jess

1,394
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12

Amazing thank you! I was using super.layoutIfNeeded but superview fixed all my problems. – Jack Dewhurst Feb 01 '19 at 14:24

Abhishek Jain · Answer 2 · 2017-07-27T07:42:43.050

0

Change code

// current height constant 200
view.height.constant = 0

UIView.animation(withDuration: 0.2, animations: {
    view.layoutIfNeded()
}}

to

UIView.animate(withDuration: 2.0, animations: {
// current height constant 200
view.height.constant = 0
}}

Hope it helps!

edited Jul 27 '17 at 07:42

answered Jul 27 '17 at 07:32

Abhishek Jain

4,557
2
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Its not actually animating but thats okay right now :) – Tunahan Bayındır Jul 27 '17 at 07:36
Its not meeting the needs, sorry. Also changing constant in animate func does nothing btw – Tunahan Bayındır Jul 27 '17 at 14:42

Auto-Layout animation takes center as anchoring point

2 Answers2