Setting UICollectionView frame at runtime

Question

I am trying to set the frame of my UICollectionView at runtime.

I tried using

mainCollectionView.frame = CGRect(x: 20, y: 20, width: self.view.frame.width-20, height: self.view.frame.width-20)

in my viewDidLoad but unfortunately it will always stay as in IB. I am not yet using constraints.

Otherwise resizing my cells is working in cellForItem:

 collectionCell.frame.size.width = self.view.frame.width/8 * 3

Possible duplicate of [How to set UIView size to match parrent without constraints programmatically](http://stackoverflow.com/questions/37725406/how-to-set-uiview-size-to-match-parrent-without-constraints-programmatically) — Yury, Jun 29 '16 at 09:18
The answer was already posted but deleted: it is important to set everything in viewDidLayoutSubviews — JVS, Jun 29 '16 at 09:27
Changing the frame size in the viewDidLoad is not safe because most of the times, view are not fully functional according to the current superview. Instead of viewDidLoad, you change the frame size inside viewWillAppear() or viewDidAppear(). viewDidLayoutSubviews() is the safest place. — ranjit.x.singh, Jun 29 '16 at 09:30

score 2 · Accepted Answer · answered Jun 29 '16 at 09:40

2

Try to set frame in viewDidLayoutSubviews

answered Jun 29 '16 at 09:40

Proton

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Bhadresh Kathiriya · Answer 2 · 2016-06-29T09:34:34.157

1

you are wrong write height because you are set width at height.

try this line without navigation bar:

 mainCollectionView.frame = CGRect(x: 20, y: 20, width: UIScreen.mainScreen().bounds.size.width - (20 * 2), height: UIScreen.mainScreen().bounds.size.height - (20 * 2))

edited Jun 29 '16 at 09:34

answered Jun 29 '16 at 09:23

Bhadresh Kathiriya

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score 0 · Answer 3 · answered Nov 06 '20 at 15:09

Run the following in one of the LayoutSubviews overrides. This will tell collection view to update its frame.

   override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        mainCollectionView.frame = CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height)
        mainCollectionView.collectionViewLayout.invalidateLayout()
    }

Setting UICollectionView frame at runtime

3 Answers3