Collection View Frame in View Debug is different from code

Question

When debugging custom UICollectionView via View Debug it's width is 829, but when it's width is accessed via code it's width is 820. What am I missing?

Visual debug:

Code:

func collectionView(_ collectionView: UICollectionView, layout: UICollectionViewLayout, sizeForItemAt: IndexPath) -> CGSize
    {
        let widthForCulculation = self.frame.size.width // 820.0
        ...
        return CGSize(width: segmentWidth, height: segmentHeight)
    }

Check spaces between cells look here https://stackoverflow.com/a/35656724/9315978 — a.masri, Jun 14 '18 at 09:33
You should be using `collectionView.bounds.size.width` instead of `self.frame.size.width`. — vacawama, Jun 14 '18 at 09:37
@vacawama : The only difference between bounds and frame is origin, frame's value is calculated with respect to/relative to parentView where as in case of bounds its always calculated relative to itself. hence bounds origin is always 0,0. But no matter which one u use, height n width will always be same. So in this case using frame or bounds will not make any difference. Lemme know if am wrong — Sandeep Bhandari, Jun 14 '18 at 09:45
@SandeepBhandari, that's true if 1) you're looking at the `bound`s and `frame` of the same object, 2) the object is not rotated (if rotated, frame gets wider, but bounds does not change). But, in this case `self` refers to the `view` of the viewController and `collectionView` is one of its subviews so it's not reasonable to always expect them to be the same size. — vacawama, Jun 14 '18 at 09:51
@vacawama self.frame.size.width and collectionView.bounds.size.width are the same — Luda, Jun 14 '18 at 09:54
@vacawama : Ohhh god sorry I did not realize that it was `collectionView.bounds.size.width` I thought u were asking OP to use `self.bounds.size.width` instead of `self.frame.size.width` . Feel so stupid :| But then thank you I did not know on rotation bounds will not change :) Learnt something new :) Thanks — Sandeep Bhandari, Jun 14 '18 at 09:54

score 1 · Accepted Answer · answered Jun 14 '18 at 10:52

Pretty hacky way, but try to invalidate layout when layouting subviews

var width : CGFloat = 0
override func layoutSubviews() {
   super.layoutSubviews()
   if (self.width != self.frame.size.width)
   {
       self.width = self.frame.size.width
       self.collectionViewLayout.invalidateLayout()
   }
}

Collection View Frame in View Debug is different from code

1 Answers1