How to get scroll views visible rectangle frame after it scrolls in IOS?

Question

I cannot get the coordinates of visible rectangle in scroll view after şt scrolls. So when I want to add a subview in a visible rect, I cannot. How can I do that?

Why can't you? The visible rect has an origin of scrollview.contentOffset size of scrollview.bounds.size — Matt, Sep 26 '13 at 15:25

score 5 · Answer 1 · answered Sep 26 '13 at 16:09

CGRect visibleRect = CGRectMake(myScrollView.contentOffset.x, myScrollView.contentOffset.y, myScrollView.contentOffset.x + myScrollView.bounds.size.width, myScrollView.contentOffset.y + myScrollView.bounds.size.height)

This should get you the rect that is currently visible, after scrolling. Not what you must decide is, when you want to calculate the rect. If you want to get this on the fly, then do it in thescrollViewDidScroll method. If you want to get it when user begins scrolling, then do it in scrollViewWillBeginDragging. If you want it after the user is done scrolling and the scrollView comes to rest, do it in scrollViewDidEndDragging and scrollViewDidEndDecelerating.

The size is incorrect in your answer. You don't add the offset to the size. — Joel, Sep 20 '15 at 23:57

score 3 · Answer 2 · answered Sep 26 '13 at 15:44

3

The visible rect of a scrollView at all time is as below:

CGRectMake(scrollview.contentOffset.x, scrollview.contentOffset.y, scrollview.frame.size.width, scrollview.frame.size.height)

answered Sep 26 '13 at 15:44

dRAGONAIR

1,181
6
8

1

Note, this is correct, but can be simplified to `scrollview.bounds`. For `UIScrollView` the origin of the bounds is the content offset. Also, this is only correct for zoomScale = 1. If zoomed, you must transform the rect to get the correct result. – Joel Sep 21 '15 at 00:12

score 2 · Answer 3 · edited May 23 '17 at 12:02

2

The visible rect for a UIScrollView is myScrollView.bounds. There is no need to use CGRectMake or use the contentOffset property, as the other answers suggest (although it does get you to the same place). However, if the scroll view allows zooming, then you need to transform the rect to account for zooming. A number of solutions for applying the transform are provided in this answer.

edited May 23 '17 at 12:02

Community

1
1

answered Sep 21 '15 at 00:17

Joel

15,654
5
37
60

score 0 · Answer 4 · answered Sep 26 '13 at 15:31

I'm not entirely sure about what you are asking, but if you need to get the content offset as it is being scrolled, you can just use the delegate method:

-(void)scrollViewDidScroll:(UIScrollView *)scrollView

which will be invoked every time the contentOffset changes.

Alternatively you could use

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

to know the contentOffset of the scrollview the seconds it stops decelerating.

Or

-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate

to know the contentOffset of the scrollview when the user stops panning it around.

How to get scroll views visible rectangle frame after it scrolls in IOS?

4 Answers4