UIScrollView scroll detection

I have a UIScrollView in a UIViewController view that scrolls horizontally. How can I detect whether the scroll is at the left end or righ开发者_JAVA百科t end or somewhere in the middle?

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You will probably need to look in to a scrollViewDelegate method such as below.

ObjC

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
    NSLog(@"Point: %@", NSStringFromCGPoint(scrollView.contentOffset));
}

Swift

override func scrollViewDidScroll(scrollView: UIScrollView) {
    println(scrollView.contentOffset)
}

Have a look at the apple docs.

Also make sure to set your scrollview delegate your_scroll_view.delegate = self; and your view controller must conform to <UIScrollViewDelegate>

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GameBit is correct here, but to elaborate -

The UIScrollView has a member variable contentOffset, that describes how many pixels from the origin the scrollview has scrolled. A positive value is a scroll to the right, negative is a scroll to the left.

Is your UIScrollView in Paged mode? if so this will help:

 CGFloat pageWidth = scrollView.frame.size.width;
    int page = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;

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This works for me in horizontal UIScrollView

• Conform to UIScrollViewDelegate

• In your ViewController - yourScrollView.delegate = self

  func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
   var currentPage = yourScrollView.contentOffset.x / yourScrollView.bounds.size.width;
  }
  

Do not use scrollViewDidScroll as you need to wait until scrolling ends