iOS UIScrollView滚动检测

Question

I'm developing kind of UITextView copy with customizations. For now I need to implement selection cursors (see screenshot of original UITextView below)

As I discovered from Debug View Hierarchy Apple developers draw these dots on separate Window to avoid clipping, and when UIScrollView starts dragging they move these dots inside UITextView , when it stops dragging they move it back to separate window. The only problem with this approach is how can I detect when some of my TextView superview 's are UIScrollView and they start/end scrolling? Setting delegate for each of UIScrollView -type superviews looks bad and will bring a lot of headache, cause I will need to manage several delegates if needed (and even detect there change). Any ideas?

Answer 1

You can use the same scroll view delegate for all UIScrollViews.

scrollView1.delegate = self
scrollView2.delegate = self
etc...

Just implement the delegate methods and take different action if necessary for each scroll view. Either do this by referencing properties in the class or setting the tag.

func scrollViewDidScroll(scrollView: UIScrollView!) {
   if scrollView.tag == 0 {
     // Do stuff
   } else {
     // Do other stuff
   }
}

Answer 2

/*
 In your viewDidLoad or where ever you create the UITextView call this :[self checkParentViewOfTextView:textField];
*/

-(void)checkParentViewOfTextView:(UITextView*)txv {
    if ([txv.superview isKindOfClass:[UIScrollView class]]) { // Check if the superview if UIScrollView
        UIScrollView *superScroll =(UIScrollView*) txv.superview;
        superScroll.delegate = self;// In order to call the delegate methods below
        superScroll.tag = 5; // Set a tag to access the current scrollView at these delegate methods
    }
}
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
    //Any scrollView did begin scrolling
    if (scrollView.tag == 5) {
        //Actions for your scrollView
    }
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    //Any scrollView did end scrolling
    if (scrollView.tag == 5) {
        //Actions for your scrollView
    }
}