UIScrollView inside UIScrollView

Question

I have a UIScrollView with another UIScrollView inside. They both are scrolled horizontally and have pagingEnabled = YES. Assume that I started to scroll inner scroll view and reached the most right bound. And if I proceed scrolling in it, then the outer scrollView begins to move. I need to avoid this. Inner view should jump with rubber-band effect, outer should stay at it's place.

Hope it's clear, but here is a sketch:

I've tried to set outerView.scrollEnabled = NO; like this:

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    outerView.scrollEnabled = NO;
}

, and it works exactly how I need, if to scroll just in innerView. OuterView is not scrolled anymore. But I have to set scrollEnabled back to YES somewhere for the case if I'd want to scroll outerView again. I've tried to do it here:

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    outerView.scrollEnabled = YES;
}

, but than I'm getting the same problem: after reaching the the most right bound of innerView outerView scrolls instead of innerView jumps with rubber-band effect.

Any suggestions how to solve a problem?

Answer 1

UPDATE

This solution works always:

@implementation InnerScrollViewController <UIScrollViewDelegate, UIGestureRecognizerDelegate>

- (void)viewDidLoad
{
    UISwipeGestureRecognizer*   swipeGesture = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)] autorelease];
    swipeGesture.delegate = self;
    [self.view addGestureRecognizer:swipeGesture];
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
    _outerScrollView.scrollEnabled = NO;
    return YES;
}

- (void)handleSwipe:(UIGestureRecognizer*)gestureRecognizer
{

}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{   
    _outerScrollView.scrollEnabled = NO;
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    if (!decelerate)
    {
        _outerScrollView.scrollEnabled = YES;
    }
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    _outerScrollView.scrollEnabled = YES;
}

@end

-----------------------------------------------------------------------

OLD ANSWER: doesn't work always

Here is how I solved the problem:

@implementation InnerView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.delaysContentTouches = NO;
    }
    return self;
}

- (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view
{
    return NO;
}

As I understand, self.delaysContentTouches = NO; makes all events to be delivered immediately, and - (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view prevents passing of these events by responder chain.

Answer 2

Modify your methods by below way:

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    if(scrollView == innerView)
        outerView.scrollEnabled = NO;
    else
        outerView.scrollEnabled = YES;
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    if(scrollView == innerView)
    {
         if(innerView.contentOffset.x + innerView.frame.size.width == innerView.contentSize.width)
         {
              outerView.scrollEnabled = NO;
         }
         else
         {
              outerView.scrollEnabled = YES;
         }
    }
}

Answer 3

I have a similar issue. I found the solution, but it works only with innerScrollView.bounces = NO.

@interface PageCtrl ()
    @property (weak, nonatomic) IBOutlet UIScrollView *innerScrollView;
    @property(nonatomic) UIPanGestureRecognizer *panLockScroll;
@end

@implementation PageCtrl
- (void)viewDidLoad {
    // ...
    self.innerScrollView.delegate = self;   

    self.innerScrollView.bounces = NO;   // disable bounces!

    self.panLockScroll = [[UIPanGestureRecognizer alloc]initWithTarget:self action:nil];
    self.panLockScroll.delegate = self;
    [self.innerScrollView addGestureRecognizer:self.panLockScroll];
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer*)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer*)otherGestureRecognizer{
    if( gestureRecognizer == self.panLockScroll && 
        otherGestureRecognizer == self.innerScrollView.panGestureRecognizer ){
        return YES;
    }
    return NO;
}

@end

Answer 4

This works well for me:

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
  outerScrollView.scrollEnabled = NO;
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
  [NSTimer scheduledTimerWithTimeInterval:0.3
                                     target:[NSBlockOperation blockOperationWithBlock:^{ outerScrollView.scrollEnabled = YES; }]
                                   selector:@selector(main)
                                   userInfo:nil
                                    repeats:NO];
}

Remember to adopt the UIScrollViewDelegate in your class declaration and to set the delegate of the innerScrollView to self (do NOT assign the delegate of the outerScrollView)