How to interact with a horizontal scrollview that is a subview of a scroll view?

Question

I have a horizontal scroll view that is a subview of a vertical scroll view. It looks like the vertical scroll view is intercepting all user interactions. I want to be able to scroll horizontally the horizontal scroll view. How would I do this?

Here is a short snippet of my code:

  UIScrollView *scrollView2 = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0,     self.view.width, 100)];

  scrollView2.contentSize = CGSizeMake(self.view.bounds.size.width + 400, 100);

  _scrollView.contentSize = CGSizeMake(self.view.width, 400);

  _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.height - 108)];

[self.view addSubview:_scrollView];

[_scrollView addSubview:scrollView2];

Answer 1

You can subclass the parent scrollview and override touchesShouldCancelInContentView: to return NO whenever the view is child scroll view. ie;

MyScrollView.h

@interface MyScrollView: UIScrollView
@end

and in MyScrollView.m

@implementation MyScrollView


-(BOOL)touchesShouldCancelInContentView:(UIView *)touchedView{
      if(touchedView == _scrollView2){ //Get the reference of that child scroll view here
         return NO;
      }else{
         [super touchesShouldCancelInContentView:touchedView];
      }
}

Then your posted code should look like:

UIScrollView *scrollView2 = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0,     self.view.width, 100)];

  scrollView2.contentSize = CGSizeMake(self.view.bounds.size.width + 400, 100);



  _myScrollView = [[MyScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.height - 108)];
  _myScrollView.contentSize = CGSizeMake(self.view.width, 400);


[_myScrollView addSubview:scrollView2];
[self.view addSubview:_myScrollView];

Answer 2

Unable to comment. Hence answering here.

I faced this problem earlier. I do not remember the exact solution. But I think the problem was that you are trying to add the second view controller after the second. I think you should try the reverse.

[_scrollView addSubview:scrollView2];
[self.view addSubview:_scrollView];