touchesMoved no longer triggers after changing UIView to UIScrollView?

Question

I had a UIView with lots of objects. I also had an implementation of touchesMoved like this:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"move");
}

I recently wanted the view to scroll, so I simply opened up the UIView, and in Interface Builder changed its object class to UIScrollView. However, now the 'touchesMoved' method is never called even when I touch the screen.

Can someone please help me get touchesMoved working again? I'm not sure what I did to break it!

EDIT: I tried following this guide but I might've done something wrong. From reading other posts it seems like UIScrollView can't accept touch events itself, and they need to be sent up the responder chain? I will be extremely grateful for anyone who can help guide me through this problem... my app was just about ready for submission when I realized the UIScrolView killed my touch detection! (I just changed my apps UIView to UIScrollView to allow compatibility with iPhone 4).

Answer 1

I just took a look at the guide in your edit, and I think I can see the problem. See this answer on a similar question.

Your UIScrollView subclass will look something like this:

#import "AppScrollView.h"

@implementation AppScrollView

- (id)initWithFrame:(CGRect)frame
{
    return [super initWithFrame:frame];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"AppScrollView touchesEnded:withEvent:");

    // If not dragging, send event to next responder
    if (!self.dragging)
        [[self.nextResponder nextResponder] touchesEnded:touches withEvent:event];
    else
        [super touchesEnded: touches withEvent: event];

}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"AppScrollView touchesMoved:withEvent:");

    [[self.nextResponder nextResponder] touchesMoved:touches withEvent:event];
}

@end

And your class that includes the AppScrollView object should adopt the UIScrollViewDelegate protocol and implement these methods:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"SomeClass touchesMoved:withEvent:");
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"SomeClass touchesEnded:withEvent:");
}

Then the logged output will look like this:

2013-06-11 10:45:21.625 Test[54090:c07] AppScrollView touchesMoved:withEvent:
2013-06-11 10:45:21.625 Test[54090:c07] SomeClass touchesMoved:withEvent:
2013-06-11 10:45:21.642 Test[54090:c07] AppScrollView touchesMoved:withEvent:
2013-06-11 10:45:21.642 Test[54090:c07] SomeClass touchesMoved:withEvent:
2013-06-11 10:45:21.655 Test[54090:c07] AppScrollView touchesEnded:withEvent:
2013-06-11 10:45:21.656 Test[54090:c07] SomeClass touchesEnded:withEvent: