Question

I have a (vertical) UISlider inside a UIScrollview. I’d like to be able to change the value of the slider, and, without lifting my finger, scroll the scrollview left or right.

Desired behavior:

Touch down inside vertical UISlider, followed by a finger drag left or right causes the scrollview to scroll

Actual behavior:

Touch down inside vertical UISlider, followed by a finger drag left or right causes no movement in UIScrollview. A touch down outside the UISlider followed by a drag will scroll the scrollview as expected

UIView has a property called exclusiveTouch which seems as if it might be related to my problem. I tried setting it to NO, with no luck.

So, how can is set up my UISliders so that the scrollview beneath them will respond to touches which originate inside the UISliders?

Answer 1

Have you tried subclassing UIScrollView and implementing - (BOOL)touchesShouldCancelInContentView:(UIView *)view? According to the Apple documentation:

// called before scrolling begins if touches have already been delivered to a subview of the scroll view. if it returns NO the touches will continue to be delivered to the subview and scrolling will not occur
// not called if canCancelContentTouches is NO. default returns YES if view isn't a UIControl

If you simply return NO if the view is your UISlider, this may do what you want, assuming your UIScrollView only scrolls horizontally. If this doesn’t work, you likely will have to do custom touch handling (ie. overriding touchesBegan:withEvent:, touchesChanged:withEvent:, etc.) for both your UIScrollView and your UISlider.