Restrict angle of swipe to scroll UIScrollView

2
votes

I have a vertical scroll view that needs to be scrollable but I want to use the left and right swipe gestures for something else. I have the behavior for each swipe direction working, but I want to restrict the angle of a swipe that scrolls the UIScrollView, so that it has to be really, really vertical, and most left or right leaning swipes activate the other behavior and do not change the scroll position.

I know that I can get the swipe angle by overriding scrollViewDidScroll and comparing the previous and current contentOffset, but I cannot stop the scrollview from scrolling there.

How can I limit the angle of a swipe that scrolls a UIScrollView ?

1
iosobjective-cuiscrollview

1 Answers

0
votes

I think scrollViewDidScroll is too late for what you want to achieve.

Maybe try setting the directionalLockEnabled property of the UIScrollView to YES.(not sure if this helps... but play with it)

And/Or implement the UIScrollViewDelegate method - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView and within this methods implementation grab a pointer to the panGestureRecognizer (readonly) property of the UIScrollView passed in.

From there call translationInView: on the UIPanGestureRecognizer, passing in the view in whose coordinate system the translation of the pan gesture should be computed, and with the CGPoint returned use trigonometry to calculate the angle and if it's not within predetermined limits call setTranslationInView: on the UIPanGestureRecognizer to restore.