Transfer touches from uiview to uiscrollview - ios

Question

I have a UIScrollview (With image) in UIView (Red color).
UIView - {0,0, 320, 236} UIScrollview - {0, 8, 300, 220}
In my uiview, I got touches.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{}
I need to transfer touch from UIView to UIScrollview. (e.g if user swipe from right side of uiview to left, uiscrollview should scroll to left in sync with user touch). May I know how to do?

Answer 1

The idea is to get a reference to your scrollView inside your UIView, calculate the x touches delta and adjust the contentOffset property of the scrollView accordingly.
So, in your UIView class:
#implementation MyView{
CGPoint _startPosition;
CGPoint _previousPosition;
}
Initialize the above variables in your
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
_startPosition = [touch locationInView:self];
_previousPosition = _startPosition;
}
Then in your touchesMoved:
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
CGPoint currentPosition = [touch locationInView:self.scrollView];
if(!CGPointEqualToPoint(_previousPosition, _startPosition)){
CGFloat deltaX = _previousPosition.x-currentPosition.x;
[UIView animateWithDuration:0.1 animations:^{
//
self.scrollView.contentOffset = CGPointMake(self.scrollView.contentOffset.x +
deltaX, self.scrollView.contentOffset.y);
}];
}
_previousPosition = currentPosition;
}
The scrollView.contentOffset is adjusted in an animation block to make the scroll smooth.
Link to a working project: https://github.com/sliaquat/stack_overlfow_answer_28036976