Home » Ios » UIScrollview getting touch events

UIScrollview getting touch events

Posted by: admin November 30, 2017 Leave a comment

Questions:

How can I detect touch points in my UIScrollView? The touches delegate methods are not working.

Answers:

Set up a tap gesture recognizer:

UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(singleTapGestureCaptured:)];
[scrollView addGestureRecognizer:singleTap];    

and you will get the touches in:

- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)gesture
{ 
    CGPoint touchPoint=[gesture locationInView:scrollView];
}

Questions:
Answers:

You can make your own UIScrollview subclass and then you can implement the following:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 

{

NSLog(@"DEBUG: Touches began" );

UITouch *touch = [[event allTouches] anyObject];

    [super touchesBegan:touches withEvent:event];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {

    NSLog(@"DEBUG: Touches cancelled");

    // Will be called if something happens - like the phone rings

    UITouch *touch = [[event allTouches] anyObject];

    [super touchesCancelled:touches withEvent:event];

}


- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

    NSLog(@"DEBUG: Touches moved" );

    UITouch *touch = [[event allTouches] anyObject];

    [super touchesMoved:touches withEvent:event];

}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    NSLog(@"DEBUG: Touches ending" );
    //Get all the touches.
    NSSet *allTouches = [event allTouches];

    //Number of touches on the screen
    switch ([allTouches count])
    {
        case 1:
        {
            //Get the first touch.
            UITouch *touch = [[allTouches allObjects] objectAtIndex:0];

            switch([touch tapCount])
            {
                case 1://Single tap

                    break;
                case 2://Double tap.

                    break;
            }
        }
            break;
    }
    [super touchesEnded:touches withEvent:event];
}

Questions:
Answers:

If we’re talking about the points inside the scrollview then you can hook with the delegate method:

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView

and inside the method, read the property:

@property(nonatomic) CGPoint contentOffset

from the scrollView to get the coordination.