Question

Im having a little problem on handling touches in my apps.

I set my touchesBegan like this:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *currentTouch = [[event allTouches] anyObject];
    touchPoint = [currentTouch locationInView:self.view];
    if (CGRectContainsPoint(image1.frame, touchPoint)) {
        image1IsTouched = YES;
    }
}

Then i set my touch move like this:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{  
    UITouch *currentTouch = [[event allTouches] anyObject];
    currentPoint = [currentTouch locationInView:currentTouch.view];

    if(image1IsTouched == YES) {
        image1.center = CGPointMake(currentPoint.x,currentPoint.y);
        .....
    }
}

Now i tried my app on actual unit and thats where i notice my problem. While im touching the image1 with 1 finger the app is doing ok and its checking for collision everytime i drag my finger. The problem occurs when i touch the screen with another finger while touching/dragging the image. The image im currently touching will jump to the other finger. I’ve tried [myView setMultipleTouchEnable:NO]; & using NSArray on touches and comparing the [touches count] with the touch but its not working. Can someone show me how to set a uiimageview to act on single touch only. Thanks.

Answer 1

First, you should use UITouch *currentTouch = [touches anyObject]; to get the current touch.

Second, you should check that touches.count == 1 to make sure there’s only one finger on the screen, and ignore touch input if there’s more than one, unless you wanted to support multitouch.