Question

In my app I want to detect when the user lift off his second finger and is holding only one on the screen.

The problem is that my touchesEnded:withEvent: shows [[event allTouches] count] to be 2.

How can I detect which one of the touches remains on the screen?

Thanks.

Answer 1

When touch is made by user touchesBegan method triggers. You can keep the pointer to the first touch appeared. It will not be changed until the touch ends.

EDIT:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    if ([touches count] == 1)
    {
        if (!myTouch) myTouch = [touches anyObject]; //I assume myTouch is set to nil in touchesEnded
    }
    else
    {
        //perform your logic for this case
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    if ( myTouch && [touches containsObject: myTouch]
    {
        //perform your logic
        myTouch = nil;
    }
}

I assume you have a variable UITouch *myTouch in your class that handles touch events.