Scrolling with two fingers with a UIScrollView

Question

I have an app where my main view accepts both touchesBegan and touchesMoved, and therefore takes in single finger touches, and drags. I want to im

Answer 1

What I do is have my view controller set up the scroll view:

[scrollView setCanCancelContentTouches:NO];
[scrollView setDelaysContentTouches:NO];

And in my child view I have a timer because two-finger touches usually start out as one finger followed quickly by two fingers.:

- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    // Hand tool or two or more touches means a pan or zoom gesture.
    if ((selectedTool == kHandToolIndex) || (event.allTouches.count > 1)) {
        [[self parentScrollView] setCanCancelContentTouches:YES];
        [firstTouchTimer invalidate];
        firstTouchTimer = nil;
        return;
    }

    // Use a timer to delay first touch because two-finger touches usually start with one touch followed by a second touch.
    [[self parentScrollView] setCanCancelContentTouches:NO];
    anchorPoint = [[touches anyObject] locationInView:self];
    firstTouchTimer = [NSTimer scheduledTimerWithTimeInterval:kFirstTouchTimeInterval target:self selector:@selector(firstTouchTimerFired:) userInfo:nil repeats:NO];
    firstTouchTimeStamp = event.timestamp;
}

If a second touchesBegan: event comes in with more than one finger, the scroll view is allowed to cancel touches. So if the user pans using two fingers, this view would get a touchesCanceled: message.