Max/Min Scale of Pinch Zoom in UIPinchGestureRecognizer - iPhone iOS

Question

How would I be able to limit the scale of the UIPinchGestureRecognizer to a min and max level? The scale property below seems to be relative to the last known scale (the de

Answer 1

Other approaches mentioned here did not work for me, but taking a couple things from previous answers and (in my opinion) simplifying things, I've got this to work for me. effectiveScale is an ivar set to 1.0 in viewDidLoad.

-(void)zoomScale:(UIPinchGestureRecognizer *)recognizer
{
    if([recognizer state] == UIGestureRecognizerStateEnded) {
        // Reset last scale
        lastScale = 1.0;
        return;
    }

    if ([recognizer state] == UIGestureRecognizerStateBegan ||
    [recognizer state] == UIGestureRecognizerStateChanged) {

        CGFloat pinchscale = [recognizer scale];
        CGFloat scaleDiff = pinchscale - lastScale;

        if (scaleDiff < 0)
            scaleDiff *= 2; // speed up zoom-out
        else
            scaleDiff *= 0.7; // slow down zoom-in

        effectiveScale += scaleDiff;
        // Limit scale between 1 and 2
        effectiveScale = effectiveScale < 1 ? 1 : effectiveScale;
        effectiveScale = effectiveScale > 2 ? 2 : effectiveScale;

        // Handle transform in separate method using new effectiveScale    
        [self makeAndApplyAffineTransform];
        lastScale = pinchscale;
    }
}