Question

I noticed an strange issue with my application that only occurs on the iPhone 3G and iPhone 3GS. I am creating a scroll view with two pages. On the second page of the scroll, when you try to scroll the picker, it is very unresponsive. It kinda appears that my application can’t distinguish between the scrolling of the picker and the scrolling of the scrollview, because sometimes you scroll up and it goes to the left.

Please keep in mind, this works great on the iPhone 4 and iPhone 4S.

Has anyone ran into this problem before or any idea of what is actually going on?

Answer 1

Apparently the UIScrollView and UIPickerView cause problems if used together. However, this only occurred on the iPhone 3 and iPhone 3GS.

The solution was to subclass UIScrollView and implement the following method.

- (UIView *)hitTest:(CGPoint)point 
         withEvent:(UIEvent *)event
{
    UIView *result = [super hitTest:point withEvent:event];

    if ([result.superview isKindOfClass:[UIPickerView class]]) {
        self.canCancelContentTouches = NO;  
        self.delaysContentTouches = NO;
    }
    else {
        self.canCancelContentTouches = YES;
        self.delaysContentTouches = YES;
    }
    return result;
}