IOS – Note a problem with invalid gesture after transform change

How does UIPanGestureRecognizer become invalid when a UIView is scaled or enlarged?

Analysis:

• Zooming changes the UIviewtransformattribute
• transformChanges to the viewframe
• transformThe touch control cannot trigger the callback method after the change, so the control is judged not to have been touched.

Solution:

There is an API under UIview that we don’t usually use to determine if a touch point is on a control:

- (BOOL)pointInside:(CGPoint)point withEvent:(nullable UIEvent *)event;   // default returns YES if point is in bounds
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So we can rewrite this method for similar problems:

#pragma  mark - touch
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{
    CGPoint p = [self.superview convertPoint:point fromView:self]; 
    if (CGRectContainsPoint(self.frame, p)) {
        return YES;
    }
    return NO;
}
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