限制添加到 UIPanGestureRecognizer 的视图在其超级视图中的移动

Question

我想知道是否有一种方法可以在使用 GestureRecognizer 时将 UIView 的移动限制在其超级视图中。

例如。我有一个 UIImageview ，我向其添加带有操作 panPiece 的 UIPanGestureRecognizer 。我通过以下方式调整它的中心，以避免它移动出它的超级视图。但它不能正常工作。

-(CGPoint) centerWithBounds:(CGPoint)center andViewFrame:(CGRect)viewFrame andBoundingFrame:(CGRect)boundingFrame{

 CGFloat lowerXBound  = boundingFrame.origin.x + ( viewFrame.size.width/2 );
 CGFloat higherXBound = boundingFrame.origin.x + boundingFrame.size.width - ( viewFrame.size.width/2 );

 CGFloat lowerYBound  = boundingFrame.origin.y + ( viewFrame.size.height/2 );
 CGFloat higherYBound = boundingFrame.origin.y + boundingFrame.size.height - ( viewFrame.size.height/2 );

 if ( center.x < lowerXBound) {
  center.x = lowerXBound;
 }
 if ( center.x > higherXBound ){
  center.x = higherXBound;
 }
 if ( center.y < lowerYBound) {
  center.y = lowerYBound;
 }
 if ( center.y > higherYBound ){
  center.y = higherYBound;
 }

 return center;
}

- (void)panPiece:(UIPanGestureRecognizer *)gestureRecognizer
{
    UIView *piece = [gestureRecognizer view];

    [self adjustAnchorPointForGestureRecognizer:gestureRecognizer];

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
        CGPoint translation = [gestureRecognizer translationInView:[piece superview]];
        CGPoint translatedCenter = CGPointMake([piece center].x + translation.x, [piece center].y + translation.y);
  CGPoint center = [self centerWithBounds:translatedCenter andViewFrame:[piece frame] andBoundingFrame:[[piece superview] frame]];
        [piece setCenter:center];
        [gestureRecognizer setTranslation:CGPointZero inView:[piece superview]];
    }
}

感谢代码帮助。

Answer 1

您只需要使用超级视图的属性clipsToBounds（将其设置为YES）即可。之前也有同样的问题。之后就可以完美工作了。

Answer 2

或许是因为

标准 UIImageView，尽管是 UIView 子类，但不会对添加到其中的手势识别器做出反应

使用uigesturerecognizers