超越 UIView 的交互

问题描述

当 UIButton 的框架位于其父框架之外时，UIButton(或任何其他控件)是否有可能接收触摸事件?因为当我尝试这个时，我的 UIButton 似乎无法接收任何事件.我该如何解决这个问题?

Is it possible for a UIButton (or any other control for that matter) to receive touch events when the UIButton's frame lies outside of it's parent's frame? Cause when I try this, my UIButton doesn't seem to be able to receive any events. How do I work around this?

推荐答案

是的.您可以覆盖 hitTest:withEvent: 方法以返回一个视图，该视图包含比该视图包含的更大的点集.请参阅 UIView 类参考.

Yes. You can override the hitTest:withEvent: method to return a view for a larger set of points than that view contains. See the UIView Class Reference.

示例:

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    CGFloat radius = 100.0;
    CGRect frame = CGRectMake(-radius, -radius,
                              self.frame.size.width + radius,
                              self.frame.size.height + radius);

    if (CGRectContainsPoint(frame, point)) {
        return self;
    }
    return nil;
}

(澄清后:)为了确保按钮被视为在父级范围内，您需要覆盖 pointInside:withEvent: in父级包含按钮的框架.

Edit 2: (After clarification:) In order to ensure that the button is treated as being within the parent's bounds, you need to override pointInside:withEvent: in the parent to include the button's frame.

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
    if (CGRectContainsPoint(self.view.bounds, point) ||
        CGRectContainsPoint(button.view.frame, point))
    {
        return YES;
    }
    return NO;
}

注意上面用于覆盖 pointInside 的代码并不完全正确.正如 Summon 在下面解释的那样，请执行以下操作:

Note the code just there for overriding pointInside is not quite correct. As Summon explains below, do this:

-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
    {
    if ( CGRectContainsPoint(self.oversizeButton.frame, point) )
        return YES;

    return [super pointInside:point withEvent:event];
    }

请注意，您很可能会使用 self.oversizeButton 作为此 UIView 子类中的 IBOutlet；然后您可以将有问题的超大按钮"拖动到有问题的特殊视图.(或者，如果由于某种原因你在一个项目中经常这样做，你会有一个特殊的 UIButton 子类，你可以查看这些类的子视图列表.)希望它有所帮助.

Note that you'd very likely do it with self.oversizeButton as an IBOutlet in this UIView subclass; then you can just drag the "oversize button" in question, to, the special view in question. (Or, if for some reason you were doing this a lot in a project, you'd have a special UIButton subclass, and you could look through your subview list for those classes.) Hope it helps.

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