UIScrollView、PanGestureRecognizer 和 iOs 4

Question

我有一个可滚动视图，我需要手势识别器，该手势识别器将在不滚动主视图的情况下触发。

我使用过这段代码：

UISwipeGestureRecognizer *upRecognizer = 
    [[UISwipeGestureRecognizer alloc] initWithTarget:self 
                                              action:@selector(upSwipeHandle:)];
upRecognizer.direction = UISwipeGestureRecognizerDirectionUp;
[upRecognizer setNumberOfTouchesRequired:2];
[controller.view addGestureRecognizer:upRecognizer];
[[controller.scrollView panGestureRecognizer]
    requireGestureRecognizerToFail:upRecognizer];

但它似乎只在 iOS 5 中工作。我如何在 iOS 4 中使用相同的识别器？

Answer 1

我通过使用 UIGestureRecognizer 委托方法解决了我的问题。

只需添加

upRecognizer.delegate = self;

这个方法：

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{

    if ([gestureRecognizer isKindOfClass:[UISwipeGestureRecognizer class]] && [otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        return YES;
    }

    return NO;
}  

Answer 2

我遇到了同样的问题。我在 4.3 模拟器中运行了类似的代码，但该代码失败了，因为 scrollView.panGestureRecognizer 仅在 iOS 5.0+ 中可用。

我通过向 UIScrollView 添加一个类别来解决这个问题。

@interface UIScrollView(panGestureRecognizer)
@end
@implementation UIScrollView(panGestureRecognizer)
// iOS5 has a panGestureRecognizer property
// Add a getter for iOS 4.3+
- (UIPanGestureRecognizer *)panGestureRecognizer
{
    for (UIGestureRecognizer *gestureRecognizer in self.gestureRecognizers)
    {
        if ([gestureRecognizer isKindOfClass: [UIPanGestureRecognizer class]]) {
            return (UIPanGestureRecognizer *)gestureRecognizer;
        }
    }
    return nil;
}
@end