UIScrollView、PanGestureRecognizer 和 iOs 4答案

【问题标题】：UIScrollView, PanGestureRecognizer and iOs 4UIScrollView、PanGestureRecognizer 和 iOs 4
【发布时间】：2012-01-10 18:16:14
【问题描述】：

我有一个可滚动的视图，我需要在不滚动主视图的情况下触发的手势识别器。

我用过这段代码：

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

但它似乎只适用于 iOS 5。如何在 iOS 4 中使用相同的识别器？

【问题讨论】：

标签： ios ios4 uigesturerecognizer uipangesturerecognizer

【解决方案1】：

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

添加

upRecognizer.delegate = self;

还有这个方法：

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

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

    return NO;
}

【讨论】：

【解决方案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它。

@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

【讨论】：