Question

我的手势识别代码在iOS 4.2中运行良好，但在iOS 4.3中它不起作用。我无法在iOS 4.2到4.3中找到手势识别器的任何记录更改，但我已在iPad和模拟器中确认我的代码不再有效。

这就是我在做的事情：

在我的视图控制器的ViewDidLoad方法中，我把：

UISwipeGestureRecognizer *swipeUpGesture = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipedScreenLeft:)] autorelease];
swipeUpGesture.numberOfTouchesRequired = 2;
swipeUpGesture.direction = (UISwipeGestureRecognizerDirectionLeft);
[scrollView addGestureRecognizer:swipeUpGesture];

在iOS 4.2中，这可以按预期工作，但在iOS 4.3中，即使用两根手指轻扫，也不会调用swipedScreenLeft。一切都编译并运行，没有任何错误或警告。

是否有任何可能阻止此手势识别器在iOS 4.3中工作的内容，即使它在iOS 4.2中正常工作？

另外我注意到在iOS 4.2下，如果我用两根手指触摸屏幕但没有做出正确的手势，没有任何事情会发生，但在iOS 4.3中，如果我用两根手指触摸屏幕，它就好像我只是用一根手指触摸。就好像iOS 4.3无法识别我的应用程序中的多点触控事件。

另一个注意事项：我的tapGestureRecognizer在iOS 4.3中运行良好，只是swipeGestureRecognizer没有。

Answer 1

问题出在UIScrollView上，我也对此表示愤怒：http://i.stack.imgur.com/dqx3d.png

[更新1]这里的解决方案：

情况：UIViewController的视图将UIScrollView作为子视图（禁用滚动视图分页）。

我用来附加UIView手势的代码：

UISwipeGestureRecognizer *swipeLeftRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipedScreenLeft:)];
[swipeLeftRecognizer setNumberOfTouchesRequired:2.0f];
swipeLeftRecognizer.delegate = self;
[swipeLeftRecognizer setDirection:UISwipeGestureRecognizerDirectionLeft];

[self.view addGestureRecognizer:swipeLeftRecognizer];

[swipeLeftRecognizer release];

要启用iOS 4.3，我只需将UIViewController添加为UIGestureRecognizerDelegate

然后，我使用以下委托方法拦截并允许使用视图的滑动同时识别scrollView的panGesture。代码如下：

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

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

    return NO;

}

[更新2]

要用两根手指禁用UIScrollView平移，我认为您必须制作滚动视图，UISCrollView类的自定义子类并更改panGesture检测器的某些行为，但我没有尝试这样做。相反，我选择了一个更懒惰的解决方案，基本上我根据UISwipeGestureRecognizer的当前状态启用/禁用scrollView滚动功能。此外，为了防止在另一个方向上的双重触摸移动，我为此目的附加了另一个识别器。

您必须为滑动探测器创建两个属性。

@property (nonatomic,assign) UISwipeGestureRecognizer *swipeRightRecognizer;
@property (nonatomic,assign) UISwipeGestureRecognizer *swipeLeftRecognizer;

然后我这样编码：

[self setSwipeRightRecognizer:[[UISwipeGestureRecognizer alloc] initWithTarget:nil action:nil]];
[swipeRightRecognizer setNumberOfTouchesRequired:2.0f];
swipeRightRecognizer.delegate = self;
[swipeRightRecognizer setDirection:UISwipeGestureRecognizerDirectionRight];
[self addObserver:self forKeyPath:@"swipeRightRecognizer.state" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];
[self.view addGestureRecognizer:swipeRightRecognizer];
[swipeRightRecognizer release];

[self setSwipeLeftRecognizer:[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipedScreenLeft:)]];
[swipeLeftRecognizer setNumberOfTouchesRequired:2.0f];
swipeLeftRecognizer.delegate = self;
[swipeLeftRecognizer setDirection:UISwipeGestureRecognizerDirectionLeft];
[self addObserver:self forKeyPath:@"swipeLeftRecognizer.state" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];
[self.view addGestureRecognizer:swipeLeftRecognizer];
[swipeLeftRecognizer release];

然后添加此方法：

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

    if (self.swipeRightRecognizer.state == UIGestureRecognizerStateFailed) {
        self.scrollView.scrollEnabled = YES;
        return;
    }

    if ([self.swipeRightRecognizer numberOfTouches] != 2.0f) {
        self.scrollView.scrollEnabled = YES;   
    }
    else{
        self.scrollView.scrollEnabled = NO;   
    }
}

并更新我在之前的“[更新]”中发布的现有方法：

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

    if ([gestureRecognizer isKindOfClass:[UISwipeGestureRecognizer class]] && [otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        if ([gestureRecognizer numberOfTouches] != 2.0f) {
            self.scrollView.scrollEnabled = YES;   
        }
        else{
            self.scrollView.scrollEnabled = NO;   
        }

        return YES;
    }
    return NO;
}

最后，删除dealloc中的观察者：

[self removeObserver:self forKeyPath:@"swipeRightRecognizer.state"];
[self removeObserver:self forKeyPath:@"swipeLeftRecognizer.state"];

我打赌有一个更清洁的解决方案，但它确实有效..

希望它有所帮助;）

Answer 2

如果您使用UIImageView并且想要对其进行双击，则应启用用户交互。我浪费了很多时间来发现这一点。

Answer 3

也许我的代码可以帮助您解决问题。我已经在iOS 4.3的iPad上测试了代码而且效果很好

UISwipeGestureRecognizer *oSwipeLeft = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(mPreviousPage:) ] autorelease];
oSwipeLeft.numberOfTouchesRequired = 2;
oSwipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
[self.view addGestureRecognizer:oSwipeLeft];

UISwipeGestureRecognizer *oSwipeRight = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(mNextPage:) ] autorelease];
oSwipeRight.numberOfTouchesRequired = 2;
oSwipeRight.direction = UISwipeGestureRecognizerDirectionRight;
[self.view addGestureRecognizer:oSwipeRight];

UISwipeGestureRecognizer *oSwipeUp = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(mPreviousPage:) ] autorelease];
oSwipeUp.numberOfTouchesRequired = 2;
oSwipeUp.direction = UISwipeGestureRecognizerDirectionUp;
[self.view addGestureRecognizer:oSwipeUp];

手势识别器在iOS 4.3中停止工作

3 个答案: