UIScrollView只用一根手指滚动 [英] UIScrollView scrolling only with one finger
问题描述
iOS7& iOS8
iOS7 & iOS8
我需要在 UIScrollview 中禁用2或3个手指滚动。
I need to disable 2 or three fingers scrolling in UIScrollview.
我试过：
[self.scrollView.panGestureRecognizer setMaximumNumberOfTouches:1];
[self.scrollView.panGestureRecognizer setMinimumNumberOfTouches:1];
但它没有效果。仍然可以用2个手指滚动。
But it has no effect. It is still possible to scroll with 2 fingers.
如果我试图将最大值和最小值设置为2.禁用一个手指滚动，但可以滚动3个手指:(
If i tried to set max and min to 2. One finger scrolling was disabled but 3 fingers scrolling possible :(
我也试过了，但没有成功：
I tried this too, but without success:
for (UIGestureRecognizer* pan in self.scrollView.gestureRecognizers) {
OTTNSLog(@"touches: %ld", (unsigned long)pan.numberOfTouches);
if ([pan isKindOfClass:[UIPanGestureRecognizer class]])
{
UIPanGestureRecognizer *mpanGR = (UIPanGestureRecognizer *) pan;
mpanGR.minimumNumberOfTouches = 1;
mpanGR.maximumNumberOfTouches = 1;
}
if ([pan isKindOfClass:[UISwipeGestureRecognizer class]])
{
UISwipeGestureRecognizer *mswipeGR = (UISwipeGestureRecognizer *) pan;
mswipeGR.numberOfTouchesRequired = 1;
}
}
有谁知道，怎么解决这个问题？
Does anybody know, how it solve this ?
谢谢。
推荐答案
问题：
PROBLEM:
当 UIPanGestureRecognizer 时是 UIScrollView 的基础 - 遗憾的是它也会影响 UIPageViewController - maximumNumberOfTouches 的行为不符合预期， minimumNumberOfTouches 但是总是正确地限制下端。
When the UIPanGestureRecognizer is underlying a UIScrollView - which unfortunately does also effect UIPageViewController - the maximumNumberOfTouches is not behaving as expected, the minimumNumberOfTouches however always limits the lower end correctly.
监控这些参数时，他们会报告回来正确的价值 - 他们似乎做他们的工作 - 只是 UIScrollView 本身不尊重他们并忽略他们的设置！
When monitoring these parameters they report back correct values - they seem to do their job - it's just that UIScrollView itself doesn't honor them and ignores their settings!
解决方案：
SOLUTION:
设置 minimumNumberOfTouches 到所需的值，例如1 - 非常重要的是 - maximumNumberOfTouches 到2 !!!
Set the minimumNumberOfTouches to the desired value e.g. 1 and - very importantly - the maximumNumberOfTouches to 2 !!!
myScrollView.panGestureRecognizer.minimumNumberOfTouches = 1;
myScrollView.panGestureRecognizer.maximumNumberOfTouches = 2;
符合 UIGestureRecognizerDelegate 协议。您不必为 UIScrollView 设置 panGestureRecognizer.delegate ！委托已经设置，因为 UIScrollView 需要成为其自己的 pan / pinchGestureRecognizer 的委托。
Conform to the UIGestureRecognizerDelegate protocol in your scrollView's @interface declaration. You don't have to set the panGestureRecognizer.delegate for a UIScrollView!!! The delegate is already set because UIScrollView requires to be the delegate of its own pan/pinchGestureRecognizer.
然后实施 UIGestureRecognizer 委托方法：
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
NSLog(@"%d", gestureRecognizer.numberOfTouches);
NSLog(@"%@", gestureRecognizer.description);
if (gestureRecognizer == self.panGestureRecognizer) {
if (gestureRecognizer.numberOfTouches > 1) {
return NO;
} else {
return YES;
}
} else {
return YES;
}
}
}
一个更安全的版本：
AN EVEN SAFER VERSION:
如果你有一个自定义的scrollView类并想要开启非常安全的一面，你还可以添加一行代码来消除其他scrollViews的歧义：
If you have a custom scrollView class and wanna be on the VERY safe side you can also add one more line of code to disambiguate against other scrollViews:
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
NSLog(@"%d", gestureRecognizer.numberOfTouches);
NSLog(@"%@", gestureRecognizer.description);
if ([gestureRecognizer.view isMemberOfClass:[MY_CustomcrollView class]]) {
if (gestureRecognizer == self.panGestureRecognizer) {
if (gestureRecognizer.numberOfTouches > 1) {
return NO;
} else {
return YES;
}
} else {
return YES;
}
} else {
return YES;
}
}
其他信息：
ADDITIONAL INFORMATION:
NSLog 会告诉您触摸次数。如果您将 min 和 max 设置为相同的值（如上例中的1） if-loop 永远不会被触发...; - ）
The NSLogs tell you the number of touches. If you set both the min and max to the same value (like 1 in the example above) the if-loop would never be triggered... ;-)
这就是为什么 maximumNumberOfTouches 必须至少 minimumNumberOfTouches + 1
That is why maximumNumberOfTouches has to be at least minimumNumberOfTouches + 1
panGestureRecognizer.minimumNumberOfTouches = 1;
panGestureRecognizer.maximumNumberOfTouches = minimumNumberOfTouches + 1;
GEEK SECTION：
GEEK SECTION:
for (UIView *view in self.view.subviews) {
if ([view isKindOfClass:[UIScrollView class]]) {
NSLog(@"myPageViewController - SCROLLVIEW GESTURE RECOGNIZERS: %@", view.gestureRecognizers.description);
((UIPanGestureRecognizer *)view.gestureRecognizers[1]).minimumNumberOfTouches = 1;
((UIPanGestureRecognizer *)view.gestureRecognizers[1]).maximumNumberOfTouches = 2;
}
}
这是访问底层scrollView的方法负责分页 UIPageViewController 。将此代码放入例如 viewDidLoad： c $ c> UIPageViewController （self）。
This is the way to access the underlying scrollView that is responsible for the paging of a UIPageViewController. Put this code in the e.g. viewDidLoad: of the UIPageViewController (self).
如果您根本无法访问scrollView - 例如 UIPageViewController 在动态 UITableViewCell 中，创建和单元重用在运行时发生，并且不能在其contentView上设置出口 - 在 UIScrollView上放置一个类别并覆盖那里的委托方法。不过要小心！这会影响应用程序中的每个scrollView - 所以请执行正确的内省（类检查），就像我上面的'EVEN SAFER'示例...; - ）
If you don't have access to the scrollView at all - like for a UIPageViewController in a dynamic UITableViewCell where creation and cell reuse happens at runtime and no outlets can be set on its contentViews - put a category on UIScrollView and override the delegate method there. But be careful! This effects every scrollView in your application - so do proper introspection (class-checking) like in my 'EVEN SAFER' example above... ;-)
SIDENOTE：
SIDENOTE:
不幸的是，同样的技巧不适用于 pinchGestureRecognizer UIScrollView 因为它没有公开 min / maxNumberOfTouches 属性。在监控时，它总是报告2次触摸（你显然需要捏） - 所以它的内部 min / maxNumberOfTouches 似乎已被设置为2 - 即使 UIScrollView 也没有遵守自己的设置，并且乐意与之保持愉快任意数量的手指（超过2个）。所以没有办法限制捏到有限数量的手指......
Unfortunately the same trick doesn't work with the pinchGestureRecognizer on UIScrollView because it doesn't expose a min/maxNumberOfTouches property. When monitored it always reports 2 touches (which you obviously need to pinch) - so its internal min/maxNumberOfTouches seem to have been set both to 2 - even if UIScrollView isn't honoring its own settings and keeps happily pinching with any numbers of fingers (more than 2). So there is no way to restrict pinching to a limited amount of fingers...
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