iOS6中的UIPageViewController [英] UIPageViewController in iOS6

问题描述

在iOS6中的方法 viewControllerAfterViewController 和 viewControllerBeforeViewController 如果我返回nil（当我在第一页或最后一页时阻止页面导航）应用程序崩溃例外：

In iOS6 in the methods viewControllerAfterViewController and viewControllerBeforeViewController if I return nil (for block the page navigation when I am in the first or last page) the app crash with this exception:

'提供的视图控制器数量（0）与请求的转换所需的数量（1）不匹配'

'The number of view controllers provided (0) doesn't match the number required (1) for the requested transition'

在iOS5中一切正常。

In iOS5 all works good.

推荐答案

我遇到了同样的问题。我发现原因是在UIPageViewController的UIPanGestureRecognizer上替换了委托，这是一个禁忌。平移手势识别器正在调用一个未记录的方法_gestureRecognizerShouldBegin :(注意前导下划线）UIPageViewController实现并显然依赖于正常工作（读取：not-crash）。我最终在我的类中实现了respondsToSelector：和forwardingTargetForSelector：它使用UIPageViewController将未记录的委托方法传递给UIPageViewController，而没有特别命名它（几乎肯定会让我获得应用商店评论拒绝）。

I had the same issue. I found that the cause was replacing the delegate on the UIPanGestureRecognizer of the UIPageViewController, a no-no really. The pan gesture recognizer was calling an undocumented method _gestureRecognizerShouldBegin: (note the leading underscore) that UIPageViewController implements and apparently relies upon to work properly (read: not-crash). I ended up implementing respondsToSelector: and forwardingTargetForSelector: in my class that uses the UIPageViewController to pass the undocumented delegate method on to the UIPageViewController without specifically naming it (and almost certainly earning me an app store review rejection).

-(BOOL)respondsToSelector:(SEL)aSelector {
    if ([super respondsToSelector:aSelector])
        return YES;
    else if ([self.pageViewController respondsToSelector:aSelector])
        return YES;
    else
        return NO;
}

- (id)forwardingTargetForSelector:(SEL)aSelector {
    if ([super respondsToSelector:aSelector]) {
        return nil;
    } else if ([self.pageViewController respondsToSelector:aSelector]) {
        return self.pageViewController;
    }
    return nil;
}

我的长期解决方案是重新使用UIPageViewController，这样我就不会不需要取代手势识别器代表。

My longer term solution will be to rework the use of UIPageViewController such that I don't need to displace the gesture recognizer delegates.

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