iOS - 不支持多次推送相同的视图控制器实例

Question

首先，是的，我知道这是一个常见的问题，已经多次讨论过。虽然我无法解决我的问题，但我想向您展示我的堆栈跟踪，看看是否有人知道这次崩溃的原因是什么。

我在整个应用程序中搜索了对pushViewController的任何调用，在推送viewController之前，我检查它是否已存在：

    if (![navigationController.viewControllers containsObject: channelViewController])
    {
        [navigationController pushViewController: channelViewController animated:NO];
    }

虽然崩溃仍然发生，但这减少了我的用户的崩溃数量。

这是堆栈跟踪：

Fatal Exception: NSInvalidArgumentException
Pushing the same view controller instance more than once is not supported (<ChannelViewController: 0x1b827360>)

Thread : Fatal Exception: NSInvalidArgumentException
0  CoreFoundation                 0x2280010b __exceptionPreprocess
1  libobjc.A.dylib                0x21fa6e17 objc_exception_throw
2  UIKit                          0x269d17e9 -[UINavigationController loadView]
3  UIKit                          0x26cc2271 __54-[UINavigationController pushViewController:animated:]_block_invoke
4  UIKit                          0x269d0e79 -[UINavigationController pushViewController:animated:]
5  UIKit                          0x26a3e979 -[_UIViewControllerTransitionCoordinator _applyBlocks:releaseBlocks:]
6  UIKit                          0x26a6a31d -[_UIViewControllerTransitionContext _runAlongsideCompletions]
7  UIKit                          0x26a690b1 -[_UIViewControllerTransitionContext completeTransition:]
8  UIKit                          0x26a68ed9 -[UITransitionView notifyDidCompleteTransition:]
9  UIKit                          0x26a68a4d -[UITransitionView _didCompleteTransition:]
10 UIKit                          0x26a685ef -[UITransitionView _transitionDidStop:finished:]
11 UIKit                          0x26977605 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:]
12 UIKit                          0x269774ff -[UIViewAnimationState animationDidStop:finished:]
13 QuartzCore                     0x24a3ea21 CA::Layer::run_animation_callbacks(void*)
14 libdispatch.dylib              0x22379b47 _dispatch_client_callout
15 libdispatch.dylib              0x22387ee1 _dispatch_main_queue_callback_4CF$VARIANT$mp
16 CoreFoundation                 0x227c33fd __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__
17 CoreFoundation                 0x227c18f7 __CFRunLoopRun
18 CoreFoundation                 0x22714bf9 CFRunLoopRunSpecific
19 CoreFoundation                 0x227149e5 CFRunLoopRunInMode
20 GraphicsServices               0x23960ac9 GSEventRunModal
21 UIKit                          0x269a4ba1 UIApplicationMain

Answer 1

if (![navigationController.topviewcontroller containsObject: channelViewController])
{
    [navigationController pushViewController: channelViewController.animated:NO];
}

试试这个，它会起作用！你得到的错误只是因为channelViewController已经在导航堆栈中。而且如果你想推动它，只需这样做：

var topview = navigationController.topviewcontroller;
topview.RemoveFromParentViewController();
[navigationController pushViewController: channelViewController animated:NO];