Ios 切换PopViewController激活时的EXC_错误访问：

对于控制器之间的日志导航，我使用-popViewControllersAnimated:方法的滑动。有时它会导致EXC\u坏访问的奇怪崩溃。原因可能是什么

- (void)sw_popViewControllerAnimated:(BOOL)animated {

//1. get top controller before pop
//2. pop
//3. get top controller after pop
//4. log it
NSString *controllerFromIdentifier = @"";
__block NSString *controllerToIdentifier = @"";

    NSDictionary *controllerFromAdditionalParams = @{};

    UIViewController *topController = ((UINavigationController*)self).topViewController;

    [self sw_popViewControllerAnimated:animated];

    UIViewController *topControllerAfterPop = ((UINavigationController*)self).topViewController;

}

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在topController上尝试不安全的。这可能会有帮助。