ViewWillDisappear导航/标签控制器的值为nil

Question

我需要重新配置UINavigationController我的内部大小UITabController.这在视图加载时工作正常viewWillAppear().但是,当我尝试调整大小时viewWillDisappear,我得到Nav/Tab控制器的nil值.例:

override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)
    self.navigationController?.hidesBarsOnSwipe = false //po self.navigationController --> nil
    ...
    var smallerFrame: CGRect = (self.tabBarController?.view.frame)!; //po self.tabBarController --> nil
    ...
}

我不确定发生了什么.为什么会发生这种情况viewWillDisappear但不会发生viewWillAppear？

Answer 1

我有同样的问题.结束了在viewDidLoad中为导航控制器设置弱属性.

@property(weak, nonatomic) UINavigationController *weakNavigationController;