在viewDidLoad中，视图为null [英] View is null in viewDidLoad

问题描述

我创建了UITabBarController，每个选项卡包含UINavigationController，并在此UINavigationController中设置了rootviewcontroller，所有这些操作均在界面生成器中完成.在viewDidLoad中，我尝试从视图中获取帧大小，但是当我引用视图时，它返回null.以前有没有人经历过.

I created UITabBarController with each tab contain UINavigationController and set rootviewcontroller in this UINavigationController, all of this is done in interface builder. In viewDidLoad I try to get frame size from view, but when I reference view it return null. Have anyone experienced this before.

所有IBoutlet均已正确连接.

All IBoutlet are properly connected.

推荐答案

viewDidLoad如果在您的.xib中连接了视图，则返回nil视图可能意味着:

viewDidLoad returning a nil view if the view is connected in your .xib could mean:

对于程序初始化(自定义控制器):

For programmatic initialisation (custom controllers):

• 您忘记总共在视图控制器类上调用initWithNibName:bundle:(您可能已经调用了init或其他名称).
• 您已经在视图控制器类中覆盖了loadView方法，但是它没有设置view.

• You forgot to call initWithNibName:bundle: on the view controller class altogether (you may have called init or something instead).
• You've overridden the loadView method in your view controller class, but it doesn't set the view.

对于所有控制器:

• 未正确建立插座连接.
• 在显示视图或视图控制器之前，您不小心将其释放了.
• 初始化视图时，未正确指定nibName参数(找不到笔尖或找到了一个没有视图的笔尖.尽管这也会引发异常).
• 没有足够的内存来分配view(尽管该应用可能到那时将被终止).

• An outlet connection hasn't been made correctly.
• You have accidentally released the view or view controller before showing it.
• The nibName parameter was not properly specified when initialising the view (the nib could not be found or one without a view was found.. though this should also throw an exception).
• There wasn't enough memory to allocate the view (the app would likely have been terminated by that point though).

我建议您改为尝试在viewWillAppear:中进行帧大小计算，然后查看view在那时是否仍为nil.

I'd recommend you try doing frame size calculations in viewWillAppear: instead and see if the view is still nil at that point.

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