对 <UINavigationController: 0xa98e050> 的开始/结束外观

问题描述

在编译我得到的代码时

对 <UINavigationController: 0xa98e050> 的开始/结束外观转换的不平衡调用"

"Unbalanced calls to begin/end appearance transitions for <UINavigationController: 0xa98e050>"

警告.

这是我的代码

KVPasscodeViewController *passcodeController = [[KVPasscodeViewController alloc] init];
passcodeController.delegate = self;

UINavigationController *passcodeNavigationController = [[UINavigationController alloc] initWithRootViewController:passcodeController];
[(UIViewController *)self.delegate presentModalViewController:passcodeNavigationController animated:YES];

推荐答案

我知道这是一个老问题，但是为了那些再次遇到这个问题的人，这里是我发现的.

I know this is an old question, but for the sake of those who run across this again, here is what I've found.

首先，问题没有说明新 viewController 的调用位置.
我怀疑这是从 -(void)viewDidLoad

Firstly, The question does not state where the new viewController was being called.
I suspect this was called from -(void)viewDidLoad

将适当的代码移动到 -(void)viewDidAppear: 并且问题应该会消失.

Move the appropriate code to -(void)viewDidAppear: and the problem should go away.

这是因为在 -viewDidLoad 处，视图已加载，但尚未呈现，动画和视图尚未完成.

This is because at -viewDidLoad, the view has loaded, but has not yet been presented and the animations and views have not completed.

如果您的意图是推动窗口，请在窗口呈现并绘制后执行.

If your intent is to push a window, do it after the window has been presented and has painted.

如果您发现自己使用计时器来控制系统行为，请问问自己做错了什么，或者如何才能更正确地做到这一点.

If you ever find yourself using timers to control system behavior, ask yourself what you are doing wrong, or how you could do it more properly.

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