为什么iOS自动旋转由didReceiveMemoryWarning发布后从Nib加载的视图？ [英] Why Doesn't iOS Autorotate a View loaded from a Nib after it was released by didReceiveMemoryWarning?

问题描述

我的iPad应用程序大量使用自动旋转。这很棒。但是，我注意到如果隐藏视图是由 didReceiveMemoryWarning 的默认实现释放的（如所述这里，当从笔尖重新加载视图时我碰巧在风景中，它以纵向加载它。这会对界面造成严重破坏，直到我手动旋转iPad并强制它进入正确的方向。

My iPad app makes heavy use of autorotation. This is great. However, I've noticed that if a hidden view is released by the default implementation of didReceiveMemoryWarning (as described here), when the view is re-loaded from the nib and I happen to be in landscape, it loads it in portrait. This wreaks havoc with the interface until I rotate the iPad manually and force it to go to the proper orientation.

我以为iOS会在当前方向加载视图;这就是应用程序启动时的功能。但它没有，不是在被 didReceiveMemoryWarning 卸载之后。为什么不？我怎么能让它做到这一点？

I had assumed that iOS would load the view in the current orientation; that's what it does when the app launches. But it no, not after being unloaded by didReceiveMemoryWarning. Why not? And how can I get it to do that?

推荐答案

答案，感谢dbarker ，是视图控制器的旋转方法，包括 -willRotateToInterfaceOrientation：duration：和 -willAnimateRotationToInterfaceOrientation：duration：，在默认实现 didReceiveMemoryWarning 卸载视图后重新加载视图时不会被调用。我不知道为什么它在应用程序启动时会有所不同，但我确实有一个解决方法

The answer, determined thanks to pointers from dbarker, is that the view controller's rotation methods, including -willRotateToInterfaceOrientation:duration: and -willAnimateRotationToInterfaceOrientation:duration:, will not be called when a view is reloaded after a the default implementation of didReceiveMemoryWarning has unloaded the view. I've no idea why it would be different on app launch, but I do have a workaround

我所做的是设置一个名为<$ c $的布尔值。 c> unloadedByMemoryWarning ，在 didReceiveMemoryWarning 中 YES ，如下所示：

What I did was to set a boolean ivar, named unloadedByMemoryWarning, to YES in didReceiveMemoryWarning, like so:

- (void) didReceiveMemoryWarning {
    unloadedByMemoryWarning = YES;
    [super didReceiveMemoryWarning];
}

然后，在 viewDidLoad ，如果该标志为真，我将其设置为否，然后自己调用旋转方法：

Then, in viewDidLoad, if that flag is true, I set it to NO and then call the rotation methods myself:

if (unloadedByMemoryWarning) {
    unloadedByMemoryWarning = NO;
    [self willRotateToInterfaceOrientation:self.interfaceOrientation duration:0];
    [self willAnimateRotationToInterfaceOrientation:self.interfaceOrientation duration:0];
    [self didRotateFromInterfaceOrientation:self.interfaceOrientation];
}

有点糟透了我必须这样做，但确实有效，现在我不太担心因使用太多内存而被iOS杀死。

Kinda sucks that I have to do this, but it does work, and now I'm less concerned about getting killed by iOS for using too much memory.

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