横向打开应用时，新创建的 UIWindow 是横向的答案

【问题标题】：Newly created UIWindow is sideways when app is opened on landscape横向打开应用时，新创建的 UIWindow 是横向的
【发布时间】：2019-09-13 20:49:02
【问题描述】：

我有一个 iPad 应用程序，我在该应用程序的开头创建了一个新的UIWindow，并在我进行一些资源同步时显示它。当 iPad 处于纵向时启动应用程序时，一切都很好。然而，在横向时，新创建的UIWindow's 大小看起来不错，但它看起来是横向的，而且它的坐标看起来很奇怪。以下是纵向和横向的屏幕截图：

风景一是向右旋转一次得到的。

我创建并显示UIWindow 的代码如下：

UIWindow *window=[UIApplication sharedApplication].keyWindow;
self.progressWindow = [[UIWindow alloc] initWithFrame:window.frame];
self.progressWindow.backgroundColor = [UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.5f];
self.progressWindow.windowLevel = UIWindowLevelAlert;

/* some other code to create the subviews */

[self.progressWindow makeKeyAndVisible];

此问题仅在 iOS 8 上出现。

【问题讨论】：

标签： ios ipad uiwindow

【解决方案1】：

据我了解，新创建的 UIWindow 在方向改变时不会自动旋转。我不知道这对 iOS 8 来说是新的还是一个错误，但我能够通过以下代码克服这个问题：

UIWindow *window=[UIApplication sharedApplication].keyWindow;
self.progressWindow = [[UIWindow alloc] initWithFrame:window.frame];
self.progressWindow.backgroundColor = [UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.5f];
self.progressWindow.windowLevel = UIWindowLevelAlert;

/* some other code to create the subviews */

[self handleOrientationChange];
[self.progressWindow makeKeyAndVisible];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleOrientationChange) name:UIApplicationDidChangeStatusBarFrameNotification object:nil];

handleOrientationChange的实现如下：

#define DegreesToRadians(degrees) (degrees * M_PI / 180)

- (void)handleOrientationChange
{
    if (self.progressWindow)
    {
        // rotate the UIWindow manually
        UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
        [self.progressWindow setTransform:[self transformForOrientation:orientation]];

        // resize the UIWindow according to the new screen size
        if ([[UIScreen mainScreen] respondsToSelector:@selector(nativeBounds)])
        {
            // iOS 8
            CGRect screenRect = [UIScreen mainScreen].nativeBounds;
            CGRect progressWindowFrame = self.progressWindow.frame;
            progressWindowFrame.origin.x = 0;
            progressWindowFrame.origin.y = 0;
            progressWindowFrame.size.width = screenRect.size.width / [UIScreen mainScreen].nativeScale;
            progressWindowFrame.size.height = screenRect.size.height / [UIScreen mainScreen].nativeScale;
            self.progressWindow.frame = progressWindowFrame;
        }
        else
        {
            // iOs 7 or below
            CGRect screenRect = [UIScreen mainScreen].bounds;
            CGRect progressWindowFrame = self.progressWindow.frame;
            progressWindowFrame.origin.x = 0;
            progressWindowFrame.origin.y = 0;
            progressWindowFrame.size.width = screenRect.size.width;
            progressWindowFrame.size.height = screenRect.size.height;
            self.progressWindow.frame = progressWindowFrame;
        }
    }
}

- (CGAffineTransform)transformForOrientation:(UIInterfaceOrientation)orientation {

    switch (orientation) {

        case UIInterfaceOrientationLandscapeLeft:
            return CGAffineTransformMakeRotation(-DegreesToRadians(90));

        case UIInterfaceOrientationLandscapeRight:
            return CGAffineTransformMakeRotation(DegreesToRadians(90));

        case UIInterfaceOrientationPortraitUpsideDown:
            return CGAffineTransformMakeRotation(DegreesToRadians(180));

        case UIInterfaceOrientationPortrait:
        default:
            return CGAffineTransformMakeRotation(DegreesToRadians(0));
    }
}

我从this问题的接受答案中得到了这个想法。

【讨论】：

【解决方案2】：

共享应用程序通过它的 key- 窗口属性：

let w = UIApplication.sharedApplication().keyWindow

然而，那个参考，稍微不稳定，因为系统可以创建临时窗口并将它们设置为应用程序的关键窗口。

试试吧

[[UIApplication sharedApplication].delegate window]

【讨论】：

我只是使用 keyWindow 来获取它的框架，所以我认为这不是问题。