我们还必须考虑设备的朝向:

CGFloat screenHeight;
// it is important to do this after presentModalViewController:animated:
if ([[UIApplication sharedApplication] statusBarOrientation] == UIDeviceOrientationPortrait || [[UIApplication sharedApplication] statusBarOrientation] == UIDeviceOrientationPortraitUpsideDown){
    screenHeight = [UIScreen mainScreen].applicationFrame.size.height;
}
else{
    screenHeight = [UIScreen mainScreen].applicationFrame.size.width;
}

现代的答案是:

如果你的应用在iPad上支持分屏视图，这个问题就变得有点复杂了。你需要窗口的大小，而不是屏幕的大小，这可能包含2个应用程序。窗口的大小也可能在运行时发生变化。

使用应用程序主窗口的大小:

UIApplication.shared.delegate?.window??.bounds.size ?? .zero

注意:上述方法在启动时可能会在窗口成为关键窗口之前得到错误的值。如果你只需要宽度，非常推荐以下方法:

UIApplication.shared.statusBarFrame.width

使用uisscreen .main.bounds的旧解决方案将返回设备的边界。如果你的应用程序运行在分屏视图模式，它会得到错误的尺寸。

当应用程序包含2个或2个以上的窗口且窗口大小较小时，最热答案中的Self.view.window可能会显示错误的大小。

我们还必须考虑设备的朝向:

CGFloat screenHeight;
// it is important to do this after presentModalViewController:animated:
if ([[UIApplication sharedApplication] statusBarOrientation] == UIDeviceOrientationPortrait || [[UIApplication sharedApplication] statusBarOrientation] == UIDeviceOrientationPortraitUpsideDown){
    screenHeight = [UIScreen mainScreen].applicationFrame.size.height;
}
else{
    screenHeight = [UIScreen mainScreen].applicationFrame.size.width;
}

CGFloat宽度= [[UIScreen mainScreen] bounds].size.width; CGFloat height = [[UIScreen mainScreen]bounds].size.height;

我以前用过这些方便的方法:

- (CGRect)getScreenFrameForCurrentOrientation {
    return [self getScreenFrameForOrientation:[UIApplication sharedApplication].statusBarOrientation];
}

- (CGRect)getScreenFrameForOrientation:(UIInterfaceOrientation)orientation {

    CGRect fullScreenRect = [[UIScreen mainScreen] bounds];

    // implicitly in Portrait orientation.
    if (UIInterfaceOrientationIsLandscape(orientation)) {
      CGRect temp = CGRectZero;
      temp.size.width = fullScreenRect.size.height;
      temp.size.height = fullScreenRect.size.width;
      fullScreenRect = temp;
    }

    if (![[UIApplication sharedApplication] statusBarHidden]) {
      CGFloat statusBarHeight = 20; // Needs a better solution, FYI statusBarFrame reports wrong in some cases..
      fullScreenRect.size.height -= statusBarHeight;
    }

    return fullScreenRect;
} 

NSLog(@"%.0f", [[UIScreen mainScreen] bounds].size.width);
NSLog(@"%.0f", [[UIScreen mainScreen] bounds].size.height);