如果你想让屏幕宽度/高度与设备方向无关(只适用于从横向方向启动的视图控制器的纵向大小):

CGFloat screenWidthInPoints = [UIScreen mainScreen].nativeBounds.size.width/[UIScreen mainScreen].nativeScale;
CGFloat screenHeightInPoints = [UIScreen mainScreen].nativeBounds.size.height/[UIScreen mainScreen].nativeScale;

[UIScreen mainScreen]。物理屏幕的边界矩形，以像素为单位。这个矩形是基于设备的肖像向上方向。该值不会随着设备的旋转而改变。

在iOS中如何获得屏幕的尺寸?

你所发布的代码的问题是，你指望视图的大小与屏幕的大小相匹配，正如你所看到的，情况并不总是这样。如果你需要屏幕大小，你应该查看代表屏幕本身的对象，如下所示:

CGRect screenRect = [[UIScreen mainScreen] bounds];
CGFloat screenWidth = screenRect.size.width;
CGFloat screenHeight = screenRect.size.height;

拆分视图更新:在评论中，Dmitry问道:

如何在分屏视图中获取屏幕的大小?

上面给出的代码报告屏幕的大小，即使在分屏模式下也是如此。当你使用分屏模式时，应用程序的窗口会发生变化。如果上面的代码没有提供您所期望的信息，那么就像OP一样，您找错对象了。在这种情况下，你应该看着窗口而不是屏幕，就像这样:

CGRect windowRect = self.view.window.frame;
CGFloat windowWidth = windowRect.size.width;
CGFloat windowHeight = windowRect.size.height;

斯威夫特4.2

let screenRect = UIScreen.main.bounds
let screenWidth = screenRect.size.width
let screenHeight = screenRect.size.height

// split screen            
let windowRect = self.view.window?.frame
let windowWidth = windowRect?.size.width
let windowHeight = windowRect?.size.height

我已经把上面的一些Objective-C答案翻译成Swift代码。每一篇译文都引用了原文的答案。

主要解决途径

let screen = UIScreen.main.bounds
let screenWidth = screen.size.width
let screenHeight = screen.size.height

##简单函数回答

func windowHeight() -> CGFloat {
    return UIScreen.main.bounds.size.height
}

func windowWidth() -> CGFloat {
    return UIScreen.main.bounds.size.width
}

##设备朝向回答

let screenHeight: CGFloat
let statusBarOrientation = UIApplication.shared.statusBarOrientation
// it is important to do this after presentModalViewController:animated:
if (statusBarOrientation != .portrait
    && statusBarOrientation != .portraitUpsideDown) {
    screenHeight = UIScreen.main.bounds.size.width
} else {
    screenHeight = UIScreen.main.bounds.size.height
}

# #日志回答

let screenWidth = UIScreen.main.bounds.size.width
let screenHeight = UIScreen.main.bounds.size.height
println("width: \(screenWidth)")
println("height: \(screenHeight)")

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

斯威夫特3.0

的宽度

UIScreen.main.bounds.size.width

身高

UIScreen.main.bounds.size.height

iOS 13+的答案(找到键窗口的代码来源):

guard let window = UIApplication.shared.windows.first(where: { $0.isKeyWindow }) else {
    return
}

let windowWidth = window.frame.width
let windowHeight = window.frame.height