我找到了这段代码：
func screenShotMethod() {
//Create the UIImage
UIGraphicsBeginImageContext(view.frame.size)
view.layer.renderInContext(UIGraphicsGetCurrentContext())
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
//Save it to the camera roll
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)
}
我需要做什么才能将其他元素（例如导航栏）也显示在截图中？
不要只简单地给出答案，让我解释一下你当前的代码是如何工作的，以及如何修改它来捕获整个屏幕。
UIGraphicsBeginImageContext(view.frame.size)
这行代码创建一个与view大小相同的新图像上下文。重要的是要记住，新的图像上下文与view大小相同。除非你想捕捉低分辨率（非Retina）版本的应用程序，否则你可能应该使用UIGraphicsBeginImageContextWithOptions，然后可以传递0.0以获得与设备主屏幕相同的比例因子。
view.layer.renderInContext(UIGraphicsGetCurrentContext())
这行代码会将视图层呈现到当前的图形上下文中（也就是您刚刚创建的上下文）。在这里需要注意的主要事项是，只有view（及其子视图）被绘制到图像上下文中。
let image = UIGraphicsGetImageFromCurrentImageContext()
这行代码从图形上下文中绘制的内容创建一个UIImage对象。
UIGraphicsEndImageContext()
view相同大小的图像，其中包含了view及其子视图绘制的内容。UIWindow是UIView的子类，因此它也可以被绘制到图像上下文中。UIGraphicsBeginImageContext 的文档，您将看到它调用 UIGraphicsBeginImageContextWithOptions 并使用比例因子为 1.0。阅读 其 文档将告诉您，您可以将比例因子设置为 0.0 以与您的主屏幕相同。 - David RönnqvistSwift 4
/// Takes the screenshot of the screen and returns the corresponding image
///
/// - Parameter shouldSave: Boolean flag asking if the image needs to be saved to user's photo library. Default set to 'true'
/// - Returns: (Optional)image captured as a screenshot
open func takeScreenshot(_ shouldSave: Bool = true) -> UIImage? {
var screenshotImage :UIImage?
let layer = UIApplication.shared.keyWindow!.layer
let scale = UIScreen.main.scale
UIGraphicsBeginImageContextWithOptions(layer.frame.size, false, scale);
guard let context = UIGraphicsGetCurrentContext() else {return nil}
layer.render(in:context)
screenshotImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
if let image = screenshotImage, shouldSave {
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)
}
return screenshotImage
}
已更新至Swift 2
您提供的代码有效，但无法捕获屏幕截图中的NavigationBar和StatusBar。如果您想要截取包含NavigationBar的设备屏幕截图，则必须使用以下代码：
func screenShotMethod() {
let layer = UIApplication.sharedApplication().keyWindow!.layer
let scale = UIScreen.mainScreen().scale
UIGraphicsBeginImageContextWithOptions(layer.frame.size, false, scale);
layer.renderInContext(UIGraphicsGetCurrentContext()!)
let screenshot = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
UIImageWriteToSavedPhotosAlbum(screenshot, nil, nil, nil)
}
使用这段代码：
StatusBar 在最终图像中不会出现。已在iOS上测试：9、10、11、12、13
import UIKit
extension UIApplication {
func getKeyWindow() -> UIWindow? {
if #available(iOS 13, *) {
return windows.first { $0.isKeyWindow }
} else {
return keyWindow
}
}
func makeSnapshot() -> UIImage? { return getKeyWindow()?.layer.makeSnapshot() }
}
extension CALayer {
func makeSnapshot() -> UIImage? {
let scale = UIScreen.main.scale
UIGraphicsBeginImageContextWithOptions(frame.size, false, scale)
defer { UIGraphicsEndImageContext() }
guard let context = UIGraphicsGetCurrentContext() else { return nil }
render(in: context)
let screenshot = UIGraphicsGetImageFromCurrentImageContext()
return screenshot
}
}
extension UIView {
func makeSnapshot() -> UIImage? {
if #available(iOS 10.0, *) {
let renderer = UIGraphicsImageRenderer(size: frame.size)
return renderer.image { _ in drawHierarchy(in: bounds, afterScreenUpdates: true) }
} else {
return layer.makeSnapshot()
}
}
}
extension UIImage {
convenience init?(snapshotOf view: UIView) {
guard let image = view.makeSnapshot(), let cgImage = image.cgImage else { return nil }
self.init(cgImage: cgImage, scale: image.scale, orientation: image.imageOrientation)
}
}
imageView.image = UIApplication.shared.makeSnapshot()
// or
imageView.image = view.makeSnapshot()
// or
imageView.image = view.layer.makeSnapshot()
// or
imageView.image = UIImage(snapshotOf: view)
Xcode 8.2.1，Swift 3
import UIKit
extension UIApplication {
var screenShot: UIImage? {
if let layer = keyWindow?.layer {
let scale = UIScreen.main.scale
UIGraphicsBeginImageContextWithOptions(layer.frame.size, false, scale);
if let context = UIGraphicsGetCurrentContext() {
layer.render(in: context)
let screenshot = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return screenshot
}
}
return nil
}
}
如果您尝试在iOS 9x中使用版本1代码，将会出现错误：CGImageCreateWithImageProvider: invalid image provider: NULL。
import UIKit
extension UIApplication {
var screenShot: UIImage? {
if let rootViewController = keyWindow?.rootViewController {
let scale = UIScreen.main.scale
let bounds = rootViewController.view.bounds
UIGraphicsBeginImageContextWithOptions(bounds.size, false, scale);
if let _ = UIGraphicsGetCurrentContext() {
rootViewController.view.drawHierarchy(in: bounds, afterScreenUpdates: true)
let screenshot = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return screenshot
}
}
return nil
}
}
let screenShot = UIApplication.shared.screenShot!
Swift UIImage 扩展：
extension UIImage {
convenience init?(view: UIView?) {
guard let view: UIView = view else { return nil }
UIGraphicsBeginImageContextWithOptions(view.bounds.size, false, UIScreen.main.scale)
guard let context: CGContext = UIGraphicsGetCurrentContext() else {
UIGraphicsEndImageContext()
return nil
}
view.layer.render(in: context)
let contextImage: UIImage? = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
guard
let image: UIImage = contextImage,
let pngData: Data = image.pngData()
else { return nil }
self.init(data: pngData)
}
}
使用方法：
let myImage: UIImage? = UIImage(view: myView)
为了方便起见，我会在它自己的文件中添加一个扩展名。
import UIKit
public extension UIWindow {
func capture() -> UIImage {
UIGraphicsBeginImageContextWithOptions(self.frame.size, self.opaque, UIScreen.mainScreen().scale)
self.layer.renderInContext(UIGraphicsGetCurrentContext()!)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}
按照以下方式调用扩展...
let window: UIWindow! = UIApplication.sharedApplication().keyWindow
let windowImage = window.capture()
同样地，可以扩展UIView以捕获该视图的图像....
在iOS 10中创建上下文的推荐方式是使用UIGraphicsImageRenderer。
extension UIView {
func capture() -> UIImage? {
var image: UIImage?
if #available(iOS 10.0, *) {
let format = UIGraphicsImageRendererFormat()
format.opaque = isOpaque
let renderer = UIGraphicsImageRenderer(size: frame.size, format: format)
image = renderer.image { context in
drawHierarchy(in: frame, afterScreenUpdates: true)
}
} else {
UIGraphicsBeginImageContextWithOptions(frame.size, isOpaque, UIScreen.main.scale)
drawHierarchy(in: frame, afterScreenUpdates: true)
image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
}
return image
}
}
Swift 5
在新设备（如 iPhone 12 Pro）上不会崩溃的情况下，捕捉整个屏幕（除状态栏外）。
extension UIApplication {
func getScreenshot() -> UIImage? {
guard let window = keyWindow else { return nil }
let bounds = UIScreen.main.bounds
UIGraphicsBeginImageContextWithOptions(bounds.size, false, 0)
window.drawHierarchy(in: bounds, afterScreenUpdates: true)
guard let image = UIGraphicsGetImageFromCurrentImageContext() else { return nil }
UIGraphicsEndImageContext()
return image
}
}
以前使用UIApplication.shared.keyWindow?.layer.render(in: context)的解决方案会在某些设备上（如 iPhone 12 Pro）导致内存崩溃。
支持 Swift 5 和 iOS 13
对于任何想要快速获取视图截图并返回UIImage的函数的人：
func getScreenshot() -> UIImage? {
//creates new image context with same size as view
// UIGraphicsBeginImageContextWithOptions (scale=0.0) for high res capture
UIGraphicsBeginImageContextWithOptions(view.frame.size, true, 0.0)
// renders the view's layer into the current graphics context
if let context = UIGraphicsGetCurrentContext() { view.layer.render(in: context) }
// creates UIImage from what was drawn into graphics context
let screenshot: UIImage? = UIGraphicsGetImageFromCurrentImageContext()
// clean up newly created context and return screenshot
UIGraphicsEndImageContext()
return screenshot
}
func captureScreen() -> UIImage {
var window: UIWindow? = UIApplication.sharedApplication().keyWindow
window = UIApplication.sharedApplication().windows[0] as? UIWindow
UIGraphicsBeginImageContextWithOptions(window!.frame.size, window!.opaque, 0.0)
window!.layer.renderInContext(UIGraphicsGetCurrentContext())
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image;
}
Swift 5
如果您只需要屏幕的真实快照（包括键盘和状态栏）：
let snap = UIScreen.main.snapshotView(afterScreenUpdates: false)
snap 是一个 UIView，其框架自动设置为屏幕的边界。将其添加到视图控制器的视图中，现在会给你一个看起来像被冻结的 UI：
view.addSubview(snap)
场景更新
iOS应用程序现在采用了场景，这使得上述解决方案无效。您必须快照活动场景的主窗口，而不是快照主屏幕。
如果您的应用程序只有一个场景，则以下内容将起作用。但是，如果您有多个场景，则必须先找到活动场景（然后找到其主窗口）。
if let sceneDelegate = UIApplication.shared.connectedScenes.first?.delegate as? SceneDelegate,
let snap = sceneDelegate.window?.snapshotView(afterScreenUpdates: false) {
view.addSubview(snap)
}
对于有多个场景的应用程序：https://dev59.com/9FMI5IYBdhLWcg3wRZbJ#69780721