如何将UIView转换为图像

Question

我想将UIView转换为图片并将其保存在我的应用中。有人可以请告诉我如何截取视图的截图或将其转换为图像，以及将其保存在应用程序（不是相机胶卷）的最佳方法是什么？以下是视图的代码：

var overView   = UIView(frame: CGRectMake(0, 0, self.view.frame.width/1.3, self.view.frame.height/1.3))
overView.center = CGPointMake(CGRectGetMidX(self.view.bounds),
CGRectGetMidY(self.view.bounds)-self.view.frame.height/16);
overView.backgroundColor = UIColor.whiteColor()
self.view.addSubview(overView)
self.view.bringSubviewToFront(overView)

Answer 1

UIView上的扩展应该可以解决问题。

extension UIView {

    // Using a function since `var image` might conflict with an existing variable
    // (like on `UIImageView`)
    func asImage() -> UIImage {
        let renderer = UIGraphicsImageRenderer(bounds: bounds)
        return renderer.image { rendererContext in
            layer.render(in: rendererContext.cgContext)
        }
    }
}

Apple不鼓励使用UIGraphicsBeginImageContext启动iOS 10并引入P3色域。 UIGraphicsBeginImageContext仅为sRGB且仅为32位。他们引入了全新的UIGraphicsImageRenderer API，它是完全色彩管理的，基于块的，具有PDF和图像的子类，并自动管理上下文生命周期。查看WWDC16 session 205了解更多详情（图片渲染始于11:50标记左右）

Edit1：为了确保它适用于每台设备，请使用#available并回退到早期版本的iOS：

extension UIView {

    // Using a function since `var image` might conflict with an existing variable
    // (like on `UIImageView`)
    func asImage() -> UIImage {
        if #available(iOS 10.0, *) {
            let renderer = UIGraphicsImageRenderer(bounds: bounds)
            return renderer.image { rendererContext in
                layer.render(in: rendererContext.cgContext)
            }
        } else {
            UIGraphicsBeginImageContext(self.frame.size)
            self.layer.render(in:UIGraphicsGetCurrentContext()!)
            let image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            return UIImage(cgImage: image!.cgImage!)
        }
    }
}

Answer 2

你可以使用扩展名

extension UIImage {
    convenience init(view: UIView) {
        UIGraphicsBeginImageContext(view.frame.size)
        view.layer.render(in:UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.init(cgImage: image!.cgImage!)
    }
}

这是swift 3/4版本：

extension UIImage {
    convenience init(view: UIView) {
        UIGraphicsBeginImageContext(view.frame.size)
        view.layer.render(in:UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.init(cgImage: image!.cgImage!)
    }
}

Answer 3

通过 drawViewHierarchyInRect：afterScreenUpdates：将您的UIView转换为图像，其比renderInContext

快许多倍

重要提示：请勿从 viewDidLoad或viewWillAppear 调用此函数，请确保在视图完全显示/加载后捕获视图

对象C

     UIGraphicsBeginImageContextWithOptions(myView.bounds.size, myView.opaque, 0.0f);
     [myView drawViewHierarchyInRect:myView.bounds afterScreenUpdates:NO];
     UIImage *snapshotImageFromMyView = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();

     myImageView.image =  snapshotImageFromMyView;

保存已编辑的图像相册

     UIImageWriteToSavedPhotosAlbum(snapshotImageFromMyView, nil,nil, nil);

Swift 3/4

    UIGraphicsBeginImageContextWithOptions(myView.bounds.size, myView.isOpaque, 0.0)
    myView.drawHierarchy(in: myView.bounds, afterScreenUpdates: false)
    let snapshotImageFromMyView = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    print(snapshotImageFromMyView)
    myImageView.image = snapshotImageFromMyView

扩展名为iOS11，swift3 / 4的超级简单泛化

extension UIImage{
    convenience init(view: UIView) {

    UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0.0)
    view.drawHierarchy(in: view.bounds, afterScreenUpdates: false)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    self.init(cgImage: (image?.cgImage)!)

  }
}


Use : 
 //myView is completly loaded/visible , calling this code after only after viewDidAppear is call
 imgVV.image = UIImage.init(view: myView)
 // Simple image object
 let img =  UIImage.init(view: myView)

Answer 4

在iOS 10上：

extension UIImage {
    convenience init(view: UIView) {
        UIGraphicsBeginImageContext(view.frame.size)
        view.layer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.init(cgImage: (image?.cgImage)!)
    }
}

Answer 5

    UIGraphicsBeginImageContext(self.view.bounds.size);        
    self.view.layer.renderInContext(UIGraphicsGetCurrentContext())
    var screenShot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

Answer 6

例如，如果我有一个大小的视图：50 50在100,100。我可以使用以下内容截取屏幕截图：

    UIGraphicsBeginImageContextWithOptions(CGSizeMake(100, 100), false, 0);
    self.view.drawViewHierarchyInRect(CGRectMake(-50,-5-,view.bounds.size.width,view.bounds.size.height), afterScreenUpdates: true)
    var image:UIImage = UIGraphicsGetImageFromCurrentImageContext();

Answer 7

iOS 10和Swift 3的最佳实践

，同时仍支持iOS 9及更早版本

 "myDatabase": {
   "url": "[database url here]",
   "connector": "postgresql"}

我不确定这个问题意味着什么：

  

在应用程序中保存它的最佳方法是什么？（不是相机胶卷）？

Answer 8

在我看来，使用初始化器的方法并不是那么好，因为它创建了两个图像。

我更喜欢这个：

extension UIView {
    var snapshot: UIImage? {
        UIGraphicsBeginImageContext(self.frame.size)
        guard let context = UIGraphicsGetCurrentContext() else {
            return nil
        }
        layer.render(in: context)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }
}

Answer 9

Swift 4.2，iOS 10

ts-ignore

样品

crossersOnCorrectSide

Answer 10

var snapshot = overView.snapshotViewAfterScreenUpdates(false)

或在objective-c

UIView* snapshot = [overView snapshotViewAfterScreenUpdates:NO];

Answer 11

这适用于 Xcode 9 / Swift 3.2 / Swift 4 和 Xcode 8 / Swift 3

 if #available(iOS 10.0, *) {

     // for Xcode 9/Swift 3.2/Swift 4 -Paul Hudson's code
     let renderer = UIGraphicsImageRenderer(size: view!.bounds.size)
     let capturedImage = renderer.image { 
         (ctx) in
         view!.drawHierarchy(in: view!.bounds, afterScreenUpdates: true)
     }
     return capturedImage

 } else {

     // for Xcode 8/Swift 3
     UIGraphicsBeginImageContextWithOptions((view!.bounds.size), view!.isOpaque, 0.0)
     view!.drawHierarchy(in: view!.bounds, afterScreenUpdates: false)
     let capturedImage = UIGraphicsGetImageFromCurrentImageContext()
     UIGraphicsEndImageContext()
     return capturedImage!
 }

以下是如何在函数中使用它：

fileprivate func captureUIImageFromUIView(_ view:UIView?) -> UIImage {

     guard (view != nil) else{

        // if the view is nil (it's happened to me) return an alternative image
        let errorImage = UIImage(named: "Error Image")
        return errorImage
     }

     // if the view is all good then convert the image inside the view to a uiimage
     if #available(iOS 10.0, *) {

         let renderer = UIGraphicsImageRenderer(size: view!.bounds.size)
         let capturedImage = renderer.image { 
             (ctx) in
             view!.drawHierarchy(in: view!.bounds, afterScreenUpdates: true)
         }
         return capturedImage

     } else {

         UIGraphicsBeginImageContextWithOptions((view!.bounds.size), view!.isOpaque, 0.0)
         view!.drawHierarchy(in: view!.bounds, afterScreenUpdates: false)
         let capturedImage = UIGraphicsGetImageFromCurrentImageContext()
         UIGraphicsEndImageContext()
         return capturedImage!
     }
}

以下是如何使用函数返回的图像执行某些操作：

@IBOutlet weak fileprivate var myCustomView: UIView!
var myPic: UIImage?

let myImageView = UIImageView()

@IBAction fileprivate func saveImageButtonTapped(_ sender: UIButton) {

   myPic = captureUIImageFromUIView(myCustomView)

   // display the pic inside a UIImageView
   myImageView.image = myPic!
}

我从Paul Hudson那里得到了 Xcode 9 / Swift 3.2 / Swift 4 的答案convert uiview to uiimage

我在很长一段时间之前从某个地方得到了 Xcode 8 / Swift 3 ，我忘记了：（

Answer 12

您可以使用此扩展程序

轻松使用它

// Take a snapshot from a view (just one view)
let viewSnapshot = myView.snapshot

// Take a screenshot (with every views in screen)
let screenSnapshot = UIApplication.shared.snapshot

// Take a snapshot from UIImage initialization
UIImage(view: self.view)

如果您想使用这些扩展方法/变量，请实现此

1. UIImage扩展程序

   extension UIImage {
       convenience init(view: UIView) {
           if let cgImage = view.snapshot?.cgImage {
               self.init(cgImage: cgImage)
           } else {
               self.init()
           }
       }
   }
   

2. UIView扩展

   extension UIView {
   
       var snapshot: UIImage? {
           UIGraphicsBeginImageContextWithOptions(bounds.size, isOpaque, 0.0)
           if UIGraphicsGetCurrentContext() != nil {
               drawHierarchy(in: bounds, afterScreenUpdates: true)
               let screenshot = UIGraphicsGetImageFromCurrentImageContext()
               UIGraphicsEndImageContext()
               return screenshot
           }
           return nil
       }
   }
   

3. UIApplication extension

   extension UIApplication {
   
       var snapshot: UIImage? {
           return keyWindow?.rootViewController?.view.snapshot
       }
   }
   

Answer 13

或iOS 10+你可以使用新的UIGraphicsImageRenderer +推荐的drawHierarchy，在某些情况下可以比layer.renderInContext快得多

extension UIView {
    func asImage() -> UIImage {
        let renderer = UIGraphicsImageRenderer(size: self.bounds.size)
        return renderer.image { _ in
            self.drawHierarchy(in: CGRect(x: 0, y: 0, width: bounds.size.width, height: bounds.size.height), afterScreenUpdates: false)
        }
    }
}

Answer 14

Swift 3 ：

中的实施

在课堂范围之外添加以下代码。

if(a[4] == '\0')

用法：

extension UIImage {
    convenience init(_ view: UIView) {
        UIGraphicsBeginImageContext(view.frame.size)
        view.layer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.init(cgImage: (image?.cgImage)!)
    }
}

Answer 15

谢谢@Bao Tuan Diep！我想补充一点。

使用代码时：

yourView.layer.render(in:UIGraphicsGetCurrentContext()!)

您必须注意：

 - If you had used `autoLayout` or `Masonry` in `yourView` (that you want to convert) .
 - If you did not add `yourView` to another view which means that `yourView` was not used as a subview but just an object.

然后，您必须使用：

[yourView setNeedsLayout];
[yourView layoutIfNeeded];

在yourView之前更新yourView.layer.render(in:UIGraphicsGetCurrentContext()!)。

否则您可能会得到一个不包含元素的图像对象

Answer 16

Swift 4.2

import Foundation
import UIKit  

extension UIImage {

    convenience init(view: UIView) {

        UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0.0)
        view.drawHierarchy(in: view.bounds, afterScreenUpdates: false)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.init(cgImage: (image?.cgImage)!)

    } 
}

  

使用：

     

let img = UIImage.init（view：self.holderView）

Answer 17

自iOS 10起，带有新UIGraphicsImageRenderer的Initializer：

extension UIImage{
    convenience init(view: UIView) {

    let renderer = UIGraphicsImageRenderer(size: self.bounds.size)
    let canvas = CGRect(x: 0, y: 0, width: bounds.size.width, height: bounds.size.height)
    let image = renderer.image { _ in
        self.drawHierarchy(in: canvas, afterScreenUpdates: false)
    }
    self.init(cgImage: (image?.cgImage)!)
  }
}

Answer 18

和我一起工作很好！

Swift4

 extension UIView {

    func toImage() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.isOpaque, 0.0)
        self.drawHierarchy(in: self.bounds, afterScreenUpdates: false)
        let snapshotImageFromMyView = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return snapshotImageFromMyView!
    }

    }

Answer 19

我实施了@Naveed J.这样的方法，它就像一个魅力。

这是他的扩展：

extension UIView {

    // Using a function since `var image` might conflict with an existing variable
    // (like on `UIImageView`)
    func asImage() -> UIImage {
        let renderer = UIGraphicsImageRenderer(bounds: bounds)
        return renderer.image { rendererContext in
            layer.render(in: rendererContext.cgContext)
        }
    }
}

以下是我实施它的方式。

//create an image from yourView to display
//determine the frame of the view/imageimage
let screen = self.superview!.bounds
let width = screen.width / 4 //make image 1/4 width of screen
let height = width
let frame = CGRect(x: 0, y: 0, width: width, height: height)
let x = (screen.size.width - frame.size.width) * 0.5
let y = (screen.size.height - frame.size.height) * 0.5
let mainFrame = CGRect(x: x, y: y, width: frame.size.width, height: frame.size.height)

let yourView = YourView() //instantiate yourView
yourView.frame = mainFrame //give it the frame
yourView.setNeedsDisplay() //tell it to display (I am not 100% sure this is needed)

let characterViewImage = yourView.asImage()

Answer 20

对于包含模糊子视图的视图（例如 UIVisualEffectView 实例），仅 drawViewHierarchyInRect：afterScreenUpdates 有效。

@ViJay Avhad's answer对于这种情况是正确的。

Answer 21

当视图包含Scene Kit子视图，Metal或Sprite Kit的子视图时，无法使用UIGraphicsImageRenderer。在这种情况下，请使用

let renderer = UIGraphicsImageRenderer(size: view.bounds.size)
let image = renderer.image { ctx in
    view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
}

Answer 22

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