如何截取 UIView 的屏幕快照？

我想知道我的 iPhone 应用程序如何能够采取一个特定的 UIView作为一个 UIImage的屏幕截图。

我试过这个代码，但我得到的是一个空白的图像。

UIGraphicsBeginImageContext(CGSizeMake(320,480));
CGContextRef context = UIGraphicsGetCurrentContext();
[myUIView.layer drawInContext:context];
UIImage *screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

myUIView有320x480的尺寸，它有一些子视图。 做这件事的正确方法是什么？

105233 次浏览
小开 
CGImageRef UIGetScreenImage();

苹果现在允许我们在公共应用程序中使用它，即使它是一个私有 API

小开
最佳答案

我认为你可能想要 renderInContext，而不是 drawInContext.draInContext 是更多的一个方法，你会覆盖..。

请注意，它可能不工作在所有的视图，特别是一年左右以前，当我试图使用这与现场摄像机视图它没有工作。

小开 
- (void)drawRect:(CGRect)rect {
UIGraphicsBeginImageContext(self.bounds.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
}

此方法可以放入 Controller 类中。

小开

苹果不允许:

CGImageRef UIGetScreenImage();

应用程序应使用 drawRect方法截图，如下所示: Http://developer.apple.com/library/ios/#qa/qa2010/qa1703.html

小开

您需要捕获 钥匙窗口作为截图或 UIView。您可以在 视网膜解决方案中使用 UIGraphicsBeginImageContextWithOptions 并设置其比例参数0.0 f。它总是以本地分辨率捕捉(iPhone4和更高版本的 retina)。

这一个做一个全屏幕截图(关键窗口)

UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
CGRect rect = [keyWindow bounds];
UIGraphicsBeginImageContextWithOptions(rect.size,YES,0.0f);
CGContextRef context = UIGraphicsGetCurrentContext();
[keyWindow.layer renderInContext:context];
UIImage *capturedScreen = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

此代码以本机分辨率捕获 UIView

CGRect rect = [captureView bounds];
UIGraphicsBeginImageContextWithOptions(rect.size,YES,0.0f);
CGContextRef context = UIGraphicsGetCurrentContext();
[captureView.layer renderInContext:context];
UIImage *capturedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

如果需要的话，这样可以在应用程序的文档文件夹中以95% 的质量保存 jpg 格式的 UIImage。

NSString  *imagePath = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/capturedImage.jpg"]];
[UIImageJPEGRepresentation(capturedImage, 0.95) writeToFile:imagePath atomically:YES];
小开

IOS7有一个新的方法，允许您在当前图形上下文中绘制视图层次结构。这可以用来快速获得 UIImage。

我在 UIView上实现了一个分类方法，以获得作为 UIImage的视图:

- (UIImage *)pb_takeSnapshot {
UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);


[self drawViewHierarchyInRect:self.bounds afterScreenUpdates:YES];


// old style [self.layer renderInContext:UIGraphicsGetCurrentContext()];


UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}

它比现有的 renderInContext:方法快得多。

参考资料: https://developer.apple.com/library/content/qa/qa1817/_index.html

更新为 SWIFT : 做同样事情的扩展:

extension UIView {


func pb_takeSnapshot() -> UIImage {
UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.mainScreen().scale)


drawViewHierarchyInRect(self.bounds, afterScreenUpdates: true)


// old style: layer.renderInContext(UIGraphicsGetCurrentContext())


let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}

更新 SWIFT 3

    UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.main.scale)


drawHierarchy(in: self.bounds, afterScreenUpdates: true)


let image = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return image
小开

从 iOS7开始，我们有以下默认方法:

- (UIView *)snapshotViewAfterScreenUpdates:(BOOL)afterUpdates

调用上面的方法比自己将当前视图的内容呈现到位图图像中要快。

如果要将图形效果(如模糊)应用于快照，请改用 drawViewHierarchyInRect:afterScreenUpdates:方法。

Https://developer.apple.com/library/ios/documentation/uikit/reference/uiview_class/uiview/uiview.html

小开 
-(UIImage *)convertViewToImage
{
UIGraphicsBeginImageContext(self.bounds.size);
[self drawViewHierarchyInRect:self.bounds afterScreenUpdates:YES];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();


return image;
}
小开

下面的代码片段用于截屏:

UIGraphicsBeginImageContext(self.muUIView.bounds.size);


[myUIView.layer renderInContext:UIGraphicsGetCurrentContext()];


UIImage *screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

使用 renderInContext:方法代替 drawInContext:方法

renderInContext:方法将接收方及其子层呈现到当前上下文中 直接从图层树呈现。

小开

我已经为 UIView 创建了一个可用的扩展，可以在 Swift 中截屏:

extension UIView{


var screenshot: UIImage{


UIGraphicsBeginImageContext(self.bounds.size);
let context = UIGraphicsGetCurrentContext();
self.layer.renderInContext(context)
let screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenShot
}
}

要使用它，只需输入:

let screenshot = view.screenshot
小开

我从 UIView 创建了这个 保存屏幕快照的扩展

extension UIView {
func saveImageFromView(path path:String) {
UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.mainScreen().scale)
drawViewHierarchyInRect(bounds, afterScreenUpdates: true)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
UIImageJPEGRepresentation(image, 0.4)?.writeToFile(path, atomically: true)


}}

致电 :

let pathDocuments = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true).first!
let pathImage = "\(pathDocuments)/\(user!.usuarioID.integerValue).jpg"
reportView.saveImageFromView(path: pathImage)

如果要创建 png，必须更改:

UIImageJPEGRepresentation(image, 0.4)?.writeToFile(path, atomically: true)

作者

UIImagePNGRepresentation(image)?.writeToFile(path, atomically: true)
小开

您可以使用以下 UIView 类别-

@implementation UIView (SnapShot)


- (UIImage *)snapshotImage
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);
[self drawViewHierarchyInRect:self.bounds afterScreenUpdates:NO];
// old style [self.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
@end
小开

细节

  • Xcode Version 10.3(10G8) ，Swift 5

解决方案

import UIKit


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()
}
}
}

用法

let image = view.makeSnapshot()

完整样本

不要忘记 在这里添加解决方案代码

import UIKit


class ViewController: UIViewController {


@IBOutlet var viewForScreenShot: UIView!
@IBOutlet var screenShotRenderer: UIImageView!


@IBAction func makeViewScreenShotButtonTapped2(_ sender: UIButton) {
screenShotRenderer.image = viewForScreenShot.makeSnapshot()
}
}

主线，故事板

<?xml version="1.0" encoding="UTF-8"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="11762" systemVersion="16C67" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
<device id="retina4_7" orientation="portrait">
<adaptation id="fullscreen"/>
</device>
<dependencies>
<deployment identifier="iOS"/>
<plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="11757"/>
<capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
</dependencies>
<scenes>
<!--View Controller-->
<scene sceneID="tne-QT-ifu">
<objects>
<viewController id="BYZ-38-t0r" customClass="ViewController" customModule="stackoverflow_2214957" customModuleProvider="target" sceneMemberID="viewController">
<layoutGuides>
<viewControllerLayoutGuide type="top" id="y3c-jy-aDJ"/>
<viewControllerLayoutGuide type="bottom" id="wfy-db-euE"/>
</layoutGuides>
<view key="view" contentMode="scaleToFill" id="8bC-Xf-vdC">
<rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
<autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
<subviews>
<view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="Acg-GO-mMN">
<rect key="frame" x="67" y="28" width="240" height="128"/>
<subviews>
<textField opaque="NO" clipsSubviews="YES" contentMode="scaleToFill" contentHorizontalAlignment="left" contentVerticalAlignment="center" borderStyle="roundedRect" textAlignment="natural" minimumFontSize="17" translatesAutoresizingMaskIntoConstraints="NO" id="4Fr-O3-56t">
<rect key="frame" x="72" y="49" width="96" height="30"/>
<constraints>
<constraint firstAttribute="height" constant="30" id="cLv-es-h7Q"/>
<constraint firstAttribute="width" constant="96" id="ytF-FH-gdm"/>
</constraints>
<nil key="textColor"/>
<fontDescription key="fontDescription" type="system" pointSize="14"/>
<textInputTraits key="textInputTraits"/>
</textField>
</subviews>
<color key="backgroundColor" red="0.0" green="0.47843137250000001" blue="1" alpha="0.49277611300000002" colorSpace="custom" customColorSpace="sRGB"/>
<color key="tintColor" white="0.66666666666666663" alpha="1" colorSpace="calibratedWhite"/>
<constraints>
<constraint firstItem="4Fr-O3-56t" firstAttribute="centerX" secondItem="Acg-GO-mMN" secondAttribute="centerX" id="egj-rT-Gz5"/>
<constraint firstItem="4Fr-O3-56t" firstAttribute="centerY" secondItem="Acg-GO-mMN" secondAttribute="centerY" id="ymi-Ll-WIV"/>
</constraints>
</view>
<button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="SQq-IE-pvj">
<rect key="frame" x="109" y="214" width="157" height="30"/>
<state key="normal" title="make view screen shot"/>
<connections>
<action selector="makeViewScreenShotButtonTapped2:" destination="BYZ-38-t0r" eventType="touchUpInside" id="KSY-ec-uvA"/>
</connections>
</button>
<imageView userInteractionEnabled="NO" contentMode="scaleAspectFit" horizontalHuggingPriority="251" verticalHuggingPriority="251" translatesAutoresizingMaskIntoConstraints="NO" id="CEZ-Ju-Tpq">
<rect key="frame" x="67" y="269" width="240" height="128"/>
<constraints>
<constraint firstAttribute="width" constant="240" id="STo-iJ-rM4"/>
<constraint firstAttribute="height" constant="128" id="tfi-zF-zdn"/>
</constraints>
</imageView>
</subviews>
<color key="backgroundColor" red="0.95941069162436543" green="0.95941069162436543" blue="0.95941069162436543" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
<constraints>
<constraint firstItem="CEZ-Ju-Tpq" firstAttribute="top" secondItem="SQq-IE-pvj" secondAttribute="bottom" constant="25" id="6x1-iB-gKF"/>
<constraint firstItem="Acg-GO-mMN" firstAttribute="leading" secondItem="CEZ-Ju-Tpq" secondAttribute="leading" id="LUp-Be-FiC"/>
<constraint firstItem="SQq-IE-pvj" firstAttribute="top" secondItem="Acg-GO-mMN" secondAttribute="bottom" constant="58" id="Qu0-YT-k9O"/>
<constraint firstItem="Acg-GO-mMN" firstAttribute="centerX" secondItem="8bC-Xf-vdC" secondAttribute="centerX" id="Qze-zd-ajY"/>
<constraint firstItem="Acg-GO-mMN" firstAttribute="trailing" secondItem="CEZ-Ju-Tpq" secondAttribute="trailing" id="b1d-sp-GHD"/>
<constraint firstItem="SQq-IE-pvj" firstAttribute="centerX" secondItem="CEZ-Ju-Tpq" secondAttribute="centerX" id="qCL-AF-Cro"/>
<constraint firstItem="Acg-GO-mMN" firstAttribute="top" secondItem="y3c-jy-aDJ" secondAttribute="bottom" constant="8" symbolic="YES" id="u5Y-eh-oSG"/>
<constraint firstItem="CEZ-Ju-Tpq" firstAttribute="centerY" secondItem="8bC-Xf-vdC" secondAttribute="centerY" id="vkx-JQ-pOF"/>
</constraints>
</view>
<connections>
<outlet property="screenShotRenderer" destination="CEZ-Ju-Tpq" id="8QB-OE-ib6"/>
<outlet property="viewForScreenShot" destination="Acg-GO-mMN" id="jgL-yn-8kk"/>
</connections>
</viewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="32.799999999999997" y="37.331334332833585"/>
</scene>
</scenes>
</document>

结果

enter image description here enter image description here

小开

IOS10有了新的 API

extension UIView {
func makeScreenshot() -> UIImage {
let renderer = UIGraphicsImageRenderer(bounds: self.bounds)
return renderer.image { (context) in
self.layer.render(in: context.cgContext)
}
}
}
小开

Swift 4更新:

extension UIView {
var screenShot: UIImage?  {
if #available(iOS 10, *) {
let renderer = UIGraphicsImageRenderer(bounds: self.bounds)
return renderer.image { (context) in
self.layer.render(in: context.cgContext)
}
} else {
UIGraphicsBeginImageContextWithOptions(bounds.size, false, 5);
if let _ = UIGraphicsGetCurrentContext() {
drawHierarchy(in: bounds, afterScreenUpdates: true)
let screenshot = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return screenshot
}
return nil
}
}
}
小开 
 // MARK: - Actions
@objc func imageWasSaved(_ image: UIImage, error: Error?, context: UnsafeMutableRawPointer) {
if let error = error {
print(error.localizedDescription)
return
}


print("Image was saved in the photo gallery")
UIApplication.shared.open(URL(string:"photos-redirect://")!)
}
   

func takeScreenshot(of view: UIView) {
     

let bounds = UIScreen.main.bounds
UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.main.scale)


self.view.drawHierarchy(in: self.view.bounds, afterScreenUpdates: true)


let screenshot = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
UIImageWriteToSavedPhotosAlbum(screenshot, self, #selector(imageWasSaved), nil)
}

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