如何获取UIView的屏幕快照?

I am wondering how my iPhone app can take a screen shot of a specific UIView as a UIImage.

我想知道我的iPhone应用程序如何将一个特定的UIView作为一个UIImage的屏幕快照。

I tried this code but all I get is a blank image.

我尝试了这个代码，但是我得到的只是一个空白的图像。

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

myUIView has dimensions 320x480 an it has some sub-views. What is the correct way to do this?

myUIView有320x480尺寸它有一些子视图。正确的做法是什么?

14 个解决方案

#1

I think you may want renderInContext, not drawInContext. drawInContext is more a method you would override...

我想你可能想要renderInContext，而不是drawInContext。drawInContext更像是一个你可以重写的方法。

Note that it may not work in all views, specifically a year or so ago when I tried to use this with the live camera view it did not work.

请注意，它可能不能在所有视图中工作，特别是在大约一年前，当我尝试将它与实时相机视图一起使用时，它不能工作。

#2

iOS 7 has a new method that allows you to draw a view hierarchy into the current graphics context. This can be used to get an UIImage very fast.

ios7有一个新方法，可以在当前图形上下文中绘制视图层次结构。这可以用来快速获取UIImage。

I implemented a category method on UIView to get the view as an UIImage:

我在UIView上实现了一个category方法将view作为UIImage:

- (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;
}

It is considerably faster then the existing renderInContext: method.

它比现有的renderInContext:方法快得多。

Reference: https://developer.apple.com/library/content/qa/qa1817/_index.html

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

UPDATE FOR SWIFT: An extension that does the same:

SWIFT更新:一个与此相同的扩展:

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
    }
}

UPDATE FOR SWIFT 3

更新快3

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

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

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

#3

You need to capture the key window for a screenshot or a UIView. You can do it in Retina Resolution using UIGraphicsBeginImageContextWithOptions and set its scale parameter 0.0f. It always captures in native resolution (retina for iPhone 4 and later).

您需要捕获屏幕快照或UIView的键窗口。你可以在视网膜分辨率使用UIGraphicsBeginImageContextWithOptions并设置它的比例参数0.0f。它总是以本地分辨率(iPhone 4和之后的视网膜)捕获。

This one does a full screen screenshot (key window)

这个是全屏截图(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();

This code capture a UIView in native resolution

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();

This saves the UIImage in jpg format with 95% quality in the app's document folder if you need to do that.

如果你需要这样做的话，这可以节省jpg格式的UIImage，在应用程序的文档文件夹中有95%的质量。

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

#4

iOS7 onwards, we have below default methods :

iOS7向前，我们有以下默认的方法:

- (UIView *)snapshotViewAfterScreenUpdates:(BOOL)afterUpdates

Calling above method is faster than trying to render the contents of the current view into a bitmap image yourself.

调用上述方法比自己将当前视图的内容呈现为位图映像要快。

If you want to apply a graphical effect, such as blur, to a snapshot, use the drawViewHierarchyInRect:afterScreenUpdates: method instead.

如果您想对快照应用图形效果，比如blur，请使用drawViewHierarchyInRect:afterScreenUpdates: method。

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

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

#5

I have created usable extension for UIView to take screenshot in Swift:

我已经为UIView创建了可用的扩展，可以在Swift中截图:

extension UIView{

var screenshot: UIImage{

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

To use it just type:

使用它只是类型:

let screenshot = view.screenshot

#6

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

This method may put in your Controller class.

这个方法可以放在您的Controller类中。

#7

CGImageRef UIGetScreenImage();

Apple now allows us to use it in a public application, even though it's a private API

苹果现在允许我们在公共应用程序中使用它，即使它是一个私有的API

#8

Apple does not allow:

苹果不允许:

CGImageRef UIGetScreenImage();

CGImageRef UIGetScreenImage();

Applications should take a screenshot using the drawRect method as specified in: http://developer.apple.com/library/ios/#qa/qa2010/qa1703.html

应用程序应该使用drawRect方法进行截屏，如以下所示:http://developer.apple.com/library/ios/#qa/qa2010/qa1703.html

#9

I created this extension for save a screen shot from UIView

我创建了这个扩展，用于从UIView保存屏幕截图

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)

}}

call:

电话:

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

If you want to create a png must change:

如果你想创建一个png，必须改变:

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

by

通过

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

#10

The following snippet is used to take screenshot :

以下片段用于截图:

UIGraphicsBeginImageContext(self.muUIView.bounds.size);

[myUIView.layer renderInContext:UIGraphicsGetCurrentContext()];

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

Use renderInContext: method instead of drawInContext: method

使用renderInContext:方法而不是drawInContext:方法

renderInContext: method renders the receiver and its sublayers into current context. This method renders directly from the layer tree.

renderInContext:方法将接收者及其子类呈现到当前上下文中。此方法直接从层树中呈现。

#11

Details

xCode 8.2.1, Swift 3

xCode 8.2.1中,斯威夫特3

UIView Screen Shot in Swift

import UIKit

extension UIView {

    var screenShot: UIImage?  {
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, 1.0);
        if let _ = UIGraphicsGetCurrentContext() {
            drawHierarchy(in: bounds, afterScreenUpdates: true)
            let screenshot = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            return screenshot
        }
        return nil
    }
}

Usage

screenShotRenderer.image = viewForScreenShot.screenShot

Сomplete example of the use

View controller with UIView extension

带有UIView扩展名的视图控制器

import UIKit

class ViewController: UIViewController {

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

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

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

extension UIView {

    var screenShot: UIImage?  {
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, 1.0);
        if let _ = UIGraphicsGetCurrentContext() {
            drawHierarchy(in: bounds, afterScreenUpdates: true)
            let screenshot = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            return screenshot
        }
        return nil
    }
}

Main.storyboard

Main.storyboard

<?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="*_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>

Result

#12

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

  return image;
}

#13

There is new API from iOS 10

iOS 10有新的API

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

#14

you can use following UIView category -

你可以使用以下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