Как сделать снимок экрана UIView?

Question

Мне интересно, как мое приложение для iPhone может сделать снимок экрана определенного UIView как UIImage.

Я попробовал этот код, но все, что я получил, это пустое изображение.

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

myUIView имеет размеры 320x480 и имеет несколько подвидов. Как правильно это сделать?

Answer 1

Swift 4 обновлено:

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
        }
    }
}

Answer 2

Подробнее

xCode 8.2.1, Swift 3

Снимок экрана UIView в 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
    }
}

Использование

screenShotRenderer.image = viewForScreenShot.screenShot

Полный пример использования

Просмотр контроллера с расширением UIView

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

<?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>

Результат

Answer 3

Для снятия скриншота используется следующий фрагмент:

UIGraphicsBeginImageContext(self.muUIView.bounds.size);

[myUIView.layer renderInContext:UIGraphicsGetCurrentContext()];

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

Используйте метод renderInContext: вместо drawInContext: метод

renderInContext: метод визуализирует получателя и его подслои в текущий контекст. Этот метод визуализирует прямо из дерева слоев.

Answer 4

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

  return image;
}

Answer 5

Вы можете использовать следующую категорию UIView -

@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