如何使用 Xamarin.iOS (C#) 以编程方式截取 iPhone/iPad 的屏幕截图？答案

【问题标题】：How to take a screenshot of the iPhone/iPad programmatically with Xamarin.iOS (C#)?如何使用 Xamarin.iOS (C#) 以编程方式截取 iPhone/iPad 的屏幕截图？
【发布时间】：2013-08-05 21:08:57
【问题描述】：

如何使用 Xamarin.iOS 截取屏幕截图并将此图像存储在 UIImage 中。

我看过几个 Obj-C 的例子，但没有 C#

【问题讨论】：

标签： c# ios xamarin.ios screenshot xamarin

【解决方案1】：

更优雅：

UIScreen.MainScreen.Capture ();

【讨论】：

太棒了！我不知道；）
它返回什么字节[]？还是图片？
UIImage: developer.xamarin.com/api/member/UIKit.UIScreen.Capture()

【解决方案2】：

来自Craig Dunn's网站：

public void ScreenCapture()
{
   var documentsDirectory = Environment.GetFolderPath
                                  (Environment.SpecialFolder.Personal);

   Console.WriteLine("start capture of frame: " + this.View.Frame.Size);
   UIGraphics.BeginImageContext(View.Frame.Size); 
   var ctx = UIGraphics.GetCurrentContext();
   if (ctx != null)
   {
      View.Layer.RenderInContext(ctx);
      UIImage img = UIGraphics.GetImageFromCurrentImageContext();
      UIGraphics.EndImageContext();

      // Set to display in a UIImage control _on_ the view
      imageLogo.Image = img;

      // Save to Photos
      img.SaveToPhotosAlbum(
         (sender, args)=>{Console.WriteLine("image saved to Photos");}
      );

      // Save to application's Documents folder
      string png = Path.Combine (documentsDirectory, "Screenshot.png");
      // HACK: overwrite the splash screen. iSOFlair is the application name
      //string png = Path.Combine (documentsDirectory, "../iSOFlair.app/Default.png");
      NSData imgData = img.AsPNG();
      NSError err = null;
      if (imgData.Save(png, false, out err))
      {
         Console.WriteLine("saved as " + png);
      } else {
         Console.WriteLine("NOT saved as" + png + 
                            " because" + err.LocalizedDescription);
      }
   }
   else
   {
      Console.WriteLine("ctx null - doesn't seem to happen");
   }
}

【讨论】：

【解决方案3】：

更优雅：

public static class UIViewExtensions {

    public static UIImage AsImage(this UIView view) {
        UIGraphics.BeginImageContextWithOptions(view.Bounds.Size, view.Opaque, 0);
        view.Layer.RenderInContext(UIGraphics.GetCurrentContext());
        UIImage img = UIGraphics.GetImageFromCurrentImageContext();
        UIGraphics.EndImageContext();

        return img;
    }

    public static UIImage TakeScreenshot() {
        return UIApplication.SharedApplication.KeyWindow.AsImage();
    }

}

调用 UIViewExtensions.TakeScreenshot() 以截取整个屏幕，或者您可以调用 AsImage() 到任何视图以获取视图的 UIImage 表示。最好将 TakeScreenshot() 方法放在其他地方，因为它不是 UIView 类的扩展。

【讨论】：

【解决方案4】：

此代码将截取照片并将照片保存到相机胶卷中。

 UIGraphics.BeginImageContext(UIScreen.MainScreen.Bounds.Size);
        try
        {
            var mainLayer = UIApplication.SharedApplication.KeyWindow.Subviews[0].Layer;
            mainLayer.RenderInContext(UIGraphics.GetCurrentContext());
            var img = UIGraphics.GetImageFromCurrentImageContext();
            img.SaveToPhotosAlbum((iRef, status) =>
            {
                if (status != null)
                {
                    new UIAlertView("Problem", status.ToString(), null, "OK", null).Show();
                }
                else
                {
                    new UIAlertView("Saved", "Saved", null, "OK", null).Show();
                }
            });
        }
        finally
        {
            UIGraphics.EndImageContext();
        }

但要确保您的应用没有崩溃，请向用户请求将图像保存到相机胶卷的权限。将此添加到 info.plist 中

<key>NSPhotoLibraryAddUsageDescription</key>
<string>This app requires read and write permission from the user.</string>

if you're adding it from the generic editor then "Privacy - Photo Library Additions Usage Description" will be the given option you will find out instead of "NSPhotoLibraryAddUsageDescription".

【讨论】：