renderInContext不捕获旋转的子视图

Question

添加了一个UIImageVIew(imageView)self.view,捕获视图到相册完美地工作:

 CGSize size = CGSizeMake(self.view.frame.size.height, self.view.frame.size.width);
 UIGraphicsBeginImageContext(size);
 [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
 UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
 UIGraphicsEndImageContext();
 UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);

但是,如果imageView子视图通过以下方式旋转:

 [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];

self.view再次捕获并不反映旋转.子视图imageView好像没有旋转.

如何使renderInContext子视图旋转CABasicAnimation？

更新:

警告:CALayer/-renderInContext:方法未实现完整的Core Animation组合模型.下面提供的代码将能够解决大多数情况,但有些事情CALayer/-renderInContext:方法无法正确呈现,因此您可能希望联系开发人员技术支持部门以获取变通方法请求.

官方Apple技术问答QA1703建议联系开发人员技术支持以获取变通请求.

是否已存在解决方法？

Answer 1

使用layer.presentationLayer而不是layer时候renderInContext.

这是一个截取UIView,UIView + Screenshot.h的截图的类别:

 //
 //  UIView+Screenshot.h
 //
 //  Created by Horace Ho on 2012/12/11.
 //  Copyright (c) 2012 Horace Ho. All rights reserved.
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
 // in the Software without restriction, including without limitation the rights
 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 // copies of the Software, and to permit persons to whom the Software is
 // furnished to do so, subject to the following conditions:
 //
 // The above copyright notice and this permission notice shall be included in
 // all copies or substantial portions of the Software.
 //
 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.

 @interface UIView (HHScreenShot)
 - (UIImage *)screenshot:(UIDeviceOrientation)orientation isOpaque:(BOOL)isOpaque usePresentationLayer:(BOOL)usePresentationLayer;
 @end

 @implementation UIView (HHScreenShot)

 - (UIImage *)screenshot:(UIDeviceOrientation)orientation isOpaque:(BOOL)isOpaque usePresentationLayer:(BOOL)usePresentationLayer
 {
     CGSize size;

     if (orientation == UIDeviceOrientationPortrait || orientation == UIDeviceOrientationPortraitUpsideDown) {
         size = CGSizeMake(self.frame.size.width, self.frame.size.height);
     } else {
         size = CGSizeMake(self.frame.size.height, self.frame.size.width);
     }

     UIGraphicsBeginImageContextWithOptions(size, isOpaque, 0.0);

     if (usePresentationLayer) {
         [self.layer.presentationLayer renderInContext:UIGraphicsGetCurrentContext()];
     } else {
         [self.layer renderInContext:UIGraphicsGetCurrentContext()];
     }

     UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

     UIGraphicsEndImageContext();

     return image;
 }

 @end

使用:

 UIImage *image = [self.view screenshot:UIDeviceOrientationPortrait
                               isOpaque:YES 
                   usePresentationLayer:YES];