用ALAssetsLibrary将过滤后图片写入照片库

转载自:http://blog.sina.com.cn/s/blog_61235faa0100z3dp.html

CIImage *saveToSave = [filter outputImage];

CGImageRef cgImg = [context createCGImage:saveToSave fromRect:[saveToSave extent]];
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library writeImageToSavedPhotosAlbum:cgImg
                             metadata:[saveToSave properties]
                      completionBlock:^(NSURL *assetURL, NSError *error) {
                                       CGImageRelease(cgImg);                              }];