iOS开发 自拍及照片镜面翻转问题解决办法

参考链接：https://cloud.tencent.com/developer/ask/sof/432242

项目开发中经常遇到采集人脸照片的需求，需要调用相机的自拍功能。自拍后会发现照片是镜面翻转的，而项目要求使用原图，解决办法如下：

@interface ViewController()<UIImagePickerControllerDelegate>

@property (nonatomic,strong) UIImagePickerController *picker;

@end

- (void)viewDidLoad {
    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(imageTaken) name:@"_UIImagePickerControllerUserDidCaptureItem" object:nil]; //监听拍照完成的动作
}

//拍照
- (void)takePhoto {
    
    _picker = [[UIImagePickerController alloc]init];
    _picker.sourceType = UIImagePickerControllerSourceTypeCamera;
    
    _picker.cameraDevice = UIImagePickerControllerCameraDeviceFront; //自拍
    _picker.delegate = self;
    [self presentViewController:_picker animated:YES completion:nil];
}

#pragma mark - UIImagePickerControllerDelegate

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<UIImagePickerControllerInfoKey,id> *)info{
    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
    UIImage* flippedImage = [UIImage imageWithCGImage:image.CGImage
                                                scale:image.scale
                                          orientation:UIImageOrientationLeftMirrored];  //镜面翻转图片
}

- (void)imageTaken {

    if (_picker.cameraDevice == UIImagePickerControllerCameraDeviceFront) { //如果是自拍则翻转预览图
        NSMutableArray *subviews = [NSMutableArray arrayWithObject:_picker.view];
        while ([subviews count] != 0) {
            UIView *subview = [subviews firstObject];
            [subviews removeObjectAtIndex:0];
            [subviews addObjectsFromArray:subview.subviews];
            if ([subview isKindOfClass:[UIImageView class]]) {
                subview.transform = CGAffineTransformScale(_picker.cameraViewTransform, -1, 1);
            }
        }
    }
}