Ios 如何使用allowsEditing

我只想让用户在应用程序中拍照→作物→拯救所以我想使用UIImagePickerControl的allowsEditing属性。但是我不知道我怎么能做到。这是我到目前为止的相机代码

-(IBAction)TakePhoto {
    picker = [[UIImagePickerController alloc]init];
    picker.delegate = self;
    [picker setSourceType:UIImagePickerControllerSourceTypeCamera];
    [self presentViewController:picker animated:YES completion:NULL];

}

---

使用此选项从相机中拾取照片

- (IBAction)takePhoto:(UIButton *)sender {

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;

[self presentViewController:picker animated:YES completion:NULL];   
}

使用此选项从照片库中拾取照片

- (IBAction)selectPhoto:(UIButton *)sender {

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

[self presentViewController:picker animated:YES completion:NULL];

}

使用以下两种委托方法

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
self.imageView.image = chosenImage;

[picker dismissViewControllerAnimated:YES completion:NULL];

}

}

将此添加到ViewDidLoad方法中，以便如果您的设备不支持摄像头，则显示此警报消息

if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

    UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                    message:@"Device has no camera"
                                                    delegate:nil
                                                    cancelButtonTitle:@"OK"
                                                    otherButtonTitles: nil];

    [myAlertView show];

}

将这两个协议添加到AppViewController.h文件：

@interface APPViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>

@接口APPViewController:UIViewController

我有太多错误。。我找不到什么是错误的。一个在VIEWDIDLoad方法之后没有完成。图像裁剪卡卡在中间，有什么修正吗？

@interface APPViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>