如何在启用ARC的情况下检索使用UIImagePickerControllerDelegate拍摄的图像

Question

我有一个应用程序，需要拍摄一张照片，然后向用户展示。我打开相机，让用户使用以下代码拍照：

if ([UIImagePickerController isSourceTypeAvailable: UIImagePickerControllerSourceTypeCamera]) {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.sourceType =
    UIImagePickerControllerSourceTypeCamera;
    imagePicker.mediaTypes = @[(NSString *) kUTTypeImage];
    imagePicker.allowsEditing = NO;
    imagePicker.modalPresentationStyle = UIModalPresentationFullScreen;
    [self presentViewController:imagePicker animated:YES completion:nil];
} else {
    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle: @"Camera failed to open"
                          message: @"Camera is not available"
                          delegate: nil
                          cancelButtonTitle:@"OK"
                          otherButtonTitles:nil];
    [alert show];
}

这提供了相机视图，以便用户可以拍照。我实现了这样的方法来处理取消和完成事件：

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [self dismissViewControllerAnimated:YES completion:nil];
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    [self dismissViewControllerAnimated:YES completion:nil];
    UIImage * image = [info objectForKey:UIImagePickerControllerEditedImage];
    [photoView setImage:image];
    [photoView setNeedsDisplay];
}

问题是，在完成最后一个函数后，图像为零。起初，disseViewControllerAnimated是在函数的末尾，但在这篇SO文章中，答案解释说，应该首先调用disseViewController Animated，并在从信息中获取图像之前释放picker。我试着把disseViewControllerAnimated放在顶部，但因为我使用的是ARC，所以我无法释放picker。

如何从信息中获取图像？

Answer 1

您已经在代码中设置了picker.allowsEditing = NO;。那么，为什么要检索编辑后的图像？它不会存在。无论如何，如果你允许编辑，使用这个：

photoView.image = info[UIImagePickerControllerEditedImage] ? info[UIImagePickerControllerEditedImage] : info[UIImagePickerControllerOriginalImage]

如果用户编辑了照片，则photoView.image将设置为编辑后的照片，否则将设置为原始照片。

如果不允许编辑，只需使用UIImagePickerControllerOriginalImage键即可检索图像。

Answer 2

试试这个：

UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
// or UIImage *image = [info objectForKey:@"UIImagePickerControllerEditedImage"];

Answer 3

检查此方法，

 (void) imagePickerController:(UIImagePickerController *)_picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
      NSLog(@"dictionary image info: %@",info );
    }

在该方法中，打印字典并检查是否获得UIImagePickerControllerMediaType和UIImagePickerControllerOriginalImage。（在我的情况下，我得到的值如下UIImagePickerControllerMediaType="public.image"；UIImagePickerControllerOriginalImage=UIImage:0x1dd79520"；）

现在，如果您正在获取UIImagePickerControllerOriginalImage的值，则将值保存在此UI图像中。

现在使用这个。

UIImage *image = [info objectForKey:@"UIImagePickerControllerEditedImage"];

或

UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

希望这对你有帮助。