ios - 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照然后显示给用户。我使用以下代码打开相机让用户拍照:

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];
}

这会呈现相机 View ，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 dismissViewControllerAnimated 在函数的末尾，但在 this SO post 中答案解释说应该首先调用 dismissViewControllerAnimated 并且应该在从信息中获取图像之前释放选择器。我尝试将 dismissViewControllerAnimated 放在顶部，但因为我使用的是 ARC，所以我无法释放选择器。

如何从信息中获取图片？

Answer 1

您已在代码中设置了 picker.allowsEditing = NO;。那你为什么要检索编辑过的图像？它不会存在。不管怎样，如果你允许编辑，使用这个:

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

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

如果您不允许编辑，只需使用 UIImagePickerControllerOriginalImage 键检索图像即可。