使用 iPad 拍照时的警告

Question

当我使用 iPad 拍照时，控制台上会显示以下消息：

对尚未渲染的视图进行快照会导致快照为空。确保您的视图在快照之前或屏幕更新后的快照之前至少渲染过一次。

这是我拍摄照片并保存的代码：

- (IBAction)selectPhoto:(id)sender {
UIAlertController * alertController = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleActionSheet];
UIAlertAction* camera = [UIAlertAction actionWithTitle:@"Take Photo" style:UIAlertActionStyleDefault
                                               handler:^(UIAlertAction * action)
                         {
                             _imagePickerController = [[UIImagePickerController alloc] init];
                             _imagePickerController.allowsEditing = YES;
                             _imagePickerController.delegate = self;


                             if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
                                 [_imagePickerController setSourceType: UIImagePickerControllerSourceTypeCamera];

                                 _imagePickerController.modalPresentationStyle = UIModalPresentationOverFullScreen;
                                 [self presentViewController:_imagePickerController animated:YES completion:nil];
                             }
                             else {
                                 UIAlertController * alert= [UIAlertController
                                                             alertControllerWithTitle:@"Camera not detected"
                                                             message:@""
                                                             preferredStyle:UIAlertControllerStyleAlert];

                                 UIAlertAction* ok = [UIAlertAction
                                                      actionWithTitle:@"OK"
                                                      style:UIAlertActionStyleDefault
                                                      handler:^(UIAlertAction * action)
                                                      {

                                                      }];
                                 [alert addAction:ok];
                                 [self presentViewController:alert animated:YES completion:nil];
                             }
                         }];
[alertController addAction:camera];
[alertController.view layoutIfNeeded];

UIPopoverPresentationController *pop = alertController.popoverPresentationController;
alertController.popoverPresentationController.sourceRect = self.button.frame;
alertController.popoverPresentationController.sourceView = self.view;
pop.permittedArrowDirections = UIPopoverArrowDirectionAny;
pop.delegate = self;
[self presentViewController:alertController animated:YES completion:nil]; 
}

并获取新图像：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
if ([mediaType isEqualToString:@"public.image"]){
    _img = [info objectForKey:UIImagePickerControllerEditedImage];
    [_button setBackgroundImage:_img forState:UIControlStateNormal];
    [_button setTitle:@"" forState:UIControlStateNormal];
}


[self.imagePickerController dismissViewControllerAnimated:YES completion:nil];
}

点击拍照时出现警告。

Answer 1

希望这会有所帮助：

pragma mark- UIImagePickerController 委托

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage *yourImage = info[UIImagePickerControllerOriginalImage];
    
    [picker dismissViewControllerAnimated:YES completion:nil];
}