在 UIImagePickerController 之后打开新 ViewController 的问题

Question

我试图在我的 UIImagePickerController 的委托函数返回“didFinishPickingImage”后立即打开一个新视图 (UnprocessedPhotoViewController)。

不幸的是，我似乎可以打开 UIImagePickerController 模态视图，或者切换到 UnprocessedPhotoViewController 作为模态视图，但不能同时按顺序进行。

在下面的代码中，按下按钮会激活 pickPhoto IBAction。此代码成功激活 UIImagePickerController。用户选择图像后，调用 didFinishPickingImage 委托函数，将图像存储到变量中，尝试关闭 UIImagePickerController 模态并在新模态中打开 UnprocessedPhotoViewController。

注意：如果我注释掉 ImagePicker 并直接运行“showPhoto”，UnprocessedPhotoViewController 显示成功。此外，如果我创建一个新按钮来启动任一视图，它会成功运行，但我无法按顺序启动视图。我希望在用户选择图像后，将启动新视图，允许用户处理图像。

保证 ImagePicker modal 关闭然后打开 UnprocessedPhotoViewController 的正确方法是什么？

谢谢！！！

代码：

- (IBAction)pickPhoto:(id)sender{

//TODO: To be replaced with the gallery control launching code

// Load Image Selection Code    
self.imgPicker = [[UIImagePickerController alloc] init];
self.imgPicker.delegate = self;
self.imgPicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentModalViewController:self.imgPicker animated:YES];

}



// Dummy function assumes you either picked (or took a picture =D) of Angie and moves you right to the unprocessed viewing screen.
- (void) showPhoto{

// Start new view controller
[self dismissModalViewControllerAnimated:YES];
UnprocessedPhotoViewController *upViewController = [[UnprocessedPhotoViewController alloc] initWithNibName:@"UnprocessedPhotoViewController" bundle:nil];
upViewController.imageView.image = selectedImage;
upViewController.delegate = self;
upViewController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:[upViewController animated:YES]];
[upViewController release];

}


- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)img {
selectedImage = img;
[[picker parentViewController] dismissModalViewControllerAnimated:YES];
[self dismissModalViewControllerAnimated:YES];

[self showPhoto];
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
[[picker parentViewController] dismissModalViewControllerAnimated:YES];
}

Answer 1

在你的根视图控制器中实现 viewDidAppear 并根据成员数据决定是否调用 showPhoto。下面的示例只是简单地重新呈现了 UIImagePicker，但任何新的模态视图都可以使用。每当您的根视图控制器的视图出现时都会调用 viewDidAppear，因此您必须确保在调用它时知道上下文。但这是确定模态视图控制器已消失的确定方法。

- (IBAction) showPicker: (id) sender
{
    UIImagePickerController* picker = [[[UIImagePickerController alloc] init] autorelease];
    picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    picker.delegate = self;
    picker.allowsEditing = YES;

    [self presentModalViewController:picker animated:YES];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    imageChosen = YES;

    [self dismissModalViewControllerAnimated:YES];
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    imageChosen = NO;

    [self dismissModalViewControllerAnimated:YES];
}

- (void) viewDidAppear: (BOOL) animated
{
    if ( imageChosen )
    {
        [self showPicker: self];
    }
}

Answer 2

另一种方法是使用您自己的动画包装内置的解雇动画，然后捕获 animationDidStop “事件”。这会创建一个复合动画，因此当内置动画完成时，您的（空）包装动画会完成并提醒您完成。

这比这里的其他答案略干净，IMO，因为您不需要保留状态变量或覆盖 viewDidAppear:（在我的应用程序中，呈现选择器的视图控制器是从处理选择器管理的实用程序代码，这意味着任何使用我的共享实用程序的视图控制器都必须覆盖viewDidAppear:，否则无法工作）：

-(void)dismissalAnimationDone:(NSString*)animationID 
                     finished:(BOOL)finished context:(void*)context
{
    UIImage* image = (UIImage*) context;
    // present controllers as you please
}

-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info
{
    [UIView beginAnimations:@"dismissal wrapper" context:image];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(dismissalAnimationDone:finished:context:)];

    [self.delegate dismissModalViewControllerAnimated:YES];

    [UIView commitAnimations];
}