UIImagePickerController问题？

Question

这是我提供UIImagePickerController的代码:

// Show the media browser with our settings, then the browser will call our delegate if needed
- (BOOL) startMediaBrowserFromViewController: (UIViewController*) controller
                               usingDelegate: (id <UIImagePickerControllerDelegate,
                                               UINavigationControllerDelegate>) delegate {

    if (([UIImagePickerController isSourceTypeAvailable:
          UIImagePickerControllerSourceTypeSavedPhotosAlbum] == NO)
        || (delegate == nil)
        || (controller == nil))
        return NO;

    UIImagePickerController *mediaUI = [[[UIImagePickerController alloc] init] autorelease];
    mediaUI.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;

    // Check for images type
    NSArray * availableTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeSavedPhotosAlbum];
    BOOL imgsOnlyAvailable = NO;
    // Check if we have only images 
    for (int i = 0; i < [availableTypes count]; i++) {
        // Convert the type
        CFStringRef type = (CFStringRef) [availableTypes objectAtIndex:i];
        if (CFStringCompare ((CFStringRef) type, kUTTypeImage, 0) == kCFCompareEqualTo) {
            // We have images
            imgsOnlyAvailable = YES;
            break;
        }
    }

    // Check if they are available
    if (imgsOnlyAvailable == NO) 
        return NO;

    // Displays only saved pictures from the Camera Roll album.
    mediaUI.mediaTypes = [NSArray arrayWithObject:(id) kUTTypeImage];

    // Hides the controls for moving & scaling pictures, or for
    // trimming movies. To instead show the controls, use YES.
    mediaUI.allowsEditing = NO;

    mediaUI.delegate = delegate;

    [controller presentModalViewController: mediaUI animated: YES];
    return YES;
}

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

    NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType];
    UIImage *originalImage;

    // Handle a still image picked from a photo album
    if (CFStringCompare ((CFStringRef) mediaType, kUTTypeImage, 0)
        == kCFCompareEqualTo) {

        originalImage = (UIImage *) [info objectForKey:
                                     UIImagePickerControllerOriginalImage];    
        // Set image
        self.imgPic.image = originalImage;

        // Now set the button to enabled
        self.btnToText.enabled = YES;
    }

    // Hide picker selector
    [[picker parentViewController] dismissModalViewControllerAnimated: YES];
    [picker release];
}

问题是每当我尝试单击UIImagePickerController中的图像时没有任何反应(通常它选择图像然后将关闭控制器)

有没有理由为什么会出现这样的错误？

谢谢!

// Select the image
- (IBAction)btnSelectFileTouchUp:(id)sender {

    // Start the media browser
    if ([self startMediaBrowserFromViewController:self usingDelegate:self] == NO) {
        // Can't open the media browser
        UIAlertView * alrt = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Can't open the photo media browser in this device" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

        [alrt show];
        [alrt release];
    }
}

Answer 1

检查出的文档parentViewController中的UIViewController类参考.特别是这个小小的花絮.

在iOS 5.0之前,如果视图没有父视图控制器并且以模态方式呈现,则将返回呈现它的视图控制器.这已不再是这种情况.您可以使用presentViewController属性获取呈现视图控制器.

在这个例子中,我希望parentViewControlleriOS 5上的nil为nil,这就是控制器不会解散的原因.尝试更换parentViewController用presentingViewController.

更新:您必须检查是否存在presentingViewControlleron UIViewController以提供iOS版本<5.0的行为.

UIViewController *dismissingController = nil;

if ([self respondsToSelector:@selector(presentingViewController)])
    dismissingController = self.presentingViewController;
else
    dismissingController = self.parentViewController;

[dismissingController dismissModalViewControllerAnimated:YES];