iOS6 Getting image from Photo Library

What you would need to do to capture a image from a local photo library.

First ensure that the controller you create works these delegates;

<UIImagePickerControllerDelegate, UINavigationControllerDelegate>

Method to Start request to grab the image;

- (void) useCameraRoll:(id)sender
{
    if ([UIImagePickerController isSourceTypeAvailable:
          UIImagePickerControllerSourceTypeSavedPhotosAlbum])
    {
       UIImagePickerController *imagePicker =
           [[UIImagePickerController alloc] init];
       imagePicker.delegate = self;
       imagePicker.sourceType =
           UIImagePickerControllerSourceTypePhotoLibrary;
        imagePicker.mediaTypes = @[(NSString *) kUTTypeImage];
       imagePicker.allowsEditing = NO;
       [self presentViewController:imagePicker 
           animated:YES completion:nil];
       _newMedia = NO;
    }
}

Delegate Methods to Receive the Image;

#pragma mark -
#pragma mark UIImagePickerControllerDelegate

-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
   NSString *mediaType = info[UIImagePickerControllerMediaType];

   [self dismissViewControllerAnimated:YES completion:nil];

    if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
        UIImage *image = info[UIImagePickerControllerOriginalImage];

        _imageView.image = image;
        if (_newMedia)
            UIImageWriteToSavedPhotosAlbum(image,
               self,
               @selector(image:finishedSavingWithError:contextInfo:),
               nil);
        }
        else if ([mediaType isEqualToString:(NSString *)kUTTypeMovie])
        {
                // Code here to support video if enabled
        }
}

-(void)image:(UIImage *)image
finishedSavingWithError:(NSError *)error
contextInfo:(void *)contextInfo
{
   if (error) {
        UIAlertView *alert = [[UIAlertView alloc]
           initWithTitle: @"Save failed"
           message: @"Failed to save image"
           delegate: nil
           cancelButtonTitle:@"OK"
           otherButtonTitles:nil];
        [alert show];
   }
}

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
   [self dismissViewControllerAnimated:YES completion:nil];
}

References:  Accessing the iPhone Camera and Photo Library (iOS 6)