iPad上调用UIImagePickerViewController，与iPhone调用略有不同

iPad上调用UIImagePickerViewController，与iPhone调用略有不同。

-(void) pickImage{    UIImagePickerController *m_imagePicker = [[UIImagePickerController alloc] init];    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {        m_imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;        m_imagePicker.delegate = self;        [m_imagePicker setAllowsEditing:NO];        UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:m_imagePicker];        self.popoverController = popover;                [popoverController presentPopoverFromRect:CGRectMake(0, 0, 300, 300) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];        [popover release];        [m_imagePicker release];    }else {        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Error accessing photo library!" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];        [alert show];        [alert release];    }}