Невозможно добавить UIDatePicker в UIActionSheet

Я хочу добавить UIDatePicker в UIActionSheet, код приведен ниже:

UIActionSheet* actionSheet = [[UIActionSheet alloc] initWithTitle:@"DEMO" delegate:self cancelButtonTitle:@"Cancle" destructiveButtonTitle:nil otherButtonTitles:nil];


 actionSheet = [[UIActionSheet alloc] initWithTitle:@"Ratings" 
                                                  delegate:self
                                         cancelButtonTitle:@"Cancel"
                                    destructiveButtonTitle:nil
                                         otherButtonTitles:nil];

UIDatePicker *pickerView = [[UIDatePicker alloc] init];
pickerView.datePickerMode = UIDatePickerModeDate;

[actionSheet addSubview:pickerView];
[actionSheet showInView:self.view];   
[actionSheet sendSubviewToBack:pickerView];  

[actionSheet showInView:self.view];
[actionSheet setBounds:CGRectMake(0,0,320, 500)];

CGRect pickerRect = pickerView.bounds;
pickerRect.origin.y = -100;
pickerView.bounds = pickerRect;

[pickerView release];
[actionSheet release];

Вопрос в том, почему этот код не может работать в режиме iPad, в то время как он работает в режиме iphone