iPad-显示带有选择器视图的操作表

我正在将picker视图添加到操作表中，这在iPhone中运行良好。但在iPad上，我看不到行动表。我看到iPad屏幕中央有一个小矩形。以下是我编写的代码：

    NSString *actionSheetTitle = @"Select Date of Birth";
    UIActionSheet *dateSheet = [[UIActionSheet alloc] initWithTitle:actionSheetTitle
                                                                         delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil
                                                                otherButtonTitles:@"Done",nil];
    dateSheet.delegate = self;
    dateSheet.actionSheetStyle = UIActionSheetStyleAutomatic;
    dateSheet.destructiveButtonIndex = 0;    // make the second button red (destructive)
    dateSheet.tag = 100;

    //Add the picker
    UIDatePicker *pickerView = [[UIDatePicker alloc] initWithFrame:CGRectMake(0,185,0,0)];
    pickerView.datePickerMode = UIDatePickerModeDate;
    [pickerView addTarget:self action:@selector(dateSelectionChanged:) forControlEvents:UIControlEventValueChanged];
    [dateSheet addSubview:pickerView];
    [dateSheet showInView:self.view];
    [dateSheet setBounds:CGRectMake(0,0,320,700)];

    self.tempDob = self.dob;
    if (self.editPatientDetails)
    {
        NSDateFormatter* dtFormatter = [[NSDateFormatter alloc] init];
        [dtFormatter setDateFormat:@"MM/dd/yyyy"];
        NSDate* dateSelected = [dtFormatter dateFromString:self.dob];
        [dtFormatter release];
        [pickerView setDate:dateSelected animated:YES];     
    }

    [pickerView release];
    [dateSheet release];    

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行动表在iPad中显示为选择器视图。这是预期的行为