UIActionSheet与UIPickerView没有显示任何iPad

Question

我在ActionSheet dateSheet中有一个UIPickerview，可以获取用户的人口统计信息。这是我的代码。

    UIPickerView *picker=[[UIPickerView alloc] initWithFrame:CGRectMake(0,125,320,216)];
    picker.tag = 1;
    picker.delegate=self;
    picker.showsSelectionIndicator=YES;
    [dateSheet addSubview:picker];
    [dateSheet showInView:self.view];
    [dateSheet setFrame:CGRectMake(0,220,320,312)];

我改变了代码：

    UIPickerView *picker=[[UIPickerView alloc] initWithFrame:CGRectMake(0,95,320,216)];
    picker.tag = 1;
    picker.delegate=self;
    picker.showsSelectionIndicator=YES;
    [dateSheet addSubview:picker];
    [dateSheet showInView:self.view];
    [dateSheet setFrame:CGRectMake(0, 168, 320, 312)];

但无论哪种方式现在都在iPad模拟器上，它看起来像这样

这是我设置pickerviews数据的地方

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
   return [pickerdata objectAtIndex:row];
}