Ios 运行时将UIDatePicker添加到UIView的问题

我试图在用户单击按钮时将UIDatePicker添加到UIView。我有一个从底部向上滑动UIView的动画设置。如果我将UIDatePicker添加到ViewControllers视图，则日期选择器将正确显示。但是，如果我将日期选择器添加到UIView，则日期选择器根本不会显示

- (IBAction)setTimeButtonPressed:(UIButton *)sender
{
    // Creates Frame Rects for views and controls
    CGRect datePickerViewOutFrame = CGRectMake(0, 336, self.view.frame.size.width, 228);
    CGRect datePickerOutFrame = CGRectMake(0, 336, self.view.frame.size.width, 162);

    // Create View that will slide out
    UIView *datePickerView = [[UIView alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height, self.view.frame.size.width, 0)];
    datePickerView.backgroundColor = [UIColor flatCloudsColor];

    // Setup DatePicker
    UIDatePicker *datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height, self.view.frame.size.width, 0)];
    datePicker.datePickerMode = UIDatePickerModeTime;
    datePicker.date = [NSDate date];
    datePicker.hidden = NO;

    [self.view addSubview:datePickerView]; 
    [datePickerView addSubview:datePicker]; /* DOES NOT WORK*/

    self.datePickerView.clipsToBounds = YES;

    // Animate the views sliding out from the bottom
    [UIView animateWithDuration:0.5
                          delay:0
                        options:UIViewAnimationOptionCurveLinear
                     animations:^{
                         datePicker.frame = datePickerOutFrame;
                         datePickerView.frame = datePickerViewOutFrame;

                     }
                     completion:^(BOOL finished){
                         // Might need later
                     }];
}

但是，如果我更改了添加datePicker的行，它可以工作，但是我不能将它剪裁到datePickerView的边界

[self.view addSubview:datePickerView];
[self.view addSubview:datePicker];  /* Works but can't clip DatePicker */

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我做错了什么

UIDatePickerView框架需要相对于其父视图。因此，如果要将其添加到

datePickerView

，则

UIDatePicker

的框架的原点应为

0,0

，而不是基于视图控制器视图的高度

UIDatePicker *datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 0)];

---

啊，我知道我错过了什么。谢谢，这就成功了！