Objective c 在横向模式下，UIActionSheet上的UIPickerView显示为黑色

我有一个通过UIActionSheet更新表行的应用程序。在这张纸上，我展示了一个UIPickerView。UIPickerView在iphone上运行良好，外观非常逼真。但当我在横向模式下打开它时，它仍然工作，但是轮廓区域显示为黑色，未选择的数字也为黑色

下面是一个屏幕截图和代码。有什么明显的问题吗

// create enough space for the UIPicker to show up above the selection button
NSString *title = @"\n\n\n\n\n\n\n\n\n\n\n\n";

if ((UIDeviceOrientationIsLandscape([UIDevice currentDevice].orientation)) &&
    (UI_USER_INTERFACE_IDIOM() != UIUserInterfaceIdiomPad)) {
    title = @"\n\n\n\n\n\n\n\n\n";
}


UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:title delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:NSLocalizedString(@"Choose", @"Click to finilize Value - Timer"), nil];
[actionSheet showInView:viewController.view];

UIDatePicker *pickerView = [[UIDatePicker alloc] init];
[pickerView setDatePickerMode: UIDatePickerModeCountDownTimer];
if (timerInterval == 0) timerInterval = 5;
[pickerView setMinuteInterval: timerInterval];
[pickerView setCountDownDuration: [timerRec.timerDuration intValue]];

pickerView.tag = 101;

if ((UIDeviceOrientationIsLandscape([UIDevice currentDevice].orientation)) &&
    (UI_USER_INTERFACE_IDIOM() != UIUserInterfaceIdiomPad)) {
    pickerView.frame = CGRectMake(0,0, 50,50);
}

//pickerView.delegate = self;
//pickerView.dataSource = self;
//ickerView.showsSelectionIndicator = YES;

[actionSheet addSubview:pickerView];

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我已经调试了一些。我发现，当UIDatePicker为：[pickerView setDatePickerMode:UIDatePickerModeTime]时，一切正常，但使用[pickerView setDatePickerMode:UIDatePickerModeCountDownTimer]时，问题就出现了。所以这只是倒计时。我有完全相同的问题！你有什么收获吗？