Only the current date is displayed blank in UIDatePicker, is there a way to display it normally? (It does not occur in the simulator, it occurs in the actual machine. Occasionally, the event does not occur even in the actual machine.)    __weak IBOutlet UIDatePicker *_datePicker;    [_datePicker setPreferredDatePickerStyle:UIDatePickerStyleWheels];     [_datePicker setDatePickerMode:UIDatePickerModeDate];     [_datePicker setMaximumDate:_maximumDate]; [_datePicker setMinimumDate:_minimumDate];     [_datePicker setBackgroundColor:[UIColor whiteColor]];    [_datePicker setValue:[UIColor blackColor] forKey:@"textColor"];