问不符合条件的无效参数:日期

EN

datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 40, 0, 0)];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    NSString *startTimeString = [MathFunctions minutesToTimeString:[appointment.start_time integerValue]];
    NSLog(@"Time: %@",startTimeString);
    NSLog(@"Date: %@", appointment.date);
    [dateFormatter setDateFormat:@"yyyyMMdd h:mm a"];
    [Crashlytics setObjectValue:[NSString stringWithFormat:@"%@ %@", appointment.date, startTimeString] forKey:@"ResAddDate"];
    NSString *dateTimeString = [NSString stringWithFormat:@"%@ %@", appointment.date, startTimeString];
    NSLog(@"Date String: %@", dateTimeString);
    datePicker.date = [dateFormatter dateFromString:dateTimeString];

CoreFoundation  
__exceptionPreprocess + 162
1    libobjc.A.dylib    
objc_exception_throw + 32
2    CoreFoundation 
+[NSException raise:format:]
3    Foundation 
-[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 90
4    UIKit  
-[UIDatePickerView _updateBitsForDate:forced:andReload:animateIfNeeded:] + 146
5    UIKit  
-[UIDatePickerView _setDate:animated:forced:] + 348
6    UIKit  
-[UIDatePickerView setDate:animated:] + 30
7    UIKit  
-[UIDatePicker setDate:] + 36
8    MyApp   ReserveAddController.m line 283
-[ReserveAddController showDatePicker] + 283
9    MyApp   ReserveAddController.m line 179
-[ReserveAddController tableView:didSelectRowAtIndexPath:] + 179
10   UIKit  
-[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 944
11   UIKit  
-[UITableView _userSelectRowAtPendingSelectionIndexPath:] + 158
12
Foundation  
__NSFireDelayedPerform + 414
13   CoreFoundation 
__CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 14
14   CoreFoundation 
__CFRunLoopDoTimer + 364
15   CoreFoundation 
__CFRunLoopRun + 1206
16   CoreFoundation 
CFRunLoopRunSpecific + 300
17   CoreFoundation 
CFRunLoopRunInMode + 104
18   GraphicsServices   
GSEventRunModal + 136
19   UIKit  
UIApplicationMain + 1080
20   Appointment-Plus    main.m line 16
main + 16
21   Appointment-Plus