Отображение таблиц действий вызывает недопустимые контекстные ошибки CGContext

Я использую таблицу действий для отображения списков данных для пользователя на выбор. Проблема в том, что показ таблицы действий с использованием [self.actionSheet showInView:self.view]; вызывает несколько ошибок CGContext. Тот же код хорошо работал в iOS 6.

код:

self.actionSheet = [[UIActionSheet alloc] initWithTitle:nil
                                             delegate:nil
                                    cancelButtonTitle:nil
                               destructiveButtonTitle:nil
                                    otherButtonTitles:nil];
[self.actionSheet setActionSheetStyle:UIActionSheetStyleBlackOpaque];

CGRect tableFrame = CGRectMake(0, 40, 320, 214);
self.tableView = [[UITableView alloc] initWithFrame:tableFrame style:UITableViewStylePlain];
self.tableView.dataSource = self;
self.tableView.delegate = self;
[self.actionSheet addSubview:self.tableView];

UISegmentedControl *closeButton = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObject:@"Done"]];
closeButton.momentary = YES;
closeButton.frame = CGRectMake(260, 7.0f, 50.0f, 30.0f);
closeButton.tintColor = [UIColor redColor];
[closeButton addTarget:self action:@selector(dismissActionSheet:) forControlEvents:UIControlEventValueChanged];
[self.actionSheet addSubview:closeButton];

[self.actionSheet showFromView:self.view];

[UIView beginAnimations:nil context:nil];
[self.actionSheet setBounds:CGRectMake(0, 0, 320, 485)];
[UIView commitAnimations];

Ошибки:

CGContextSetFillColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextSetStrokeColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextSetFlatness: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextAddPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextDrawPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

Update:

Обходной путь для установки cancelButtonTitle для @"" приводит к этой проблеме интерфейса для меня:

Исходный код пришел из другого ответа stackoverflow, см. qaru.site/info/49534/....

Ответы

   self.startSheet=[[UIActionSheet alloc]initWithTitle:nil
                                           delegate:nil
                                  cancelButtonTitle:@""
                             destructiveButtonTitle:nil
                                  otherButtonTitles:nil];

self.actionSheet = [[UIActionSheet alloc] initWithTitle:@""
                                               delegate:nil
                                      cancelButtonTitle:nil
                                 destructiveButtonTitle:nil
                                      otherButtonTitles:nil];

UIView *background = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
background.backgroundColor = [UIColor colorWithRed:204.0/255.0 green:204.0/255.0 blue:204.0/255.0 alpha:1];
[self.actionSheet addSubview:background];