将 NSString 添加到 NSMutableArray 崩溃

Question

在我的 iOS 应用程序中，我有一个 UI 有两个东西：一个选择器视图和一个按钮。

我使用 NSMutableArray 初始化我的选择器视图，如下所示：

@interface ViewController ()
{
    NSMutableArray *_pickerDataCategory;
}
- (void)viewDidLoad
{
   // Initialize Data
    _pickerDataCategory = [[NSMutableArray alloc] init];

    NSMutableArray  *array = [NSMutableArray arrayWithObjects:
                            @"cat1", @"cat2", @"cat3", @"cat4", nil ];

    _pickerDataCategory = array;

 //First I had initialize like this :  NSMutableArray  *_pickerDataCategory = [NSMutableArray arrayWithObjects:
                            @"cat1", @"cat2", @"cat3", @"cat4", nil ];
}

然后我有一个按钮，它显示一个弹出窗口，用户可以在其中写东西。此方法的目的是 添加一个新的 NSString 对象到我的 NSMutableArray.

   - (IBAction)addNewCategory:(id)sender {
        __block bool isNotExist = false;
           UIAlertController * alertController = [UIAlertController alertControllerWithTitle: @"Add new category"
                                                                                  message: @"Please write a new category"
                                                                           preferredStyle:UIAlertControllerStyleAlert];
        [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
            textField.placeholder = @"Category";
            textField.textColor = [UIColor blueColor];
            textField.clearButtonMode = UITextFieldViewModeWhileEditing;
            textField.borderStyle = UITextBorderStyleRoundedRect;
        }];
    UIAlertAction *cancel = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        [alertController dismissViewControllerAnimated:YES completion:nil];
    }];

    UIAlertAction *ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        NSString *input = alertController.textFields[0].text;
        //Check if the category exist already

        for (NSString *category in _pickerDataCategory)
        {
            if ([category isEqualToString:input])
            {
                 [self popupMessage:@"Category already exists" title:@"Error"];
                isNotExist = false;
                return;
            }else{
                NSString *msg = [@"Category has been added : " stringByAppendingString:input];
                 [self popupMessage:msg title:@"Ok"];
                isNotExist = true;


                //[_pickerDataCategory addObject:input];//CRASH
              //  [_picker_cateogry reloadAllComponents];

            }
        }



    }];

    [alertController addAction:cancel];
    [alertController addAction:ok];

    [self presentViewController:alertController animated:YES completion:nil];

}

但是当我想将文本字段输入添加到我的 NSMutableArray 时它崩溃了。我真的不明白为什么。我对我的 NSMutableArray 的初始化很小心。我在 Internet 上查找了有关它的任何信息，我发现的两个信息要么是关于初始化的，要么是关于它是可变数组而不是简单数组的。

此外，我不明白为什么我在 [self presentViewController:alertController animated:YES completion:nil]; 之后添加一些代码，它没有被执行...我也没有找到任何相关信息。

你能帮我弄清楚为什么它崩溃了，它不工作吗？感谢

Answer 1

就您的崩溃而言，这可能与您在枚举数组时试图修改它有关。我会把它们分成两个单独的任务。

类似...

NSMutableArray *additionalObjects = [[NSMutableArray alloc] init];

for (NSString *category in _pickerDataCategory) {
    if (![category isEqualToString:input]) {
        [additionalObjects addObject: category];
    }
}

[_pickerDataCategory addObjectsFromArray: additionalObjects];

Answer 2

问题是您在迭代时尝试向数组中添加值，将数据保存在其他数组中，然后将其添加到您的 _pickerDataCategory

Answer 3

代码将是这样的：- 在枚举时

    - (IBAction)addNewCategory:(id)sender {
    __block bool isNotExist = false;
       UIAlertController * alertController = [UIAlertController alertControllerWithTitle: @"Add new category"
                                                                              message: @"Please write a new category"
                                                                       preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
        textField.placeholder = @"Category";
        textField.textColor = [UIColor blueColor];
        textField.clearButtonMode = UITextFieldViewModeWhileEditing;
        textField.borderStyle = UITextBorderStyleRoundedRect;
    }];
UIAlertAction *cancel = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
    [alertController dismissViewControllerAnimated:YES completion:nil];
}];

UIAlertAction *ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
    NSString *input = alertController.textFields[0].text;
    //Check if the category exist already
    NSMutableArray * arrTemp = _pickerDataCategory;
    for (NSString *category in arrTemp)
    {
        if ([category isEqualToString:input])
        {
             [self popupMessage:@"Category already exists" title:@"Error"];
            isNotExist = false;
            return;
        }else{
            NSString *msg = [@"Category has been added : " stringByAppendingString:input];
             [self popupMessage:msg title:@"Ok"];
            isNotExist = true;


            [_pickerDataCategory addObject:input];//CRASH
            [_picker_cateogry reloadAllComponents];

        }
    }



}];

[alertController addAction:cancel];
[alertController addAction:ok];

[self presentViewController:alertController animated:YES completion:nil];

  }

将 NSString 添加到 NSMutableArray 崩溃

Add NSString to NSMutableArray crash

arrays

objective-c

nsmutablearray

ipad

ios