尝试保存核心数据记录后出现错误

问题描述

我有一个视图控制器来添加核心数据记录。核心数据实体名称为FavoriteThings，属性为Thingname。我有一个名为SaveButtonAction的保存按钮动作。当我点击按钮内部时，应该存储在文本字段ToDoTextField中插入的文本，但是应用程序崩溃了，并显示以下日志错误：

  2013-12-09 12：30：07.488最喜欢的事情[1701：a0b] ***由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：'+ entityForName：nil不是合法的NSManagedObjectContext参数，用于搜索实体名称' 
  

这是该方法的代码

 -（IBAction）SaveButtonAction：（id）sender {
 FavoriteThing * newEntry = [NSEntityDescription insertNewObjectForEntityForName：@ FavoriteThing inManagedObjectContext：managedObjectContext]; 
 newEntry.thingName = self.ToDoTextField.text; 
 NSError *错误; 
 if（！[self.managedObjectContext save：& error]）
 {
 NSLog（@糟糕，无法保存：％@，[错误localizedDescription]）; 
} 
  

谢谢您的时间。.

解决方案

请检查实体名称，并在YourAppDeleagte.h

$

中执行以下操作b
$ b

  +（YourAppDeleagte *）sharedManagedContext; 
  

在YourAppDeleagte.m

  +（YourAppDeleagte *）sharedManagedContext {
 
 return（YourAppDeleagte *）[[UIApplication sharedApplication] delegate]; 
} 
  

在viewController.m中

#import YourAppDelegate.h

  @property（nonatomic，retain）NSmanagedObjectContext * managedObjectContext; 
 
-（void）viewDidLoad {
 [super viewDidLoad]; 
 self.managedObjectContext = [YourAppDelagete shareManagedContext] .managedObjectContext; 
} 
  

i have a view controller to add a core data record. The core data entity name is FavoriteThings, the attribute is thingname. I have a save button action called SaveButtonAction. When I tap inside the button, the text inserted in the textfield called ToDoTextField should be stored, but the app crashed showing following log error:

2013-12-09 12:30:07.488 Favorite Things[1701:a0b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'FavoriteThing''

This is the code for the method

- (IBAction)SaveButtonAction:(id)sender {
    FavoriteThing *newEntry = [NSEntityDescription insertNewObjectForEntityForName:@"FavoriteThing" inManagedObjectContext:managedObjectContext ];
    newEntry.thingName = self.ToDoTextField.text;
    NSError *error;
    if (![self.managedObjectContext save:&error])
    {
        NSLog(@"Whoops, couldn't save:%@",[error localizedDescription]);
    }

Thank you for your time..

解决方案

Please check the enity name and also do the following

in YourAppDeleagte.h

+(YourAppDeleagte*)sharedManagedContext;

in YourAppDeleagte.m

  +(YourAppDeleagte*)sharedManagedContext{

     return (YourAppDeleagte *)[[UIApplication sharedApplication]delegate];
}

in viewController.m

#import "YourAppDelegate.h"

@property(nonatomic,retain)NSmanagedObjectContext *managedObjectContext;

-(void)viewDidLoad{
   [super viewDidLoad];
   self.managedObjectContext=[YourAppDelagete shareManagedContext].managedObjectContext;
 }

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