- [UITableViewController中setManagedObjectContext：]：</p> <pre><code>controller.managedObjectContext = self.managedObjectContext; </code></pre> <p>的錯誤是：：發送到實例0x7490da0'

Question

我知道，在這條線的應用程序時出現錯誤無法識別的選擇這一行註釋掉工作得很好

終止應用程序由於未捕獲的異常 'NSInvalidArgumentException'，原因： ' - [的UITableViewController setManagedObjectContext：]：無法識別的選擇發送到實例0x7490da0'

的fibroMappAppDelegate.h

// 
// fibroMappAppDelegate.h 
// fibromapp 
// 
// Created by jamie mcallister on 09/08/2013. 
// Copyright (c) 2013 Jamie McAllister. All rights reserved. 
// 

#import <UIKit/UIKit.h> 

@interface fibroMappAppDelegate : UIResponder <UIApplicationDelegate> 

@property (strong, nonatomic) UIWindow *window; 

@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext; 
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel; 
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator; 

- (void)saveContext; 
- (NSURL *)applicationDocumentsDirectory; 

@end 

和fibroMappAppDelegate.m

// 
// fibroMappAppDelegate.m 
// fibromapp 
// 
// Created by jamie mcallister on 09/08/2013. 
// Copyright (c) 2013 Jamie McAllister. All rights reserved. 
// 

#import "fibroMappAppDelegate.h" 

#import "fibroMappMasterViewController.h" 

@implementation fibroMappAppDelegate 

@synthesize managedObjectContext = _managedObjectContext; 
@synthesize managedObjectModel = _managedObjectModel; 
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator; 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    // Override point for customization after application launch. 
    UINavigationController *navigationController = (UINavigationController *)self.window.rootViewController; 
    fibroMappMasterViewController *controller = (fibroMappMasterViewController *)navigationController.topViewController; 
    controller.managedObjectContext = self.managedObjectContext; 
    return YES; 
} 

- (void)applicationWillTerminate:(UIApplication *)application 
{ 
    // Saves changes in the application's managed object context before the application terminates. 
    [self saveContext]; 
} 

- (void)saveContext 
{ 
    NSError *error = nil; 
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext; 
    if (managedObjectContext != nil) { 
     if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) { 
      // Replace this implementation with code to handle the error appropriately. 
      // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 
      NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
      abort(); 
     } 
    } 
} 

#pragma mark - Core Data stack 

// Returns the managed object context for the application. 
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application. 
- (NSManagedObjectContext *)managedObjectContext 
{ 
    if (_managedObjectContext != nil) { 
     return _managedObjectContext; 
    } 

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator]; 
    if (coordinator != nil) { 
     _managedObjectContext = [[NSManagedObjectContext alloc] init]; 
     [_managedObjectContext setPersistentStoreCoordinator:coordinator]; 
    } 
    return _managedObjectContext; 
} 

// Returns the managed object model for the application. 
// If the model doesn't already exist, it is created from the application's model. 
- (NSManagedObjectModel *)managedObjectModel 
{ 
    if (_managedObjectModel != nil) { 
     return _managedObjectModel; 
    } 
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"fibromapp" withExtension:@"momd"]; 
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL]; 
    return _managedObjectModel; 
} 

// Returns the persistent store coordinator for the application. 
// If the coordinator doesn't already exist, it is created and the application's store added to it. 
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator 
{ 
    if (_persistentStoreCoordinator != nil) { 
     return _persistentStoreCoordinator; 
    } 

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"fibromapp.sqlite"]; 

    NSError *error = nil; 
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) { 
     /* 
     Replace this implementation with code to handle the error appropriately. 

     abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 

     Typical reasons for an error here include: 
     * The persistent store is not accessible; 
     * The schema for the persistent store is incompatible with current managed object model. 
     Check the error message to determine what the actual problem was. 


     If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory. 

    If you encounter schema incompatibility errors during development, you can reduce their frequency by: 
    * Simply deleting the existing store: 
    [[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil] 

    * Performing automatic lightweight migration by passing the following dictionary as the options parameter: 
    @{NSMigratePersistentStoresAutomaticallyOption:@YES, NSInferMappingModelAutomaticallyOption:@YES} 

    Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details. 

    */ 
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
    abort(); 
}  

return _persistentStoreCoordinator; 
} 

#pragma mark - Application's Documents directory 

// Returns the URL to the application's Documents directory. 
- (NSURL *)applicationDocumentsDirectory 
{ 
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; 
} 

@end 

Answer 1

這是什麼意思是，當你這樣做：

controller.managedObjectContext = self.managedObjectContext; 

的controller沒有managedObjectContext屬性，所以這是不可能的事情分配給它。您沒有發佈controller的代碼，所以我不確切地知道它的樣子，但錯誤消息說這是一個UITableViewController。如果你想以正確的方式解決這個問題，你需要給controller一個managedObjectContext屬性，這樣你才能完成這個任務。

Answer 2

所有你需要做的就是刪除此行：

controller.managedObjectContext = self.managedObjectContext; 

，只要你需要被管理對象上下文在一個視圖中使用：

[(fibroMappAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext]; 

Answer 3

錯誤表明您正在使用非子類型的UITableViewController，並且認爲您正在使用具有名爲managedObjectContext的屬性的子類。檢查你的故事板，xib或代碼，看看發生了什麼。

由於您試圖使用依賴注入（一個很好的東西順便說一句），那麼我會建議您檢查您創建controller的位置，並更改它，使其使用具有正確屬性的UITableViewController的子類。