Question

我知道错误发生在这一行，因为应用程序可以正常使用此行注释掉：

controller.managedObjectContext = self.managedObjectContext;

错误是：

由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：' - [UITableViewController setManagedObjectContext：]：无法识别的选择器发送到实例0x7490da0'

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

这意味着当你这样做时：

controller.managedObjectContext = self.managedObjectContext;

controller没有managedObjectContext属性，因此无法为其分配任何内容。您没有发布controller的代码，因此我不确切地知道它的外观，但错误消息显示它是UITableViewController。如果您想以正确的方式解决此问题，则需要为controller提供managedObjectContext属性，以便您可以使此分配工作。

Answer 2

您所要做的就是删除这一行：

controller.managedObjectContext = self.managedObjectContext;

只要您在视图中需要托管对象上下文，请使用：

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

Answer 3

错误表明您正在使用非子类UITableViewController而认为您正在使用具有名为managedObjectContext的属性的子类。检查你的故事板，xib或代码，看看这发生了什么。

因为你正在尝试使用依赖注入（这是一件非常好的事情）然后我会建议你检查创建controller的位置并更改它以便它使用UITableViewController的子类有正确的财产。

- [UITableViewController setManagedObjectContext：]：无法识别的选择器发送到实例0x7490da0'

3 个答案: