我得到了一个空结果。
AppDelegate.h
AppDelegate.h
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
AppDelegate.m
@synthesize managedObjectContext = __managedObjectContext;
@synthesize managedObjectModel = __managedObjectModel;
@synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
Person *newPerson = [NSEntityDescription
insertNewObjectForEntityForName:@"Person"
inManagedObjectContext:self.managedObjectContext];
.......
}
我有一个xcdatamodeld文件,其中有一个名为Person的实体和一个名为name的属性。我从NSManagedObject创建了一个Person.h和.m文件。
为什么我的输出结果为null?
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Person''
assert(self.managedObjectContext);
- Daij-DjanNSLog(@"%@", self.managedObjectModel.entitiesByName);
- Daij-Djan