我有一个实体“用户”和一个属性“名称”。我正在尝试使用 FirstViewController.m 文件中使用的代码为实体“用户”添加一个名称:
- (IBAction)addUser:(id)sender {
User *user = (User *)[NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:managedObjectContext];
[user setName:@"Bhagwan"];
NSError *error = nil;
if (![managedObjectContext save:&error]) {
// Handle the error.
}
}
但它显示错误消息:
由于未捕获的异常“NSInvalidArgumentException”而终止应用程序,原因:“-[UIViewController addUser:]: unrecognized selector sent to instance 0x4d38950”
如何解决这个问题?请帮忙!!
编辑:
#import <UIKit/UIKit.h>
#import "FirstViewController.h"
#import <CoreData/CoreData.h>
@interface CoreDataTry2AppDelegate : NSObject <UIApplicationDelegate> {
UIViewController *_first; } @property (nonatomic, retain) IBOutlet UIViewController *first;
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain, readonly) NSManagedObjectContext
*managedObjectContext; @property (nonatomic, retain, readonly) NSManagedObjectModel
*managedObjectModel; @property (nonatomic, retain, readonly) NSPersistentStoreCoordinator
*persistentStoreCoordinator;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;
@end
这是应用程序委托文件。