Question

目标c中的

无法将我的核心数据与字符串进行比较

- (IBAction)loginBut:(id)sender {
    AppDelegate *appDel = [[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDel managedObjectContext];
    /*NSEntityDescription *newPassword = [NSEntityDescription insertNewObjectForEntityForName:@"Pinpass" inManagedObjectContext:context];
    //[newPassword setValue:@"9090" forKey:@"password"];
    //[context save:nil];
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Pinpass"];
    request.returnsObjectsAsFaults = NO;
    NSArray *result = [context executeFetchRequest:request error:nil];
    NSLog(@"%@", result);*/
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Pinpass"];
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"(password = %@)", loginField.text];
    [request setPredicate:pred];
    NSError *error;
    NSArray *result = [context executeFetchRequest:request error:&error]; ;


    if (result.count > 0){

        //If([[textField text] compare:entity.attribute]==NSOrderedSame) NSLog(@"Correct!");
                if ([[loginField text] isEqual:[result valueForKey:@"password"]])
 {
                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sign in ok"
                                                        message:@"Sign in succsess!!"
                                                        delegate:self
                                                        cancelButtonTitle:@"OK"
                                                        otherButtonTitles:nil];
                                                        [alert show];
        }
        else{ UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sign in ok"
                                                            message:@"Sign in succsess!!"
                                                           delegate:self
                                                  cancelButtonTitle:@"Cancel"
                                                  otherButtonTitles:@"Say Hello",nil];  }

    }

我的代码有问题吗？或者只是对功能的错误使用

Answer 1

if ([[loginField text] isEqual:[result valueForKey:@"password"]])

result是一个数组，因此您需要指定一个索引，然后检查该索引处的值。

例如，上面的行应该是

if ([[loginField text] isEqual:[[result valueForKey:@"password"] lastObject]])

Answer 2

这里有几件事：

您的谓词正在检查属性password等于loginField.text的托管对象，因此根据定义，任何匹配都会自动为正确的密码。
您的result是NSArray。大概你想要将textField文本与该数组中的单个对象进行比较。这样的事情：

if (result.count > 0) { firstResult = [result firstObject]; if ([[loginField text] isEqual:[firstResult valueForKey:@"password"]]) { do stuff... } }

Answer 3

结果数组包含NSManagedObject名称Pinpass。所以你需要从中获取值并进行比较......

if (result.count > 0){
Pinpass *pinObj=[result objectAtIndex:0];

if ([[loginField text] isEqual:[pinObj valueForKey:@"password"]])
 {
 //AlertView
 }
 else
 { 
 //AlertView
 }

}

希望它可以帮助你......！

比较核心数据和字符串

3 个答案: