为什么我的核心数据保存缓慢？

Question

每次我尝试保存我的NSManagedObjectContex 时，每次都需要 1-8 秒。这是我的代码：

- (IBAction)save
{    
    if (self.managedObjectContext == nil) {
        self.managedObjectContext = [(RootAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
    }

    if (self.brandText.text.length == 0 || self.modelText.text.length == 0) {
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"Error" message:@"Please fill out the required fields" delegate:self cancelButtonTitle:@"Dismiss" otherButtonTitles:nil, nil];
        UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(125, 40, 31, 7)];

        NSString *path = [[NSString alloc] initWithString:[[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"bullet.png"]];
        UIImage *bkgImg = [[UIImage alloc] initWithContentsOfFile:path];
        [imageView setImage:bkgImg];

        [alertView addSubview:imageView];

        [alertView show];

    } else {
        Hand *a = [NSEntityDescription insertNewObjectForEntityForName:@"Hand" inManagedObjectContext:self.managedObjectContext];
        a.brand = self.brandText.text;
        a.caliber = self.cText.text;
        self.managedObjectContext = self.app.managedObjectContext;
        a.notes = self.notesView.text;
        a.serialNumber = self.serialNumberText.text;
        a.nickname = self.nicknameText.text;
        a.model = self.modelText.text;
        a.gunImage = self.image.image;
        a.roundsFired = [NSString stringWithFormat:@"0"];
        a.cleanRounds = [NSString stringWithFormat:@"500"];
        a.showBadge = [NSNumber numberWithBool:YES];
        [self dismissViewControllerAnimated:YES completion:nil];

        NSError *error;     
        if (![self.managedObjectContext save:&error]) {
            UIAlertView *errorAlert = [[UIAlertView alloc]initWithTitle:@"Error" message:@"There was an internal error. \n Please restart the app and try again, Thank You" delegate:self cancelButtonTitle:@"Dismiss" otherButtonTitles:nil, nil];
            [errorAlert show];
        }
    }
}

代码只是保存了所有的 textFields 文本。它这么慢的原因是什么？非常感谢任何帮助。

Answer 1

根据您的问题很难理解发生了什么，但我将修改else 语句如下...

else {
    Hand *a = [NSEntityDescription insertNewObjectForEntityForName:@"Hand" inManagedObjectContext:self.managedObjectContext];
    a.brand = self.brandText.text;
    a.caliber = self.cText.text;
    // why this?
    // self.managedObjectContext = self.app.managedObjectContext;
    a.notes = self.notesView.text;
    a.serialNumber = self.serialNumberText.text;
    a.nickname = self.nicknameText.text;
    a.model = self.modelText.text;
    a.gunImage = self.image.image;
    a.roundsFired = [NSString stringWithFormat:@"0"];
    a.cleanRounds = [NSString stringWithFormat:@"500"];
    a.showBadge = [NSNumber numberWithBool:YES];        

    NSError *error;     
    if (![self.managedObjectContext save:&error]) { // error during saving
        UIAlertView *errorAlert = [[UIAlertView alloc]initWithTitle:@"Error" message:@"There was an internal error. \n Please restart the app and try again, Thank You" delegate:self cancelButtonTitle:@"Dismiss" otherButtonTitles:nil, nil];
        [errorAlert show];
    } else { // the save completes correctly, dismiss the view controller
        [self dismissViewControllerAnimated:YES completion:nil];
    }
}

如果你想监控 Core Data，你应该通过 Instrument 来完成。此外，您可以按如下方式设置 Xcode：XCode4 and Core Data: How to enable SQL Debugging。

编辑

由于图像保存缓慢（根据您的评论），您应该依赖这些规则。

Core Data - Storing Images (iPhone)

编辑 2

好的，因为您事先不知道图像的大小（以字节为单位），所以我真的建议将图像存储在文件系统中，而不是存储在核心数据存储中。在数据库中只保存图像的路径。图像将保存在背景中。这是为了防止 UI 被阻塞。

否则，如果 iOS 5 是最低要求，请使用外部存储标志。 How to enable External Storage for Binary Data in Core Data

希望对您有所帮助。