延迟加载变量错误 [英] Lazy loading variable error

问题描述

我正在编写一个涉及核心数据的程序。我为我的上下文和实体创建了类变量，并且我的代码写成这样：

I am writing a program that involves core data. I created a class variable for my context and entity and have my code written like this:

class PersistencyManager {

    var context : NSManagedObjectContext{
        let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
        let localContext = appDelegate.managedObjectContext
        return localContext
    }
    var userEntity : NSEntityDescription {
        let entity = NSEntityDescription.entityForName(EntityNames.User, inManagedObjectContext: context)
        return entity!

    }  
    struct EntityNames {
        private static let User = "User"
        private static let Category = "Category"
    }
}

到目前为止，一切都很好，但我想做的是 em>ly load userEntity

Everything so far works fine, But what I want to do is to "lazy"ly load userEntity

像这样：

   lazy var userEntity : NSEntityDescription = {
        let entity = NSEntityDescription.entityForName(EntityNames.User, inManagedObjectContext: context)
        return entity!

    }()

但是当我这样做时， 实例成员上下文不能用于类型Persistency Manager

But when I do, I get an error: "Instance member 'context' cannot be used on type 'Persistency Manager' "

？如何实现我的目标？

What am I doing wrong? How can I achieve my goal?

谢谢！

推荐答案

请尝试 let entity = NSEntityDescription.entityForName（EntityNames.User，inManagedObjectContext：self.context）

使用 self.context 而不是只是上下文。这在我的操场上。

Note I'm using self.context instead of just context. This builds for me in a playground.

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