使用核心数据Swift 3保存数组？ [英] Saving an array with core data Swift 3?

问题描述

我正在尝试将Core Data中的数组保存为属性。 allImages将被分配给[String]。我见过一些人说它可以变形。将其保存到核心数据中的正确解决方案是什么？

解决方案

怎么做我得到它们的引用，所以我可以将转换为 [String]

这实际上是一个好点，因为

然后创建一个扩展并添加一个在 NSArray 和Swift <$ c $之间强制转换的计算属性c>数组输入：

 扩展名CoreDataArrayObj {
 var images：[String] { 
得到{
返回imagesArray为？阵列<字符串> ?? [] 
} 
设置{
 imagesArray = newValue as NSArray 
} 
} 
} 
  

I'm trying to save an array within Core Data as a property. allImages is going to be assigned to a [String]. I've seen some people say to make it transformable. What is the proper solution to saving this into core data?

解决方案

how do I get reference to them so I can change the transformable to [String]

This is actually a good point because the answer I linked too assumed that you were creating your own NSManagedObject subclasses.

It's worth emphasizing that creating/maintaining your own NSManagedObject subclasses by yourself is a perfectly valid option, some might even suggest that it is a preferred option because you get better visibility of any changes overtime if your project is in a repository.

However - last couple of Core Data projects I have been using Xcode to create the subclasses which means you need create another property in an extension.

Here's the general approach that I've been using:

First, in your model file, I name the attribute with the type of object that it represents, in this case an array:

Then create an extension and add a computed property that casts between NSArray and Swift Array type:

extension CoreDataArrayObj {
    var images: [String] {
        get {
            return imagesArray as? Array<String> ?? []
        }
        set {
            imagesArray = newValue as NSArray
        }
    }
}

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