使用Swift将类中的struct保存到NSUserDefaults [英] Save struct in class to NSUserDefaults using Swift

问题描述

我有一个类，在类中是基于全局结构的（swift）数组。
我想将这个类的数组保存到NSUserDefaults。这是我的代码：

I have a class and inside the class is a (swift) array, based on a global struct. I want to save an array with this class to NSUserDefaults. This is my code:

struct mystruct {
    var start : NSDate = NSDate()
    var stop : NSDate = NSDate()
}

class MyClass : NSObject {

    var mystructs : [mystruct]

    init(mystructs : [mystruct]) {

        self.mystructs = mystructs 
        super.init()
    }

    func encodeWithCoder(encoder: NSCoder) {
        //let val = mystructs.map { $0 as NSObject } //this also doesn't work
        let objctvtmrec = NSMutableArray(mystructs)  //gives error
        encoder.encodeObject(objctvtmrec)
        //first approach:
        encoder.encodeObject(mystructs) //error: [mystructs] doesn't conform to protocol 'anyobject'
    }

}

var records : [MyClass] {
    get {
        var returnValue : [MyClass]? = NSUserDefaults.standardUserDefaults().objectForKey("records") as? [MyClass]
        if returnValue == nil
        {
            returnValue = []
        }
        return returnValue!
    }
    set (newValue) {
        let val = newValue.map { $0 as AnyObject }
        NSUserDefaults.standardUserDefaults().setObject(val, forKey: "records")
        NSUserDefaults.standardUserDefaults().synchronize()
    }
}

我已经子类化为NSObject，我知道我需要NSCoding。但我没有找到任何方法将struct数组转换为NSMuteableArray或类似的东西我可以存储。直到现在唯一的想法是遍历每个条目并将其直接复制到新数组或在整个项目中使用大量或客观的代码，因此我永远不需要从swift数组转换为objective-c数组。两者都是我不想做的事情。

I already subclassed to NSObject, and I know I need NSCoding. But I don't find any way to convert the struct array to an NSMuteableArray or something similar I can store. The only idea until now is to go through each entry and copy it directly to a new array or to use much or objective-c code all over the project, so i never need to convert from swift arrays to objective-c arrays. Both are things I don't want to do.

推荐答案

Swift结构不是类，因此它们不符合 AnyObject 协议。你必须重新思考你的方法。以下是一些建议：

Swift structs are not classes, therefore they don't conform to AnyObject protocol. You have to rethink your approach. Here are some suggestions:

1. 将 struct 转换为 final class 强制执行不变性

1. Convert your struct to final class to enforce immutability

final class MyStruct {
    let start : NSDate = NSDate()
    let stop : NSDate = NSDate()
}

encoder.encodeObject(mystructs)

将它们映射为类型为的数组字典[String：NSDate]

let structDicts = mystructs.map { ["start": $0.start, "stop": $0.stop] }
encoder.encodeObject(structDicts)

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