如何将字典词典保存为UserDefaults [Int:[Int:Int]]?

问题描述

我正在尝试将词典词典保存到UserDefaults.

I am trying to save a dictionary of dictionaries to UserDefaults.

我可以这样保存字典:

var dict = [Int:[Int:Int]]()
dict[1] = [4:3]
dict[10] = [5:10]

let data = try
NSKeyedArchiver.archivedData(withRootObject: dict, requiringSecureCoding: false)
UserDefaults.standard.set(data, forKey: "dict")

但是当我尝试检索它时:

But when I try to retrieve it:

if let data2 = defaults.object(forKey: "dict") as? NSData {
let dict = NSKeyedUnarchiver.unarchivedObject(ofClasses: [Int:[Int:Int]], from: data2)
print(dict)
}

我得到一个错误:无法将类型'[Int:[Int:Int]].Type'的值转换为预期的参数类型'[AnyClass]'(aka'Array')

I get an error: Cannot convert value of type '[Int : [Int : Int]].Type' to expected argument type '[AnyClass]' (aka 'Array')

是否可以在UserDefaults中存储[Int:[Int:Int]]字典?还是我必须使用其他方法?

Is there a way to store a [Int:[Int:Int]] Dictionary in UserDefaults? Or I have to use other aproach?

推荐答案

您可以简单地使用JSONEncoder和JSONDecoder进行编码，因为Dictionary<Int,Dictionary<Int,Int>>符合Codable.

You can simply use JSONEncoder and JSONDecoder to do the encoding, since Dictionary<Int,Dictionary<Int,Int>> conforms to Codable.

var dict = [Int:[Int:Int]]()
dict[1] = [4:3]
dict[10] = [5:10]

let encodedDict = try! JSONEncoder().encode(dict)

UserDefaults.standard.set(encodedDict, forKey: "dict")
let decodedDict = try! JSONDecoder().decode([Int:[Int:Int]].self, from: UserDefaults.standard.data(forKey: "dict")!) //[10: [5: 10], 1: [4: 3]]

在处理实数值而不是这些硬编码的数值时，请勿使用强制展开.

Don't use force unwrapping when working with real values rather than these hard coded ones.

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