Decode an Array of an custom struct in Swift out of the UserDefaults

Question

I want to encode an Array of my own struct, which I want to save in UserDefaults, and then read It out (after decoding it). I know how to code the first part (following), that means how to encode an array and save it in Userdefaults.

struct mystruct: Codable {
var int: Int
var string: String
}

var array = [mystruct(int: 2, string: "Example"), mystruct(int: 5, string: "Other Example")]

var encodedArray = try JSONEncoder().encode(array)

UserDefaults.standard.set(encodedArray, forKey: "array")

I also know how to get the data back from the Userdefaults:

var newArray = UserDefaults.standard.data(forKey: "array")

But I don't know how to decode an whole array...

Does this answer your question? How to manually decode an an array in swift 4 Codable? — gcharita
– gcharita, Commented Apr 7, 2021 at 22:34

Leo Dabus · Accepted Answer · 2021-04-07 22:39:31Z

2

You just need to pass your custom structure array type [MyStruct].self to the JSONDecoder:

struct MyStruct: Codable {
    let int: Int
    let string: String
}

let myStructures: [MyStruct] = [.init(int: 2, string: "Example"),
                         .init(int: 5, string: "Other Example")]

do {
    let encodedData = try JSONEncoder().encode(myStructures)
    UserDefaults.standard.set(encodedData, forKey: "array")
    if let decodedData = UserDefaults.standard.data(forKey: "array") {
        let decodedArray = try JSONDecoder().decode([MyStruct].self, from: decodedData)
        print(decodedArray)
    }
} catch {
    print(error)
}

This will print:

[MyStruct(int: 2, string: "Example"), MyStruct(int: 5, string: "Other Example")]

answered Apr 7, 2021 at 22:39

Leo Dabus

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