swift - 我应该如何从 UserDefaults 更新对象值？

Question

有如下结构

struct User:Codable {
    static var shared = User()
    var name:String!
    var age:Int!
}

用户可以保存他们的信息

var userInfo = User.shared
userInfo.name = "Kevin"
userInfo.age = 28
UserDefaults.standard.set(try? PropertyListEncoder().encode(userInfo), forKey:"UserInformation")

下面我试过了

但它似乎创建了新对象

UserDefaults.standard.set(try? PropertyListEncoder().encode(userInfo.age == 32), forKey:"UserInformation")

是否可以只从 UserDefault 更新 userInfo 对象？

喜欢只改变userInfo.age = 32

Answer 1

你需要解码对象，改变它的值，然后再编码回来:

guard let data = UserDefaults.standard.data(forKey: "UserInformation") else {
    // no data associated with the key!
}
guard var obj = try? PropertyListDecoder().decode(User.self, from: data) else {
    // something wrong happened with decoding 
}
obj.age = 32 // changing the object...
guard let newData = try? PropertyListEncoder().encode(obj) else {
    // something wrong happened with encoding
}
UserDefaults.standard.set(newData, forKey: "UserInformation")