通过Swift将Codable用于归档

Question

我正试着用could在一个iOS应用中保存一些来自textFields的数据，但是当我定义归档函数时，xcode告诉我“泛型参数‘值’无法被推断”。

我正在学习归档，如果有人能帮我，我会很高兴的。

这是我正在使用的代码

class ProfileViewController: UITableViewController {
    var currentProfile: Profile?
    @IBOutlet weak var name: UITextField!
    @IBOutlet weak var surname: UITextField!

    @IBAction func saveProfileButton(_ sender: Any) {
        addCurrentProfile()
        saveProfile()
    }

    func addCurrentProfile(){
        currentProfile?.name = name.text ?? ""
        currentProfile?.surname = surname.text ?? ""
    }

    struct Profile {
        var name: String
        var surname: String

        enum CodingKeys: String, CodingKey {
            case name
            case surname

        }

        init(name:String, surname:String) {
            self.name = name
            self.surname = surname
        }

        func encode(to encoder: Encoder) throws {
            var container = encoder.container(keyedBy: CodingKeys.self)
            try container.encode(name, forKey: .name)
            try container.encode(surname, forKey: .surname)

        }

        init(from decoder: Decoder) throws {
            let container = try decoder.container(keyedBy: CodingKeys.self)
            name = try container.decode(String.self, forKey: .name)
            surname = try container.decode(String.self, forKey: .surname)
        }
    }

    func saveProfile() {
        do {
            let data = try PropertyListEncoder().encode(currentProfile)
            let success = NSKeyedArchiver.archiveRootObject(data, toFile: profile_data.path)
            print(success ? "Successful save" : "Save Failed")
        } catch {
            print("Save Failed")
        }
    }
}

Answer 1

第一件事是让你的结构符合Codable协议，比如：

struct Profile:Codable {
        var name: String
        var surname: String

        enum CodingKeys: String, CodingKey {
            case name
            case surname

        }

        init(name:String, surname:String) {
            self.name = name
            self.surname = surname
        }

        func encode(to encoder: Encoder) throws {
            var container = encoder.container(keyedBy: CodingKeys.self)
            try container.encode(name, forKey: .name)
            try container.encode(surname, forKey: .surname)

        }

        init(from decoder: Decoder) throws {
            let container = try decoder.container(keyedBy: CodingKeys.self)
            name = try container.decode(String.self, forKey: .name)
            surname = try container.decode(String.self, forKey: .surname)
        }
    }

然后，您可以使用PropertyListEncoder实现该目标，如下所示：

func saveProfile() {
        do {
            let data = try PropertyListEncoder().encode(currentProfile)
            let success = NSKeyedArchiver.archiveRootObject(data, toFile: profile_data.path)
            print(success ? "Successful save" : "Save Failed")
        } catch {
            print("Save Failed")
        }
    }

Answer 2

这里似乎有几个问题。直接回答您的问题：“无法推断泛型参数'Value‘”。is:您忘记添加协议：

 struct Profile: Codable {
...}