如果自定義類(lèi)型需要存放到UserDefaults中需要自定義類(lèi)型繼承NSObject以及NSCoding、NSSecureCoding

NSSecureCoding繼承自NSCoding呈昔，只用實(shí)現(xiàn)其中一個(gè)

public protocol NSCoding {
    public func encode(with aCoder: NSCoder)

    public init?(coder aDecoder: NSCoder) // NS_DESIGNATED_INITIALIZER
}

public protocol NSSecureCoding : NSCoding {

    
    // This property must return YES on all classes that allow secure coding. Subclasses of classes that adopt NSSecureCoding and override initWithCoder: must also override this method and return YES.
    // The Secure Coding Guide should be consulted when writing methods that decode data.
    public static var supportsSecureCoding: Bool { get }
}

以下是我自定義的class

class People: NSObject, NSSecureCoding {
    static var supportsSecureCoding: Bool = true
    enum CodeKey: String {
        case nameKey = "name"
        case ageKey = "age"
        case dogKey = "dog"
    }
    
    var name: String = ""
    var age: Int = 0
    var dog: Dog
    
    override init() {
        name = "123"
        age = 1
        dog = Dog(name: "lanbo", age: 2)
    }
    
    func encode(with aCoder: NSCoder) {
        aCoder.encode(name, forKey: CodeKey.nameKey.rawValue)
        aCoder.encode(age, forKey: CodeKey.ageKey.rawValue)
        aCoder.encode((try? JSONEncoder().encode(dog)) ?? Data())
    }
    
    required init?(coder aDecoder: NSCoder) {
        name = aDecoder.decodeObject(forKey: CodeKey.nameKey.rawValue) as? String ?? ""
        age = aDecoder.decodeInteger(forKey: CodeKey.ageKey.rawValue)
        dog = try! JSONDecoder().decode(Dog.self, from: aDecoder.decodeData() ?? Data())
    }
}


struct Dog: Codable {
    var name: String
    var age: Int
}

使用UserDefaults進(jìn)行存取

let albert = People()
let obj = try? NSKeyedArchiver.archivedData(withRootObject: albert, requiringSecureCoding: false)
UserDefaults.standard.set(obj, forKey: "albert")
UserDefaults.standard.synchronize()
if let per = UserDefaults.standard.object(forKey: "albert") as? Data {
    let p = try! NSKeyedUnarchiver.unarchivedObject(ofClass: People.self, from: per)
    print(p?.dog) //Optional(CacheDemo.Dog(name: "lanbo", age: 2))
}
        

單獨(dú)存取struct時(shí)也可以直接用Codable協(xié)議把結(jié)構(gòu)體轉(zhuǎn)化成Data后存儲(chǔ)

let dog = Dog(name: "333", age: 3)
let pp = try? JSONEncoder().encode(dog)
UserDefaults.standard.set(pp, forKey: "dog")
UserDefaults.standard.synchronize()
        
if let d = UserDefaults.standard.object(forKey: "dog") as? Data {
    if let dd = try? JSONDecoder().decode(Dog.self, from: d) {
         print(dd.name) // 333
    }
}

其中NSKeyedUnarchiver.unarchivedObject這個(gè)方法需要實(shí)現(xiàn)NSSecureCoding才能夠使用衩婚，NSCoding應(yīng)該使用NSKeyedUnarchiver.unarchiveObject(with: Data)但是這個(gè)方法在iOS12廢棄了贺拣，應(yīng)該是蘋(píng)果推薦使用NSSecureCoding.

@available(iOS, introduced: 2.0, deprecated: 12.0, message: "Use +unarchivedObjectOfClass:fromData:error: instead")
    open class func unarchiveObject(with data: Data) -> Any?