我在Playground中使用Swift 3,Xcode 8.0拥有此功能:
import Foundation class Person: NSObject, NSCoding { var name: String var age: Int init(name: String, age: Int) { self.name = name self.age = age } required convenience init(coder aDecoder: NSCoder) { let name = aDecoder.decodeObject(forKey: "name") as! String let age = aDecoder.decodeObject(forKey: "age") as! Int self.init( name: name, age: age ) } func encode(with aCoder: NSCoder) { aCoder.encode(name, forKey: "name") aCoder.encode(age, forKey: "age") } }
创建人员数组
let newPerson = Person(name: "Joe", age: 10) var people = [Person]() people.append(newPerson)
编码数组
let encodedData = NSKeyedArchiver.archivedData(withRootObject: people) print("encodedData: \(encodedData))")
保存到用户默认值
let userDefaults: UserDefaults = UserDefaults.standard() userDefaults.set(encodedData, forKey: "people") userDefaults.synchronize()
检查
print("saved object: \(userDefaults.object(forKey: "people"))")
从userDefaults返回
if let data = userDefaults.object(forKey: "people") { let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: data as! Data) print("myPeopleList: \(myPeopleList)") }else{ print("There is an issue") }
只需检查存档的数据
if let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: encodedData){ print("myPeopleList: \(myPeopleList)") }else{ print("There is an issue") }
我无法正确将数据对象保存到userDefaults,此外,底部的检查还会产生错误“严重错误:在展开可选值时意外发现nil”。“检查”行还显示已保存的对象为nil。这是我对象的NSCoder中的错误吗?
斯威夫特4注意
您可以再次在Playground中保存/测试您的值
迅捷3
UserDefaults需要在真实项目中进行测试。注意:无需强制同步。如果要在运动场中测试编码/解码,则可以使用键控存档器将数据保存到文档目录中的plist文件中。您还需要修复班级中的一些问题:
class Person: NSObject, NSCoding { let name: String let age: Int init(name: String, age: Int) { self.name = name self.age = age } required init(coder decoder: NSCoder) { self.name = decoder.decodeObject(forKey: "name") as? String ?? "" self.age = decoder.decodeInteger(forKey: "age") } func encode(with coder: NSCoder) { coder.encode(name, forKey: "name") coder.encode(age, forKey: "age") } }
测试:
class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() // setting a value for a key let newPerson = Person(name: "Joe", age: 10) var people = [Person]() people.append(newPerson) let encodedData = NSKeyedArchiver.archivedData(withRootObject: people) UserDefaults.standard.set(encodedData, forKey: "people") // retrieving a value for a key if let data = UserDefaults.standard.data(forKey: "people"), let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: data) as? [Person] { myPeopleList.forEach({print( $0.name, $0.age)}) // Joe 10 } else { print("There is an issue") } } }