我在Playground中使用Swift 3,Xcode 8.0:
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)
对数组进行编码
let encodedData = NSKeyedArchiver.archivedData(withRootObject: people)
print("encodedData: \(encodedData))")
保存到userDefaults
let userDefaults: UserDefaults = UserDefaults.standard()
userDefaults.set(encodedData, forKey: "people")
userDefaults.synchronize()
检查
print("saved object: \(userDefaults.object(forKey: "people"))")
从userDefaults检索
if let data = userDefaults.object(forKey: "people") {
let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: data as! Data)
print("myPeopleList: \(myPeopleList)")
}else{
print("There is an issue")
}
只需检查已存档的数据
if let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: encodedData){
print("myPeopleList: \(myPeopleList)")
}else{
print("There is an issue")
}
我无法正确地将数据对象保存到userDefaults,此外,底部的检查会产生错误:
致命错误:展开可选值时意外发现nil
"check“行还显示保存的对象为nil。这是我的对象的NSCoder中的错误吗?
发布于 2016-06-23 13:29:08
Swift 4或更高版本
您可以再次在游乐场中保存/测试您的值
UserDefaults需要在真实的项目中进行测试。注意:不需要强制同步。如果您想在游乐场中测试编码/解码,可以使用键控归档程序将数据保存到文档目录中的plist文件中。您还需要修复类中的一些问题:
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()
do {
// setting a value for a key
let newPerson = Person(name: "Joe", age: 10)
var people = [Person]()
people.append(newPerson)
let encodedData = try NSKeyedArchiver.archivedData(withRootObject: people, requiringSecureCoding: false)
UserDefaults.standard.set(encodedData, forKey: "people")
// retrieving a value for a key
if let data = UserDefaults.standard.data(forKey: "people"),
let myPeopleList = try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data) as? [Person] {
myPeopleList.forEach({print($0.name, $0.age)}) // Joe 10
}
} catch {
print(error)
}
}
}
发布于 2016-08-30 10:46:12
let age = aDecoder.decodeObject(forKey: "age") as! Int
这在Swift 3中已更改;这不再适用于值类型。正确的语法现在是:
let age = aDecoder.decodeInteger(forKey: "age")
有各种不同类型的相关decode...()函数:
let myBool = aDecoder.decodeBoolean(forKey: "myStoredBool")
let myFloat = aDecoder.decodeFloat(forKey: "myStoredFloat")
编辑:Full list of all possible decodeXXX functions in Swift 3
编辑:
另一个重要的注意事项:如果您以前保存过用旧版本的Swift编码的数据,则必须使用decodeObject()对这些值进行编码,但是一旦您使用(...)对数据进行了重新编码,则必须使用decodeObject()对这些值进行编码如果它是值类型,则不能再使用decodeObject()对其进行解码。因此,Markus Wyss的答案将允许您处理使用以下任一Swift版本对数据进行编码的情况:
self.age = aDecoder.decodeObject(forKey: "age") as? Int ?? aDecoder.decodeInteger(forKey: "age")
发布于 2019-01-03 19:31:43
Swift 4中的:
您可以使用Codable来保存和检索Userdefaults中的自定义对象。如果您经常这样做,那么您可以添加为扩展并使用它,如下所示。
extension UserDefaults {
func save<T:Encodable>(customObject object: T, inKey key: String) {
let encoder = JSONEncoder()
if let encoded = try? encoder.encode(object) {
self.set(encoded, forKey: key)
}
}
func retrieve<T:Decodable>(object type:T.Type, fromKey key: String) -> T? {
if let data = self.data(forKey: key) {
let decoder = JSONDecoder()
if let object = try? decoder.decode(type, from: data) {
return object
}else {
print("Couldnt decode object")
return nil
}
}else {
print("Couldnt find key")
return nil
}
}
}
你的类必须跟在Codable后面。它只是可编码和可解码协议的类型别名。
class UpdateProfile: Codable {
//Your stuffs
}
使用:
let updateProfile = UpdateProfile()
//To save the object
UserDefaults.standard.save(customObject: updateProfile, inKey: "YourKey")
//To retrieve the saved object
let obj = UserDefaults.standard.retrieve(object: UpdateProfile.self, fromKey: "YourKey")
有关更多自定义类型的编码和解码信息,请访问Apple's documentation。
https://stackoverflow.com/questions/37980432
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