我在Playground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Person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userDefaults
let userDefaults: UserDefaults = UserDefaults.standard()
userDefaults.set(encodedData, forKey: "people")
userDefaults.synchronize()
检查
print("saved object: \(userDefaults.object(forKey: "people"))")
从userDefaults
转发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：在解包可选值时意外发现nil”。 “检查”行还显示保存的对象为零。这是我对象的NSCoder中的错误吗？
答案 0 :(得分：88)
Swift 4 Note
您可以再次在Playground中保存/测试您的值
Swift 3
UserDefaults需要在真实项目中进行测试。注意：无需强制同步。如果要在操场中测试编码/解码，可以使用键控归档器将数据保存到文档目录中的plist文件中。您还需要修复课程中的一些问题：
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")
}
}
}
答案 1 :(得分：49)
FROM 8.0-jre8-alpine
COPY myapp.war /usr/local/tomcat/webapps/myapp.war
Swift 3已经改变了;这不再适用于价值类型。现在正确的语法是：
let age = aDecoder.decodeObject(forKey: "age") as! Int
有各种不同类型的相关解码...（）函数：
let age = aDecoder.decodeInteger(forKey: "age")
修改：Full list of all possible decodeXXX functions in Swift 3
编辑：
另一个重要注意事项：如果您之前保存的数据是使用较早版本的Swift编码的，那么必须必须使用decodeObject（）解析，然后使用encode（...）对数据进行重新编码如果它是值类型，则无法再使用decodeObject（）对其进行解码。因此，Markus Wyss的答案将允许您处理使用Swift版本编码数据的情况：
let myBool = aDecoder.decodeBoolean(forKey: "myStoredBool")
let myFloat = aDecoder.decodeFloat(forKey: "myStoredFloat")
答案 2 :(得分：11)
试试这个：
self.age = aDecoder.decodeObject(forKey: "age") as? Int ?? aDecoder.decodeInteger(forKey: "age")
答案 3 :(得分：2)
在Swift 4中：
您可以使用Codable从Userdefaults中保存和检索自定义对象。如果您经常这样做，则可以添加为扩展名，并按如下所示使用它。
var app = {
// Url/Path to the augmented reality experience you would like to load
arExperienceUrl: "www/index.html",
// The features your augmented reality experience requires, only define the ones you really need
requiredFeatures: [ "image_tracking"],
// Represents the device capability of launching augmented reality experiences with specific features
isDeviceSupported: false,
// Additional startup settings, for now the only setting available is camera_position (back|front)
startupConfiguration:
{
"camera_position": "back"
},
// Application Constructor
initialize: function() {
this.bindEvents();
},
// Bind Event Listeners
//
// Bind any events that are required on startup. Common events are:
// 'load', 'deviceready', 'offline', and 'online'.
bindEvents: function() {
document.addEventListener('deviceready', this.onDeviceReady, false);
},
// deviceready Event Handler
onDeviceReady: function() {
app.wikitudePlugin = cordova.require("com.wikitude.phonegap.WikitudePlugin.WikitudePlugin");
app.wikitudePlugin.isDeviceSupported(app.onDeviceSupported, app.onDeviceNotSupported, app.requiredFeatures);
},
// Callback if the device supports all required features
onDeviceSupported: function() {
app.wikitudePlugin.loadARchitectWorld(
app.onARExperienceLoadedSuccessful,
app.onARExperienceLoadError,
app.arExperienceUrl,
app.requiredFeatures,
app.startupConfiguration
);
},
// Callback if the device does not support all required features
onDeviceNotSupported: function(errorMessage) {
alert("Device not supported"+ errorMessage);
},
// Callback if your AR experience loaded successful
onARExperienceLoadedSuccessful: function(loadedURL) {
/* Respond to successful augmented reality experience loading if you need to */
alert(AR);
},
// Callback if your AR experience did not load successful
onARExperienceLoadError: function(errorMessage) {
alert(errorMessage);
}
};
app.initialize();
您的课程必须遵循Codable。它只是可编码和可解码协议的一种类型。
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
}
}
}
用法：
class UpdateProfile: Codable {
//Your stuffs
}
有关更多编码和解码自定义类型，请通过Apple's documentation进行操作。
答案 4 :(得分：1)
在UserDefaults中保存“自定义对象”的简单示例如下：
您无需借助THE GREAT'CODABLE'编写用于保存/检索对象的样板代码，这就是您摆脱烦人的手动编码/解码的目的 < / p>
因此，如果您已经在使用NSCoding并切换到Codable（可编码+可分解的组合）协议，请从代码中删除以下两种方法
required init(coder decoder: NSCoder) // NOT REQUIRED ANY MORE, DECODABLE TAKES CARE OF IT
func encode(with coder: NSCoder) // NOT REQUIRED ANY MORE, ENCODABLE TAKES CARE OF IT
让我们从Codable的简单性开始吧...
创建要存储在UserDefaults中的自定义类或结构
struct Person : Codable {
var name:String
}
OR
class Person : Codable {
var name:String
init(name:String) {
self.name = name
}
}
按如下所示在UserDefaults中保存对象
if let encoded = try? JSONEncoder().encode(Person(name: "Dhaval")) {
UserDefaults.standard.set(encoded, forKey: "kSavedPerson")
}
从UserDefaults中加载对象，如下所示：
guard let savedPersonData = UserDefaults.standard.object(forKey: "kSavedPerson") as? Data else { return }
guard let savedPerson = try? JSONDecoder().decode(Person.self, from: savedPersonData) else { return }
print("\n Saved person name : \(savedPerson.name)")
就这样...
保存/加载过程中很高兴..：）
答案 5 :(得分：1)
在Swift 5中，我将使用属性包装器来简化代码：
/// A type that adds an interface to use the user’s defaults with codable types
///
/// Example:
/// ```
/// @UserDefaultCodable(key: "nameKey", defaultValue: "Root") var name: String
/// ```
/// Adding the attribute @UserDefaultCodable the property works reading and writing from user's defaults
/// with any codable type
///
@propertyWrapper public struct UserDefaultCodable<T: Codable> {
private let key: String
private let defaultValue: T
/// Initialize the key and the default value.
public init(key: String, defaultValue: T) {
self.key = key
self.defaultValue = defaultValue
}
public var wrappedValue: T {
get {
// Read value from UserDefaults
guard let data = UserDefaults.standard.object(forKey: key) as? Data else {
// Return defaultValue when no data in UserDefaults
return defaultValue
}
// Convert data to the desire data type
let value = try? JSONDecoder().decode(T.self, from: data)
return value ?? defaultValue
}
set {
// Convert newValue to data
let data = try? JSONEncoder().encode(newValue)
// Set value to UserDefaults
UserDefaults.standard.set(data, forKey: key)
}
}
}