通过 XCode 7.1.1、Swift 2.1 和 iOS 9
测试
你有几个选项来保存你的自定义对象（数组）：
-
NSUserDefaults：存储应用设置、偏好、用户默认值 :-)
-
NSKeyedArchiver：用于一般数据存储
- 核心数据：用于更复杂的数据存储（类似数据库）
我将核心数据排除在讨论之外，但想向您展示为什么您应该更好地使用 NSKeyedArchiver 而不是 NSUserdefaults。
我已经更新了您的 Player 类并为这两个选项提供了方法。虽然这两个选项都有效，但如果您比较“加载和保存”方法，您会发现 NSKeydArchiver 需要更少的代码来处理自定义对象数组。此外，使用 NSKeyedArchiver，您可以轻松地将内容存储到单独的文件中，而无需担心每个属性的唯一“键”名称。
import UIKit
import Foundation
// a custom class like the one that you want to archive needs to conform to NSCoding, so it can encode and decode itself and its properties when it's asked for by the archiver (NSKeydedArchiver or NSUserDefaults)
// because of that, the class also needs to subclass NSObject
class Player: NSObject, NSCoding {
var name: String = ""
// designated initializer
init(name: String) {
print("designated initializer")
self.name = name
super.init()
}
// MARK: - Conform to NSCoding
func encodeWithCoder(aCoder: NSCoder) {
print("encodeWithCoder")
aCoder.encodeObject(name, forKey: "name")
}
// since we inherit from NSObject, we're not a final class -> therefore this initializer must be declared as 'required'
// it also must be declared as a 'convenience' initializer, because we still have a designated initializer as well
required convenience init?(coder aDecoder: NSCoder) {
print("decodeWithCoder")
guard let unarchivedName = aDecoder.decodeObjectForKey("name") as? String
else {
return nil
}
// now (we must) call the designated initializer
self.init(name: unarchivedName)
}
// MARK: - Archiving & Unarchiving using NSUserDefaults
class func savePlayersToUserDefaults(players: [Player]) {
// first we need to convert our array of custom Player objects to a NSData blob, as NSUserDefaults cannot handle arrays of custom objects. It is limited to NSString, NSNumber, NSDate, NSArray, NSData. There are also some convenience methods like setBool, setInteger, ... but of course no convenience method for a custom object
// note that NSKeyedArchiver will iterate over the 'players' array. So 'encodeWithCoder' will be called for each object in the array (see the print statements)
let dataBlob = NSKeyedArchiver.archivedDataWithRootObject(players)
// now we store the NSData blob in the user defaults
NSUserDefaults.standardUserDefaults().setObject(dataBlob, forKey: "PlayersInUserDefaults")
// make sure we save/sync before loading again
NSUserDefaults.standardUserDefaults().synchronize()
}
class func loadPlayersFromUserDefaults() -> [Player]? {
// now do everything in reverse :
//
// - first get the NSData blob back from the user defaults.
// - then try to convert it to an NSData blob (this is the 'as? NSData' part in the first guard statement)
// - then use the NSKeydedUnarchiver to decode each custom object in the NSData array. This again will generate a call to 'init?(coder aDecoder)' for each element in the array
// - and when that succeeded try to convert this [NSData] array to an [Player]
guard let decodedNSDataBlob = NSUserDefaults.standardUserDefaults().objectForKey("PlayersInUserDefaults") as? NSData,
let loadedPlayersFromUserDefault = NSKeyedUnarchiver.unarchiveObjectWithData(decodedNSDataBlob) as? [Player]
else {
return nil
}
return loadedPlayersFromUserDefault
}
// MARK: - Archivig & Unarchiving using a regular file (using NSKeyedUnarchiver)
private class func getFileURL() -> NSURL {
// construct a URL for a file named 'Players' in the DocumentDirectory
let documentsDirectory = NSFileManager().URLsForDirectory((.DocumentDirectory), inDomains: .UserDomainMask).first!
let archiveURL = documentsDirectory.URLByAppendingPathComponent("Players")
return archiveURL
}
class func savePlayersToDisk(players: [Player]) {
let success = NSKeyedArchiver.archiveRootObject(players, toFile: Player.getFileURL().path!)
if !success {
print("failed to save") // you could return the error here to the caller
}
}
class func loadPlayersFromDisk() -> [Player]? {
return NSKeyedUnarchiver.unarchiveObjectWithFile(Player.getFileURL().path!) as? [Player]
}
}
我已经对这个类进行了如下测试（单视图应用，在ViewController的viewDidLoad方法中）
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// create some data
let player1 = Player(name: "John")
let player2 = Player(name: "Patrick")
let playersArray = [player1, player2]
print("--- NSUserDefaults demo ---")
Player.savePlayersToUserDefaults(playersArray)
if let retreivedPlayers = Player.loadPlayersFromUserDefaults() {
print("loaded \(retreivedPlayers.count) players from NSUserDefaults")
print("\(retreivedPlayers[0].name)")
print("\(retreivedPlayers[1].name)")
} else {
print("failed")
}
print("--- file demo ---")
Player.savePlayersToDisk(playersArray)
if let retreivedPlayers = Player.loadPlayersFromDisk() {
print("loaded \(retreivedPlayers.count) players from disk")
print("\(retreivedPlayers[0].name)")
print("\(retreivedPlayers[1].name)")
} else {
print("failed")
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
如上所述，两种方法产生相同的结果
此外，在现实生活中的应用程序中，您可以更好地处理错误，因为归档和取消归档可能会失败。