Swift iOS : plist

plist

plist是一个XML的子集，使用UTF-8编码的文本文件，它的根节点是一个字典，内容由多个主键和值构成。常常用来存储App的配置信息。

可以直接使用NSDictionary类直接存储它的内容到plist内，比如这样：

import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window : UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow()
        window!.rootViewController = Page()
        window!.rootViewController!.view.backgroundColor = .blue
        window!.makeKeyAndVisible()
        return true
    }
}
class Page: UIViewController {
    let filename = "/profile.plist"
    let data:[String:String] = ["key1" : "value1", "key2":"value2", "key3":"value3"]
    override func viewDidLoad() {
        super.viewDidLoad()
        bar()
    }
    func bar(){
        do {
            let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
            let path = "\(documentDirectory)/\(filename)"
            print(path)
            let dict = NSDictionary(dictionary: data)
            let isWritten = dict.write(toFile: path, atomically: true)
            let dict1 = NSDictionary(contentsOfFile: path)
            print(dict1)
            print("file created: \(isWritten)")
            let text = try String(contentsOfFile: path, encoding: String.Encoding.utf8)
            print(text)
        }catch {print("\(error)")}

    }
}

类NSDictionary的方法write可以指定文件名，然后写入到指定文件。初始化方法 NSDictionary(contentsOfFile:)可以读取plist到词典对象内。

因为plist是UTF-8编码的文本文件，所以，可以使用String打开此文件，输出内容如下（去掉主题无关的文件头后）：

<plist version="1.0">
<dict>
    <key>key1</key>
    <string>value1</string>
    <key>key2</key>
    <string>value2</string>
    <key>key3</key>
    <string>value3</string>
</dict>
</plist>

作为键值对的值，不仅仅可是是字符串，还可以是数字、日期、数组和词典。如下案例展示了plist存储的更多可能性：

import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window : UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow()
        window!.rootViewController = Page()
        window!.rootViewController!.view.backgroundColor = .blue
        window!.makeKeyAndVisible()
        return true
    }
}
class Page: UIViewController {
    let filename = "/profile.plist"
    let data:[String:Any] = ["key1" : "value1", "key2":["key11":"value11"], "key3":[1,"2",NSDate(),3.1]]
    override func viewDidLoad() {
        super.viewDidLoad()
        bar()
    }
    func bar(){
        do {
            let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
            let path = "\(documentDirectory)/\(filename)"
            print(path)
            let dict = NSDictionary(dictionary: data)
            let isWritten = dict.write(toFile: path, atomically: true)
            let dict1 = NSDictionary(contentsOfFile: path)
            print(dict1)
            print("file created: \(isWritten)")
            let text = try String(contentsOfFile: path, encoding: String.Encoding.utf8)
            print(text)
        }catch {print("\(error)")}
    }
}

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