[IOS] 使用属性列表实现数据持久化

最新推荐文章于 2025-04-26 18:18:36 发布

stary_yan

最新推荐文章于 2025-04-26 18:18:36 发布

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分类专栏： IOS

本文链接：https://blog.youkuaiyun.com/stary_yan/article/details/51059610

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本文介绍了一个使用Swift实现的UIViewController子类，该类能够将界面上的开关状态保存到本地文件并在应用重新激活时恢复这些状态。文章展示了如何利用Swift和UIKit进行iOS应用开发中的数据持久化操作。

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//
//  ViewController.swift
//  just
//
//  Created by Stary on 4/4/16.
//  Copyright © 2016 Stary. All rights reserved.
//

import UIKit

class ViewController: UIViewController {
    // array of switches
    @IBOutlet var Switches : [UISwitch]!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let filePath = self.dataFilePath()
        // judge if the path is available
        if (NSFileManager.defaultManager().fileExistsAtPath(filePath)) {
            let array = NSArray(contentsOfFile: filePath) as! [Bool]
            for var i = 0; i < array.count; i++ {
                Switches[i].on = array[i]
            }
        }

        let app = UIApplication.sharedApplication()
        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "applicationWillResignActive:",
            name: UIApplicationWillResignActiveNotification,
            object: app)
    }
    // receive the message
    // Sent when the application is about to move from active to 
    // interruptions (such as an incoming phone call or SMS message) or when the user quits the application 
    // and it begins the transition to the background state.
    func applicationWillResignActive(notification:NSNotification) {
        let filePath = self.dataFilePath()
        let array = (self.Switches as NSArray).valueForKey("on") as! NSArray
        array.writeToFile(filePath, atomically: true)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // 寻找文件路径
   func dataFilePath() -> String {
    let paths = NSSearchPathForDirectoriesInDomains(
        NSSearchPathDirectory.DocumentDirectory,
        NSSearchPathDomainMask.UserDomainMask, true)
    let documentsDirectory = paths[0] as NSString
    return documentsDirectory.stringByAppendingPathComponent("data.plist") as String
    }

}