读写应用程序数据-NSUserDefault、对象归档（NSKeyedArchiver）、文件操作

ios中数据持久化存储方式一般有5种：NSUserDefault、对象归档（NSKeyedArchiver）、文件操作、数据库存储（SQLite3）、CoreData。

1、NSUserDefault用于保存程序相关的偏好设置和配置数据等，以便下次启动程序后能恢复上次的设置。

NSUserDefault和对象归档

 //通过单利来创建一个NSUserDefaults对象，全局变量NSUserDefault，可在整个项目传递变量
         let userDefault:NSUserDefaults = NSUserDefaults.standardUserDefaults()

         //通过init方法创建
         let userDefault1:NSUserDefaults = NSUserDefaults(suiteName: "SwiftClass")!
         print(userDefault1.dictionaryRepresentation())

         //获取userDefault单利下所有的值
         print(userDefault.dictionaryRepresentation())

         //判断NSUserDefaults的“appMessage”key 在dictionaryRepresentation中是否存在，如果不存在就设置“appMessage”值为This is app message。
         if(userDefault.objectForKey("message") == nil){
             userDefault.setObject("This_is_my_default_message", forKey: "message")
         }

         //如果想单独看某个key的设置，例如:
         let dic = userDefault.dictionaryRepresentation()
         let object_one:AnyObject? = (dic as NSDictionary).objectForKey("AppleKeyboards")
         //        //或者
         //        var object_one:AnyObject?  = dic["AppleKeyboards"]

         if let oValue: AnyObject! = object_one {
             print(oValue)
         }

         //Int类型
         //设置
         userDefault.setInteger(, forKey: "Int")
         //读取
         let intValue = userDefault.integerForKey("Int")
         print(intValue)

         //Float类型
         //设置
         userDefault.setFloat(3.2, forKey: "Float")
         //读取
         let floatValue = userDefault.floatForKey("Float")
         print(floatValue)

         //Double类
         //设置
         userDefault.setDouble(5.6890, forKey: "Double")
         //读取
         let doubleValue = userDefault.doubleForKey("Double")
         print(doubleValue)

         //Bool类型
         //设置
         userDefault.setBool(true, forKey: "Bool")
         //读取
         let boolValue = userDefault.boolForKey("Bool")
         print(boolValue)

         //NSURL类型
         //设置
         userDefault.setURL(NSURL(string: "http://www.iphonetrain.com")!, forKey: "NSURL")
         //读取
         let urlValue = userDefault.URLForKey("NSURL")
         print(urlValue)

 //保存NSDate数据
         //将对象转换成NSData流
         let imageData:NSData = NSKeyedArchiver.archivedDataWithRootObject(UIImage(named: "SwiftClassWeiXin.png")!)

         //存储NSData对象
         userDefault.setObject(imageData, forKey: "imageData")

         //读取数据
         //获取NSData
         let objData:AnyObject? = userDefault.objectForKey("imageData")

         //还原对象-初始一个UIImage对象
         let myImage:AnyObject? = NSKeyedUnarchiver.unarchiveObjectWithData(objData as! NSData)

         print(myImage)

 //自定义的类实现存取需要通过NSData做载体

         //创建AppsModel的实例
         let model = AppsModel(imageName: "appIcon2.png", app_Name: "租房点评", app_Description: "租房被骗？现在开始，你来改变这一切！《租房点评》为你而备，租房无忧！")

         //实例对象转换成NSData
         let modelData:NSData = NSKeyedArchiver.archivedDataWithRootObject(model)

         //存储NSData对象
         userDefault.setObject(modelData, forKey: "myAppModel")

 //保存NSString,
         userDefault.setValue("1_NSString", forKey: "NSString")
         userDefault.setObject("1_NSString1", forKey: "NSString1")

         //保存NSNumber,
         let number:NSNumber = NSNumber(int: )
         userDefault.setValue(number, forKey: "number")
         userDefault.setObject(number, forKey: "number1")

         //保存NSArray
         let array1:NSArray = NSArray(array:["",""])
         userDefault.setValue(array1, forKey: "array")
         userDefault.setObject(array1, forKey: "array1")

         //保存NSDictionary
         let dictionary:NSDictionary = NSDictionary(dictionary: ["":""])
         userDefault.setValue(dictionary, forKey: "dictionary")
         userDefault.setObject(dictionary, forKey: "dictionary1")

 var value:AnyObject? = userDefault.valueForKey("dictionary")
         print(value)

         value = userDefault.objectForKey("dictionary1")
         print(value)

         //-------- 删除所有的值
         let ar:NSDictionary = userDefault.dictionaryRepresentation()

         for key in ar.allKeys {

             userDefault.removeObjectForKey(key as! String)

             userDefault.synchronize()//内存中数据同步更新数据库
         }

2、文件操作

应用开发中所有的非代码文件都存储在沙盒中。

 //1、获取程序的Home目录
         let homeDirectory = NSHomeDirectory()
         print(homeDirectory)

         //2、获取Documents目录
         let documentPaths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)

         let documentPath = documentPaths[]
         print(documentPath)

         //或通过home目录自己追加文件夹
         let documentPath2 = homeDirectory + "/Documents"
         print(documentPath2)

         //3、获取Library目录
         let libraryPaths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.LibraryDirectory, NSSearchPathDomainMask.UserDomainMask, true)
         let libraryPath = libraryPaths[]
         print(libraryPath)

         //或通过home目录自己追加文件夹
         let libraryPath2 = homeDirectory + "/Library"
         print(libraryPath2)

         //4、获取Cache目录
         let cachesPaths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.CachesDirectory, NSSearchPathDomainMask.UserDomainMask, true)
         let cachesPath = cachesPaths[]
         print(cachesPath)

         //或通过home目录自己追加文件夹
         let cachesPath2 = homeDirectory + "/Library/Caches"
         print(cachesPath2)

         //5、获取Tmp目录
         let tmpDir = NSTemporaryDirectory()
         print(tmpDir)

         //或通过home目录自己追加文件夹
         let tmpDir2 = homeDirectory + "/tmp"
         print(tmpDir2)

对文件操作需要先创建一个文件管理器

// 创建文件管理器
        let fileManager :NSFileManager = NSFileManager.defaultManager()

 //创建目录
         //定义几个自己的目录
         let myDirectory1:String = NSHomeDirectory() + "/Documents/myFolder/Images"
         let myDirectory2:String = NSHomeDirectory() + "/Documents/myFolder/Films"
         let myDirectory3:String = NSHomeDirectory() + "/Documents/myFolder/Musics"
         let myDirectory4:String = NSHomeDirectory() + "/Documents/myFolder/Files"

         //创建目录
         //withIntermediateDirectories 设置成true，代表中间所有的路径目录如果不存在，都会创建
         //如果设置成false，因为myFolder目录不存在，所以无法创建1234目录

         //创建myDirectory1目录
         do
         {
             try fileManager.createDirectoryAtPath(myDirectory1, withIntermediateDirectories: true, attributes: nil)
         }
         catch let error as NSError {
             print(error)//如果创建失败，error 会返回错误信息
         }

         //创建myDirectory2目录
         do
         {
             try fileManager.createDirectoryAtPath(myDirectory2, withIntermediateDirectories: true, attributes: nil)
         }
         catch let error as NSError {
             print(error)//如果创建失败，error 会返回错误信息
         }

         //创建myDirectory3目录
         do
         {
             try fileManager.createDirectoryAtPath(myDirectory3, withIntermediateDirectories: true, attributes: nil)
         }
         catch let error as NSError {
             print(error)//如果创建失败，error 会返回错误信息
         }

         //创建myDirectory4目录
         do
         {
             try fileManager.createDirectoryAtPath(myDirectory4, withIntermediateDirectories: true, attributes: nil)
         }
         catch let error as NSError {
             print(error)//如果创建失败，error 会返回错误信息
         }

Swift 的错误处理机制要求你必须使用 do-catch 语句来捕获所有的错误并处理他们。

//创建文件
        let filePath = myDirectory1 + "/appInfo.txt"
        let info = "经常听到：被中介骗了，押金不退，晚一天交房租，被讹了。租房普遍现象：网上报价不真实？经常被忽悠！（看房时报价都比网上高！）证件不齐全，被骗过!（其实根本不是房东啦!）看房前态度都很热情！ 签约之后态度骤变!入住后家电维修只能靠自己！ 房屋到期，押金各种被勒索！现在开始，你来改变这一切！《租房点评》为你而备，租房无忧！再也不用担心被欺骗，想要知道给你介绍房子的人好不好，《租房点评》告诉你！"

通过writeToFile方法，将一些对象写入到文件中

do
        {
            try info.writeToFile(filePath, atomically: true, encoding: NSUTF8StringEncoding)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

//保存图片
        let image = UIImage(named: "SwiftClassWeiXin@3x.png")
        let data:NSData = UIImageJPEGRepresentation(image!, 1.0)!
        let data1:NSData = UIImagePNGRepresentation(image!)!
        data.writeToFile(myDirectory1 + "/SwiftClassIcon.jpg", atomically: true)
        data1.writeToFile(myDirectory1 + "/SwiftClassIcon.png", atomically: true)

        //保存NSArray
        let array = NSArray(objects: "","","")
        array.writeToFile(myDirectory4 + "/array.plist", atomically: true)

        //保存NSDic
        let dictionary = NSDictionary(objects: ["","",""], forKeys: ["","",""])
        dictionary.writeToFile(myDirectory4 + "/dictionary.plist", atomically: true)

//判断目录或文件是否存在
        let exist = fileManager.fileExistsAtPath(filePath)
        print(exist)

        //移动
        let filePath2 = myDirectory4 + "/appInfo.txt"
        do
        {
            try fileManager.moveItemAtPath(filePath, toPath: filePath2)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

        //重命名
        //通过移动该文件对文件重命名
        let filePath3 = myDirectory4 + "/appInfo2.txt"
        do
        {
            try fileManager.moveItemAtPath(filePath2, toPath: filePath3)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

        //拷贝
        let filePath4 = myDirectory4 + "/appInfoCopy.txt"
        do
        {
            try fileManager.copyItemAtPath(filePath3, toPath: filePath4)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

//获取目录列里所有文件名
        //先拷贝一些文件到myDirectory4目录下
        let filePath00 = myDirectory4 + "/appInfoCopy00.txt"
        let filePath11 = myDirectory4 + "/appInfoCopy11.txt"
        let filePath22 = myDirectory4 + "/appInfoCopy22.txt"
        do
        {
            try fileManager.copyItemAtPath(filePath3, toPath: filePath00)
            try fileManager.copyItemAtPath(filePath3, toPath: filePath11)
            try fileManager.copyItemAtPath(filePath3, toPath: filePath22)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

//获取所有文件
        let fileArray = fileManager.subpathsAtPath(myDirectory4)
        print(fileArray)
        //        Optional([appInfo.txt, appInfo2.txt, appInfoCopy.txt, appInfoCopy00.txt, appInfoCopy11.txt, appInfoCopy22.txt])

        //iPhone中获取文件各项属性方法
        //获取文件属性
        do
        {
            var fileAttributes : [NSObject:AnyObject]? = try NSFileManager.defaultManager().attributesOfItemAtPath(filePath22)

            //获取文件的创建日期
            let modificationDate:AnyObject? = fileAttributes![NSFileModificationDate]
            print(modificationDate)

            //获取文件的字节大小
            let fileSize:AnyObject? = fileAttributes![NSFileSize]
            print(fileSize)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

//删除文件
        do
        {
            try fileManager.removeItemAtPath(filePath4)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }

        //删除目录下所有文件
        //方法1： 获取所有文件，然后遍历删除
        let fileArray2 : [AnyObject]? = fileManager.subpathsAtPath(myDirectory4)
        for fn in fileArray2!
        {
            do
            {
                try fileManager.removeItemAtPath(myDirectory4 + "/\(fn)")
            }
            catch let error as NSError {
                print(error)//如果创建失败，error 会返回错误信息
            }
        }

        //方法2：删除目录后重新创建该目录
        do
        {
            try fileManager.removeItemAtPath(myDirectory4)
            try fileManager.createDirectoryAtPath(myDirectory4, withIntermediateDirectories: true, attributes: nil)
        }
        catch let error as NSError {
            print(error)//如果创建失败，error 会返回错误信息
        }
    }