6.5、UserDefault

视图入口
import UIKit

class ViewController: UIViewController {
  override func viewDidLoad() {
      super.viewDidLoad()
      //NSUserDefaults的使用,NSUserDefaults使用的是单例对象
      //1.获取
      let btn = UIButton(type: .system)
      btn.frame = CGRect(x: 100, y: 200, width: 100, height: 40)
      btn.setTitle("获取", for: UIControlState())
      btn.addTarget(self, action: #selector(clickBtn), for: .touchUpInside)
      self.view.addSubview(btn)
      btn.tag = 101
      
      //2.存储
      let saveBtn = UIButton(type: .system)
      saveBtn.frame = CGRect(x: 100, y: 300, width: 100, height: 40)
      saveBtn.setTitle("存储", for: UIControlState())
      saveBtn.addTarget(self, action: #selector(saveAction), for: .touchUpInside)
      self.view.addSubview(saveBtn)
      
      //3.删除
      let deleteBtn = UIButton(type: .system)
      deleteBtn.frame = CGRect(x: 100, y: 400, width: 100, height: 40)
      deleteBtn.setTitle("删除", for: UIControlState())
      deleteBtn.addTarget(self, action: #selector(deleteAction), for: .touchUpInside)
      self.view.addSubview(deleteBtn)
  }
  //存储
  func saveAction(){
//NSUserDefaults适合存储轻量级的本地客户端数据，比如记住密码功能，要保存一个系统的用户名、密码。使用NSUserDefaults是首选。下次再登陆的时候就可以直接从NSUserDefaults里面读取上次登陆的信息。
//NSUserDefaults支持的数据格式也很多，有：Int，Float，Double，BOOL，甚至AnyObject类型。
      
//1、获取单例对象
      let ud = UserDefaults.standard
//2、对原生数据类型的储存和读取
      ud.set("张三", forKey: "name")
      //存储字典
      var person = [String:Any]()
      person["name"] = "aixi"
      ud.set(person, forKey: "PERSON")
//3，系统对象的存储与读取 UIImage
//        系统对象实现存储，需要通过archivedDataWithRootObject方法转换成NSData为载体，才可以存储。下面以UIImage对象为例：
      let image = UIImage(named: "2")
      let imageData:NSData = NSKeyedArchiver.archivedData(withRootObject: image ?? "3") as NSData
      ud.set(imageData, forKey: "imageData")
//        自定义对象的存储和读取
//        如果想要存储自己定义的类，首先需要对该类实现NSCoding协议来进行归档和反归档（序列号和反序列化）。即该类内添加func encodeWithCoder(_encoder:NSCoder)方法和init(coder decoder:NSCoder)方法，并继承协议，然后将属性进行转换。
      //自定义对象存储
      let model = PersonModel(names: "WeiWei", ages: "18", weights: 100)
      //实例对象转换成NSData
      let modelData = NSKeyedArchiver.archivedData(withRootObject: model)
      //存储NSData对象
      ud.set(modelData, forKey: "modelData")

      //使用扩展存储
      ud.saveCustomObject(customObject: model, key: "extensionDuixiang")
      //同步到文件
      ud.synchronize()
      /*
       NSUserDefaults实现的原理
       系统里面有一个文件来存储NSUserDefaults里面的数据
       在程序启动的时候，系统将这个文件里面的所有数据读到内存里面
       我们修改的数据只是修改了内存里面的数据
       但是这个数据没有同步到文件里面,下一次使用的时候这个数据就没有
       所以在程序结束之前我们都应该将内存里面的数据同步到文件
       */
  }
  //获取
  func clickBtn(){
      let ud = UserDefaults.standard
      let name = ud.object(forKey: "name")
      //获取字符串
      if let tmpName = name {
          print("获取字符串",tmpName)
          let alert = UIAlertController(title: "温馨提示", message: "获取到值", preferredStyle: .alert)
          alert.addAction(UIAlertAction(title: "ok", style: .default, handler: nil))
          self.present(alert, animated: true, completion: {
              print("提示弹出后调用打印函数")
          })
      }
      //获取字典中的值
      let person = ud.object(forKey: "PERSON")
      if var perDict:Dictionary = person as? Dictionary {
          print("获取字典中的值",perDict["name"]!)
      }
      
      //UIImage对象读取
      //获取NSData
      let objData = ud.object(forKey: "imageData")
      if let imageData:NSData = objData  as? NSData {
          //还原对象
          let myImage = NSKeyedUnarchiver.unarchiveObject(with: imageData as Data) as! UIImage
          let btn:UIButton = self.view.viewWithTag(101) as! UIButton
          btn.setBackgroundImage(myImage, for: .normal)
          print("获取NSData",myImage)
      }

      //自定义对象读取
      let modelData = ud.object(forKey: "modelData")
      if let models = modelData {
          let myModel = NSKeyedUnarchiver.unarchiveObject(with: models as! Data) as! PersonModel
          print("自定义对象的值",myModel.name,myModel.age,myModel.weight)
      }
      
      //使用扩展获取
     let extenModel = ud.getCustomObject(forKey: "extensionDuixiang")
      if let dataModels:PersonModel = extenModel as? PersonModel {
          print("扩展的user default==",dataModels.age)
      }
  }
  //删除
  func deleteAction(){
      let ud = UserDefaults.standard
      ud.removeObject(forKey: "name")
      ud.removeObject(forKey: "PERSON")
      ud.removeObject(forKey: "imageData")
      ud.removeObject(forKey: "modelData")
      ud.removeObject(forKey: "extensionDuixiang")

      //同步
      ud.synchronize()
  }
}

UserDefaults扩展
import Foundation
extension UserDefaults {
    //存储
    func saveCustomObject(customObject: NSCoding, key: String) {
        let encodedObject = NSKeyedArchiver.archivedData(withRootObject: customObject)
        self.set(encodedObject, forKey: key)
        self.synchronize()
    }
    //获取
    func getCustomObject(forKey key: String) -> AnyObject? {
        let decodedObject = self.object(forKey: key) as? NSData
        if let decoded = decodedObject {
            let object = NSKeyedUnarchiver.unarchiveObject(with: decoded as Data)
            return object as AnyObject
        }
        return nil
    }
    //移除
    func removeCustomObject(key: String){
        self.removeObject(forKey: key)
        self.synchronize()
    }
}

数据模型
import UIKit

class PersonModel: NSObject,NSCoding {
    var name:String
    var age:String
    var weight:Int
    init(names:String,ages:String,weights:Int) {
        self.name = names
        self.age = ages
        self.weight = weights
        super.init()
    }
//当我们在子类定义了指定初始化器(包括自定义和重写父类指定初始化器)，那么必须显示实现required init?(coder aDecoder: NSCoder)，而其他情况下则会隐式继承，我们可以不用理会。
    //提供一个解码器解码数据，通过解码数据来初始化类变量
//    MARK:- 处理需要解档的字段
    required init(coder aDecoder:NSCoder){
        self.name = aDecoder.decodeObject(forKey: "name") as! String
        self.age = aDecoder.decodeObject(forKey: "age") as! String
        self.weight = Int(aDecoder.decodeInt32(forKey: "weight"))
    }
    //提供一个编码器编码数据
    // MARK:- 处理需要归档的字段
    func encode(with aCoder: NSCoder) {
        aCoder.encode(name,forKey:"name")
        aCoder.encode(age,forKey:"age")
        aCoder.encode(weight,forKey:"weight")
    }
}