使用UserDefaults来进行本地数据存储

UserDefaults 支持的数据格式也很多，有：Int，Float，Double，BOOL，Array，Dictionary，甚至 Any 类型。

        let user = UserDefaults.standard
        
        //Any
        user.set("wc", forKey: "value")
        let value:Any? = user.object(forKey: "value")
        print("value==============\(value)")
        
        //Int
        user.set(1234, forKey: "IntValue")
        let intValue:Int = user.integer(forKey: "IntValue")
        print("intValue==============\(intValue)")
        
        //Float
        user.set(12.33, forKey: "FloatValue")
        let floatValue:Float = user.float(forKey: "FloatValue")
        print("floatValue=============\(floatValue)")
        
        //Double
        user.set(1.234, forKey: "DoubleValue")
        let doubleValue:Double = user.double(forKey: "DoubleValue")
        print("doubleValue==============\(doubleValue)")
        
        //Bool
        user.set(true, forKey: "BoolValue")
        let boolValue:Bool = user.bool(forKey: "BoolValue")
        print("boolValue===============\(boolValue)")
        
        //Url
        let url1:URL = URL(string: "https://www.baidu.com")!
        user.set(url1, forKey: "URLValue")
        let urlValue:URL = user.url(forKey: "URLValue")!
        print("urlValue===============\(urlValue)")
        
        //String
        user.set("123", forKey: "StringValue")
        let stringValue:String = user.string(forKey: "StringValue")!
        print("stringValue============\(stringValue)")
        
        //NSNumber
        var number = NSNumber(value:22)
        user.set(number, forKey: "NSNumber")
        number = user.object(forKey: "NSNumber") as! NSNumber
        print("number=-=========\(number)")
        
        //Array类型
        var array:Array = ["123","456"]
        user.set(array, forKey: "Array")
        array = user.array(forKey: "Array") as! [String]
        
        
        //Dictionary类型
        var dictionary = ["1":"hangge.com"]
        user.set(dictionary, forKey: "Dictionary")
        dictionary = user.dictionary(forKey: "Dictionary") as! [String : String]

//系统对象实现存储，需要通过 archivedData 方法转换成 Data 为载体，才可以存储。
        //UILabel对象存储
        //将对象转换成Data流
        let label = UILabel()
        label.text = "欢迎访问hangge.com"
        let labelData = NSKeyedArchiver.archivedData(withRootObject: label)
        //存储Data对象
        user.set(labelData, forKey: "labelData")
        
        //UILabel对象读取
        //获取Data
        let objData = user.data(forKey: "labelData")
        //还原对象
        let myLabel = NSKeyedUnarchiver.unarchiveObject(with: objData!) as? UILabel
        print(myLabel as Any)

        //如果我们过直接把 image1 存储起来，再取出转换回 UIImage 就变成了 nil。必须先转成 image2 再存储。
        //UIImage对象存储
        //将对象转换成Data流
        let image1 = UIImage(named: "apple.png")!
        let image2 = UIImage(cgImage: image1.cgImage!, scale: image1.scale,
                             orientation: image1.imageOrientation)
        let imageData = NSKeyedArchiver.archivedData(withRootObject: image2)
        //存储Data对象
        user.set(imageData, forKey: "imageData")
        
        //UIImage对象读取
        //获取Data
        let iiiimg = user.data(forKey: "imageData")
        //还原对象
        let myImage = NSKeyedUnarchiver.unarchiveObject(with: iiiimg!) as? UIImage
        print(myImage)

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（序列化和反序列化）。即该类内添加 func encode(with coder: NSCoder) 方法和 init(coder decoder: NSCoder) 方法，将属性进行转换。