[IOSS]Swift数据类型转换

/*
        整型 -> 浮点
        */
        let intLet : Int = 5
        let doubleLet : Double = Double(intLet)
        let floatLet : Float = Float(intLet)
        print(intLet,doubleLet,floatLet)
        
        /*
        字符串 -> 整型
        */
        //swift1.x的语法
        //let intString: String = "256"
        //let transformInt: Int? = intString.toInt()
        //swift2.x的语法
        let intString: String = "123456"
        let transformInt: Int? = Int(intString)
        print(transformInt!)
        print(transformInt) //不加" ！"时打印后后有默认值 Optional(123456)

        /*
        整型 -> 字符串
        */
        let intFive : Int = 5
        let strFive : String = String(intFive)
        print(strFive)
        
        /*
        浮点 -> 字符串
        */
        let double : Double = 20.12
        let stringDouble = NSString(format: "%f",double)
        let stringDouble_ : String = String( double )
        print(stringDouble,stringDouble_)
        /*
        字符串 -> 浮点
        */
        let strDouble : String = "20.12"
        let doubleStr : Double = (strDouble as NSString).doubleValue
        let doubleStr_ : Double = NSString(string: strDouble).doubleValue
        print(doubleStr,doubleStr_)