swift 簡介和常量與變數 --- swift 入門

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一、思維導圖

二、

代碼

//建立UIView 和按鈕     let views = UIView(frame: CGRect(x:20, y: 20, width: 100, height: 100))//FIXME:改變viewsframe        views.backgroundColor = UIColor.yellow        view.addSubview(views)                //MARK: 建立一個按鈕        let Button2 = UIButton(type: .contactAdd)        Button2.backgroundColor = UIColor.red  //FIXME:sfsl        Button2.frame = views.bounds        views.addSubview(Button2)                //        Button2 .addTarget(self, action: #selector(button2Click), for:)        Button2.addTarget(self, action: #selector(button2Click), for: .touchUpInside)    }    //MARK:-- methods response    func button2Click()  {        print("按鈕單擊")    }

//常量和變數
1   let a = 102         let b:Double = 105.33         // Binary operator ‘+‘ cannot be applied to operands of type ‘Int‘ and ‘Double‘4         print(a+Int(b))5        6         7         var name:String = "Hello Word" //不管是變數還是常量必須初始化，且常量的值不能改變8         name = "我是 Hello Word"9          print(name)

 //分支和三運算 //1 if f        let a = 10                if a > 5 {            print("a>5")        }else{            print("a<5")        }        //2 三目        //        a > 5 ? print("a大") : print("a小")        //或寫成        a > 5 ? print("a大大大") :()

 

swift 簡介和常量與變數 --- swift 入門