Introduction to Swift and constants and variables---Introduction to Swift

First, mind map

Two

Code

//Create UIView and buttonsLet's views = UIView (Frame:cgrect (x:20, y:20, width:100, height:100))//fixme: Change ViewsframeViews.backgroundcolor =uicolor.yellow View.addsubview (views)//MARK: Create a buttonLet Button2 =UIButton (type:. Contactadd) Button2.backgroundcolor= uicolor.red//FIXME:SFSLButton2.frame =views.bounds Views.addsubview (Button2)//Button2. AddTarget (Self, Action: #selector (Button2click), for:)Button2.addtarget (Self, Action: #selector (Button2click), for:. Touchupinside)} //mark:--Methods Responsefunc Button2click () {print ("Button click")    }

//Constants and variables
1Let A =Ten2Let b:double =105.33         //Binary operator ' + ' cannot is applied to operands of type ' Int ' and ' Double '4Print (A +Int (b))5        6         7var name:string ="Hello Word" //either the variable or the constant must be initialized, and the value of the constant cannot be changed8Name ="I am Hello Word"9Print (name)

Branching and//1 if f let        a = ten                if a > 5 {            print ("a>5")        }else{            print ("A<5")        }        // 23 Mesh        /        a > 5 print ("A large"): Print ("a small")        //or write as        a > 5? print ("A large"):()

Introduction to Swift and constants and variables---Introduction to Swift