Use of Swift basic data types

////Viewcontroller.swift//Basic data Types////Created by Ye Shi on 16/9/8.//copyright©2016 year Ye Shi. All rights reserved.//Import UIKitclassViewcontroller:uiviewcontroller {Overridefunc viewdidload () {super.viewdidload ()// Let//Constants//var//variables//                //the Let value cannot be changed using let must initialize                /*character, String*/        //charactervar charvaluel:character ="Q"        //stringvar charvalue2:string ="123"                //initialize an empty stringvar charValue3=""var charValue4=String ()//determines whether a string is empty        ifcharvalue2.isempty {print ("string is empty")        }        //or                ifCharValue3 = =""{print ("string is empty")        }                //Assigning a value to a stringLet emptystring ="ABC"Let emptyString2= String ("ABC")                //to traverse a character in a string         forCinchemptystring2.characters {print (c)}/** Yuan zu*/                //the values within the progenitor can be of any type, and the ancestors do not have to be of the same type//define a meta-ancestorLet product= ( -,"iphone 6s",6088) print (product)//get every element in the meta-ancestorvar (_year, _name, _price) =Product Print ("Year = \ (_year)","_name=\ (_name)","price=\ (_price)")                //enter only one valueLet (_, Name1, _)=Product Print ("name\ (name1)")                //You can use dot syntaxLet product2= (Year: -, Name:"iphone 6s", Price:6088) print (product2.year) print (product2.name) print (Product2.price)/*Optional Type*/var stringvalue:string//Print (stringvalue) compilation does not pass, no initializationvar stringvalue2:string?if(StringValue2! =Nil) {Print (StringValue2!)        }        //If the string is "" Use! will print crash use? output to nil//that means there must be a value.var numstr:string ="123"var value1:int? =Int (numstr) print (value1)/** Number worth readability*/Let readabilty1=100000000; Let Readabilty2=1_000_000_000_1/** Type alias*/                //A type alias is one that takes a more meaningful alias (the new type) to a type, using the Typealias keyword//The format is as followsTypealias Newint=Int32 var new_value:newint=123print (New_value)/** Conversions between basic data types*/                //convert int type to other typevar j:int=3Double (j) Float (j)//String type go Int Float Double typevar s:string="2.156ASD2"                //when the first character is not a number, a Double is 0//when the first digit of a character is a number, it can be converted directly to a number, and a number that precedes a non-character is stopped.Int (s) print ("-------", s) var s2= S asnsstring Print (s2.integervalue) print (s2.floatvalue) print (S2.doublevalue) //Double Float Int turn Stringvar d:double=1.68        "\ (d)"var f:float=3.134        "\ (f)"var i:int=1        "\ (i)"                //You cannot use String (INT) directly to set the numeric value of a character in the form of "\ (value)"//int can be used directly with Double (int) Float (int)                /** operator*/                /** ++i is i= i+1 and-i is i = i-1*/        //Unary OperatorsLet three =-3Let minusthree= -three let Plusthree= -minusthree Print (Minusthree, plusthree)//As type conversion//is type check                                                                                                            }    Overridefunc didreceivememorywarning () {super.didreceivememorywarning ()//Dispose of any resources the can be recreated.    }}

Use of Swift basic data types