7/10/2016 - 4:55 AM

iphone app

iphone app


declare a variable and constant

  • variable

    var i = 10

  • constant

    let constant = "constant"

String interpolation

If the initial value dosent provide enough info. then we can write a type seperated by colon

let value: Double 10

option click on variable gives the variable information

Values as never implicitly converted as in java let widthLabel = label + String(width) note (String)width even if width is an integer you have to tell compiler to convert it to String

You can use string interpolation to include values in string \(String)

let appleSummary = "I have \(apples) apples."


optionals are values that might be nil so you declare them with ? let i:Int? = 10. i is int type but is optional, it can be nil

let optionalInt: Int? = 9

You can extract the value of optional with a bang !

let anotherInt:Int = optionalInt!


possibleInt = "banana" var myString = (Int)possibleInt

In above case myString is nil


var aList = ["a","b","c","d"]

aList[0] = "z"