Get integer value from string in swift

Question

Swift 2.0 you can initialize Integer using constructor

var stringNumber = "1234"
var numberFromString = Int(stringNumber)

I'd use:

var stringNumber = "1234"
var numberFromString = stringNumber.toInt()
println(numberFromString)

Note toInt():

If the string represents an integer that fits into an Int, returns the corresponding integer.

In Swift 3.0

Type 1: Convert NSString to String

    let stringNumb:NSString = "1357"
    let someNumb = Int(stringNumb as String) // 1357 as integer

Type 2: If the String has Integer only

    let stringNumb = "1357"
    let someNumb = Int(stringNumb) // 1357 as integer

Type 3: If the String has Float value

    let stringNumb = "13.57"
    if let stringToFloat = Float(stringNumb){
        let someNumb = Int(stringToFloat)// 13 as Integer
    }else{
       //do something if the stringNumb not have digit only. (i.e.,) let stringNumb = "13er4"
    }

The method you want is toInt() -- you have to be a little careful, since the toInt() returns an optional Int.

let stringNumber = "1234"
let numberFromString = stringNumber.toInt()
// numberFromString is of type Int? with value 1234

let notANumber = "Uh oh"
let wontBeANumber = notANumber.toInt()
// wontBeANumber is of type Int? with value nil

If you are able to use a NSString only.

It's pretty similar to objective-c. All the data type are there but require the as NSString addition

    var x = "400.0" as NSString 

    x.floatValue //string to float
    x.doubleValue // to double
    x.boolValue // to bool
    x.integerValue // to integer
    x.intValue // to int

Also we have an toInt() function added See Apple Inc. “The Swift Programming Language.” iBooks. https://itun.es/us/jEUH0.l page 49

x.toInt()