example usage of optional type in swift

example usage of optional type.swift

var exampleDictionary = ["foo":1,"bar":2]

// an optional type means its value can either be some certain type or nothing at all( nil)
var optionalTypeVariable: Int? = exampleDictionary["someUncertainValue"]

// calling optionalTypeVariable will either return an integer or a nil, so you should normally check it’s value before actually using it
if optionalTypeVariable == nil {
    println("The value of optionalTypeVariable is nil")
} else {
    // calling optionalTypeVariable! will always return an integer, if optionalTypeVariable is in fact nil, then an assertion will be triggered.
    let IntegerConstant: Int = optionalTypeVariable!
    println("The value of optionalTypeVariable is /(IntegerConstant)")
}

// short version
if let IntegerConstant = optionalTypeVariable {
    println("The value of optionalTypeVariable is /(IntegerConstant)")
} else {
    println("The value of optionalTypeVariable is nil")
}