Functions

Declaration

func DoSomeWork(param1: String, param2: Int)
{
    println("I saw \(param1) \(param2) times.")
}
// How to call
DoSomeWork("Sally", 3)

// Default Parameters
func DoSomeWork(param1: String, param2: Int = 2)
{
    println("I saw \(param1) \(param2) times.")
}
// How to call
DoSomeWork("Sally")
// or
DoSomeWork("Sally", param2: 5)

// Note: With default parameters you HAVE to use the 
// parameter name.

//Multiple Default Parameters
func DoSomeWork(name: String, howMany: Int=1, didSee: Bool=false)
{
    if didSee {
        println("I saw \(name) \(howMany) times.")
    }
    else {
        println("I did not see \(name) at all.")
    }
}

// How to call
DoSomeWork("Sally")
// or
DoSomeWork("Sally", didSee: true)
// or
DoSomeWork("Mark", didSee: true, howMany: 3)

// Notice how I can reorder the default parameters.

External Parameter Names

// Add extra argument info (called "argument labels")
// to help developers better understand what is happening
func DoSomeWork(forThisPerson param1: String, thisManyTimes param2: Int)
{
    println("I worked for \(param1) \(param2) times.")
}
How to call
DoSomeWork(forThisPerson: "Sally", thisManyTimes: 3)

// Note: If you do not include the argument labels 
// (external parameter names) you will get this issue:
// "Missing argument label 'thisManyTimes:' in call"

// One Parameter Name
// If you just want one parameter name but you still want 
// to force developers to type it out when calling then 
// you can use the pound (#) symbol in front of the parameter name.
func DoSomeWork(#forThisPerson: String, #thisManyTimes: Int)
{
    println("I worked for \(forThisPerson) \(thisManyTimes) times.")
}
How to call

DoSomeWork(forThisPerson: "Sally", thisManyTimes: 3)
Return a variable
func ReturnVariable() -> Bool
{
    return true
}