Swift Functions

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Swift Functions

Functions (with inputs)

func MyFunction(m: String, n: Int){
    print(m)
}
 
MyFunction(m: "Hello")
 
>> Hello

Function output

func MyFunction() -> Int{
    return 123
}
 
// The type after the -> indicates the type of data that function will output

Function labels

Three ways to label parameters: no label, word label, or underscore label.

// No Labels
func DoAdd(a:Int, b:Int) -> Int{
    var sum = 5 + 7
    return sum
}
 
DoAdd(a:5, b:7)
 
// With word labels
func DoAdd(firstNum a:Int, secNum b:Int) -> Int{
    var sum = 5 + 7
    return sum
}
 
DoAdd(firstNum:5, secNum:7)
 
// With underscore labels
func DoAdd(_ a:Int,_ b:Int) -> Int{
    var sum = 5 + 7
    return sum
}
 
DoAdd(5,7)

Function signatures

The function signature is the combination of function name and parameter labels (not just the name). So these two are different signatures even though both are named DoAdd:

// ONE
func DoAdd(a:Int, b:Int) -> Int{
    var sum = 5 + 7
    return sum
}
DoAdd(a:5, b:7)
 
// TWO
func DoAdd(_ a:5, _ b:7) -> Int{
    var sum = 5 + 7
    return sum
}
DoAdd(5,7)

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