Functions

So far we have called some Objective-C functions but we have not defined any yet. Let's see what the Objective-C versions are of the functions we defined in Chapter 2, Building Blocks – Variables, Collections, and Flow Control.

Our most basic function definition didn't take any arguments and didn't return anything. The Objective-C version looks similar to the following code:

func sayHello() {
    print("Hello World!");
}
sayHello()
void sayHello() {
    NSLog(@"Hello World!");
}
sayHello();

Objective-C functions always starts with the type that the function returns instead of the keyword func. In this case, we aren't actually returning anything, so we use the keyword void to indicate that.

Functions that take arguments and return values have more of a disparity between the two languages:

func addInviteeToListIfSpotAvailable
    (
    invitees: [String],
    newInvitee: String
    )
    -> [String]
{
    if invitees.count >= 20 {
        return invitees
    }
    return invitees...