Parameter overloading

Unlike Objective-C, Swift supports parameter overloading, which allows for functions to have the same name and only be differentiated by the parameters that they take.

Let's learn more about parameter overloading by entering the following code into a playground:

func combine(_ givenName: String, _ familyName: String) -> String { 
    return "\(givenName) \(familyName)" 
} 
 
func combine(_ integer1: Int, _ integer2: Int) -> Int { 
    return integer1+integer2 
} 
 
let combinedString = combine("Finnley", "Moon") 
let combinedInt = combine(5, 10) 
print(combinedString) // Finnley Moon 
print(combinedInt) // 15 

Both the preceding functions have the name combine, but one takes two Strings as parameters and the other takes two Ints. Therefore, when we come to call the function, the compiler knows which implementation we intended by the values we pass as parameters.

We've introduced something new in the preceding function declarations--anonymous parameter labels, _ givenName: String.

When we declare the parameters, we use an underscore _ for the parameter label; this indicates that we don't want a parameter name shown when calling the function. This should only be used if the purpose of the parameters is clear without the labels, as is the case in the preceding example--combine("Finnley", "Moon").