Mastering Swift 3

Generic functions

Let's begin by examining the problem that generics try to solve and then we will see how generics solve this problem. Let's say that we wanted to create functions that swapped the values of two variables (as described in the first part of this chapter); however, for our application, we have a need to swap two Int types, two Double types, and two String types. Without generics, this would require us to write three separate functions. The following code shows what these functions could look like:

func swapInts (a: inout Int,b: inout Int) { 
    let tmp = a 
    a = b 
    b = tmp 
} 
 
func swapDoubles(a: inout Double,b: inout Double) { 
    let tmp = a 
    a = b 
    b = tmp 
} 
 
func swapStrings(a: inout String, b: inout String) { 
    let tmp = a 
    a = b 
    b = tmp 
} 

With ...