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 need to swap two integer types, two Double types, and two String types. 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 these three functions, we can swap the original values of two Integer types, two Double types, and two String types. Now, let's say, as we develop our application further, we find out that we also need to swap the values of two unsigned Integer types, two...