【Swift 60秒】40 - Parameter labels

0x00 Lesson

We wrote our ​

​square()​

​ function like this:

func square(number: Int) -> Int {
  return number * number
}      

That names its parameter ​

​number​

​​, so we can use ​

​number​

​ inside the function to refer to it, but we must also use the name when running the function, like this:

let result = square(number: 8)      

Swift lets us provide ​

​two​

​​ names for each parameter: ​

​one​

​​ to be used ​

​externally​

​​ when calling the function, and ​

​one​

​​ to be used ​

​internally​

​​ inside the function. This is as simple as writing two names, separated by a ​

​space​

​.

To demonstrate this, here’s a function that uses two names for its string parameter:

func sayHello(to name: String) {
  print("Hello, \ (name)!")
}      

sayHello(to: "Taylor")      

0x01 我的小作品