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)!")
}

The parameter is called ​​to name​​​, which means ​​externally​​​ it’s called ​​to​​​, but ​​internally​​​ it’s called ​​name​​. This gives variables a sensible name inside the function, but means calling the function reads naturally:

sayHello(to: "Taylor")

0x01 我的小作品

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