【Swift 60秒】51 - Closures as parameters

0x00 Lesson

Because closures can be used just like strings and integers, you can pass them into functions. The syntax for this can hurt your brain at first, so we’re going to take it slow.

First, here’s our basic driving() closure again

let driving = {
	print("I'm driving in my car")
}
1
2
3

If we wanted to pass that closure into a function so it can be run inside that function, we would specify the parameter type as () -> Void. That means “accepts no parameters, and returns Void” - Swift’s way of saying “nothing”.

So, we can write a travel() function that accepts different kinds of traveling actions, and prints a message before and after:

func travel(action: () -> Void) {
	print("I'm getting ready to go.")
	action()
	print("I arrived!")
}
1
2
3
4
5

We can now call that using our driving closure, like this:

travel(action: driving)
1

---

0x01 我的小作品

欢迎体验我的作品之一：小笔记-XNote
笔记一步到位！
App Store 搜索即可~

---