Loop n times in Swift

There are many ways to loop in Swift. In this post, I will show you how I do when I want to loop for a specific number of times.

How to loop n times with for-in loop

To run a code exactly n times in Swift, I think for-in loops with closed range operator (...) convey the clearest message.

Here is an example of running a code for five times.

for i in 1...5 {
    print(i)
}
// 1
// 2
// 3
// 4
// 5

You can achieve the same thing with half-open range (0..<5) or a different range 0...4, but I prefer to use 1...5 instead of 0...4 or 0..<5 because it is easier to understand to me since it matched the way we count in real-world.

• 0...4 matched how we normally count in programming, but it lack the actual number of times that we want to execute, 5.
• 0..<5 contain the number 5, but I think it is more confusing than 0...4.

You can easily support sarunw.com by checking out this sponsor.

Tiny OCR: Extract text from image directly from your mac.

Try it for Free

How to loop n times with forEach

You can also use forEach to achieve the same effect.

(1...5).forEach { i in
    print(i)
}
// 1
// 2
// 3
// 4
// 5

You can easily support sarunw.com by checking out this sponsor.

Tiny OCR: Extract text from image directly from your mac.

Try it for Free

Make it more Rubyist

In Ruby^[1], you can loop for a specific number of times using an Integer's method, times.

Here is an example of how we loop five times in Ruby.

5.times do |i|
  puts i
end
// 0
// 1
// 2
// 3
// 4

Let's try to do this in Swift just for fun.

extension Int {
    func times(_ callback: (Int) -> ()) {
        // 1
        if self > 0 {
            // 2
            for i in 0..<self {
                callback(i)
            }
        }
    }
}

1 First, we check if the number is more than zero.
2 Then we loop and return the value starting from zero (to make it match the implementation of the Ruby).

Then we can use it like this.

5.times { i in
    print(i)
}
// 0
// 1
// 2
// 3
// 4

Normally, I won't introduce trivial extensions like this to the codebase because I think it causes more harm than good.

But this is totally up to your judgment. I just want to show how easy it is for you to extend Swift's capability.