CareerCup

This question was asked to one of my friends, so I am not sure about the exact question details. I have the following questions:

1. How is a function passed to another function?
2. Can't we just use the sleep method?

I think this to be a system design question.

Essentially the same question:
careercup.com/question?id=4509450021896192
Since interviewers gives milliseconds and might have a devices background, depending on allowed jitter, you might need to use RTC events, if that's easily available on your OS. You can craft this into the entioned algo.

Yes, it makes sense. Thank you as always, ChrisK! :)

I guess that's why it's a decent question to ask.

Some fundamentals behind this would be knowing what a function inside of a function is? Apple refers to this as a closure expression, and can be short handed as a trailing closure.

Good examples of these are URLSessions and UIView.animate methods. You're essentially passing a closure (which is a function) and saying, "I'm not sure what the value is, but here's a recipe on how to use the value when you get it."

Sleeping would work but you'll most likely doing that on main which isn't the best idea. A good example of using both of these together would be to actually just do:

func execute(after time: Int, f: @escaping () -> Void) {
	DispatchQueue.main.async(deadline: .now() + .milliseconds(time), execute: f)
}

// Usage:
execute(after: 250) { [weak self] in
	self?.title = "Example"
}

The weak self is known as a capture list which protects from creating reference cycles and executing when the instance has been deinitialized.

@lkjhgfdsa -

Simply call the another method by itself thats only calling and passing function to another function