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iOS Swift Closures Closures in iOS Onwards

Paul Je
Paul Je
4,435 Points
Posted by Paul Je
Paul Je
4,435 Points

Question about Closures

I'm pretty confused about Closures as a whole. So is a correct simplification that, if you refer to a constant using a function, which is to return a value regardless of when, you can call it back from another constant later on only when it's ready by possibly integrating an optional? Maybe a potential use of this it that the app or program should only run in procedure A only if the callback returns a non-nil value, but otherwise run in procedure B? Hope that made sense.. any help would be appreciated,

1 Answer

Harish Yerra
Harish Yerra
10,031 Points
Harish Yerra
Harish Yerra
10,031 Points

Well, what a closure is designed to do is provide data that isn't available instantly. So let's take a possible scenario ->

I have an app and I need it to connect to the internet to provide me with some data that my app can use. The data won't be available instantly.

In your question you asked if you can call back later by integrating an optional but that wouldn't be the best because you wouldn't know when your closure is finished executing. The best way to do this would be with a completion handler. A completion handler waits for the closure to finish executing and does something with that data once it's done (possibly calling another function, updating UI, etc).

So basically a closure is just a way of getting data that is fetched asynchronously. You query data in the background, and then once that data is called your completion handler is triggered and you can respond appropriately with the new data.