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iOS Build a Weather App with Swift Managing Complexity Methods with Closures

Posted by williamho3
williamho3
9,799 Points

I dont understand why we want the downloadJSONFromURL method to return void - dont we want it to return a Dictionary?

Dont we want downloadJSONFromURL to give us a dictionary to use in the same way that we used the plist earlier. I dont quite understand why we would want it to return void. Thanks for the help!!!

1 Answer

Joe Lennon
Joe Lennon
2,074 Points

It's because the downloadJSONFromURL method makes an asynchronous network request. This means the function will complete before the network request returns a response. As a result, rather than returning the JSON data from the function like with a synchronous function, instead it is passed to a callback closure, in this case the completion argument of the method.

One of the earlier videos in this series talks about concurrency - I recommend you rewatch this if you don't understand the concepts of asynchronous code.