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iOS

Posted by Mitch Little
Mitch Little
11,870 Points

Networking Requests in iOS

Good afternoon,

I understand the overall process of making a Network Request to an API, how to Parse the returned JSON, populate Data Model Objects, and display the data through the view controller.

I can quite easily read through Networking Code examples and understand what is happening.

What I am struggling with is realising what the Completion Handler actually does. I do understand that it is an escaping closure that is called when the request has finished due to running on a back ground thread.

However when actually looking through code, the 'completion' parameter is used in a function, but doesn't actually seem to do anything at all. It appears to be assigned Data, and Errors returned from the .dataTask / .jsonObject methods or from Error Enums.

I do understand how the closure uses the Response , Data Or Errors. Just don't understand why they are assigned to a 'completion' parameter.

I just can't see what the Completion Handler actually implements or how it is used.

Any would would be greatly appreciated,

Thank you,

Mitch