I have an iPhone app which pretty much is a mobile app for a website. Pretty much everything it does is call API methods from our server. The app retrieves the user’s information, and keeps updating the server using the API.
My colleague and I had a discussion whether to introduce GCD to the downloading aspect on the app. My colleague argues that since the UI needs to wait for the download to complete before it can display the pictures, text or whatever, there is absolutely no need for GCD. My argument is that we should keep the main thread busy with UI rendering (even if there is no data), and introduce GCD to the app to create other threads for download.
Which argument is right here? In my case, if the UI renders with no data, will there be some sort of lag? Which will yield a cleaner, sleeker and faster app?
A more appropriate question would perhaps be if you should download asynchronously or on the main thread for your app, since there are several different methods to download asynchronously on iOS (e.g. using NSThread, NSOperation or indeed GCD). An easy approach to achieve your goals could be to use the AFNetworking library. It makes multithreaded networking / internet code very easy to implement and understand.
Personally I’m very fond of GCD and recommend you learn it someday soon, though in itself it is not as suitable for asynchronous downloading compared to a library like AFNetworking (that uses GCD under the hood, I believe).