Best architectural approaches for building iOS networking applications (REST clients)

Question

I\'m an iOS developer with some experience and this question is really interesting to me. I saw a lot of different resources and materials on this topic, but nevertheless I\

Answer 1

To my mind all software architecture is driven by need. If this is for learning or personal purposes, then decide the primary goal and have that drive the architecture. If this is a work for hire, then the business need is paramount. The trick is to not let shiny things distract you from the real needs. I find this hard to do. There are always new shiny things appearing in this business and lots of them are not useful, but you can't always tell that up front. Focus on the need and be willing to abandon bad choices if you can.

For example, I recently did a quick prototype of a photo sharing app for a local business. Since the business need was to do something quick and dirty, the architecture ended up being some iOS code to pop up a camera and some network code attached to a Send Button that uploaded the image to a S3 store and wrote to a SimpleDB domain. The code was trivial and the cost minimal and the client has an scalable photo collection accessible over the web with REST calls. Cheap and dumb, the app had lots of flaws and would lock the UI on occasion, but it would be a waste to do more for a prototype and it allows them to deploy to their staff and generate thousands of test images easily without performance or scalability concerns. Crappy architecture, but it fit the need and cost perfectly.

Another project involved implementing a local secure database which synchronizes with the company system in the background when the network is available. I created a background synchronizer that used RestKit as it seemed to have everything I needed. But I had to write so much custom code for RestKit to deal with idiosyncratic JSON that I could have done it all quicker by writing my own JSON to CoreData transformations. However, the customer wanted to bring this app in house and I felt that RestKit would be similar to the frameworks that they used on other platforms. I waiting to see if that was a good decision.

Again, the issue to me is to focus on the need and let that determine the architecture. I try like hell to avoid using third party packages as they bring costs that only appears after the app has been in the field for a while. I try to avoid making class hierarchies as they rarely pay off. If I can write something in a reasonable period of time instead of adopting a package that doesn't fit perfectly, then I do it. My code is well structured for debugging and appropriately commented, but third party packages rarely are. With that said, I find AF Networking too useful to ignore and well structured, well commented, and maintained and I use it a lot! RestKit covers a lot of common cases, but I feel like I've been in a fight when I use it, and most of the data sources I encounter are full of quirks and issues that are best handled with custom code. In my last few apps I just use the built in JSON converters and write a few utility methods.

One pattern I always use is to get the network calls off the main thread. The last 4-5 apps I've done set up a background timer task using dispatch_source_create that wakes up every so often and does network tasks as needed. You need to do some thread safety work and make sure that UI modifying code gets sent to the main thread. It also helps to do your onboarding/initialization in such a way that the user doesn't feel burdened or delayed. So far this has been working rather well. I suggest looking into these things.

Finally, I think that as we work more and as the OS evolves, we tend to develop better solutions. It has taken me years to get over my belief that I have to follow patterns and designs that other people claim are mandatory. If I am working in a context where that is part of the local religion, ahem, I mean the departmental best engineering practices, then I follow the customs to the letter, that's what they are paying me for. But I rarely find that following older designs and patterns is the optimal solution. I always try to look at the solution through the prism of the business needs and build the architecture to match it and keep things as simple as they can be. When I feel like there isn't enough there, but everything works correctly, then I'm on the right track.