Summary

At the start of this chapter, we had a discussion about running tasks concurrently compared to running tasks in parallel. We also discussed the hardware limitations that restrict how many tasks can run in parallel on a given device. Having a good understanding of these concepts is very important to understanding how and when to add concurrency to our projects.

We learned about GCD and operation queues, two different ways of implementing concurrency. While GCD is not limited to system-level applications, before we use it in our application, we should consider whether operation queues would be easier and more appropriate for our needs. In general, we should use the highest level of abstraction that meets our needs. This will usually point us to using operation queues; however, there really is nothing preventing us from using GCD, and it may be more appropriate for our needs.

We should always consider whether it is necessary to add concurrency to our applications. It...