In the previous article we created very simple SyncService service that can send and receive data between iOS as watch app. Which is good for very simple scenarios, but when application complexity is growing it is really important to keep you code clean, and well organized. In this article we will try to isolate sync logic from the rest of the application. In one of my project I had to synchronize data based on different events, in different part of application.

So, you have decided to create iOS application with its watch companion application. And, you need to exchange some data between two of them. For this scenario Apple provides simple WatchConnectivity framework, that specifically designed for this type of scenarios. This framework does most of the heavy lifting and your goal is simply to implement the business logic. In this article consists of two parts: Part 1. Minimum you need to sync data.