On the Codete Blog website you can find my new article about implementing web-services in Swift.

(…) Usually, when designing communication between a server and an iOS application, we choose JSON as a default serialization method. It has a lot of advantages: readability, flexibility and good availability of serializers in the majority of most popular web technologies used.
In most cases it is sufficient to use JSON, but when we want to send a lot of data in one shot or our services generate a lot of traffic, it can be reasonable to replace JSON with a more efficient method.

Read more on Codete Blog: High performance web services with Swift and Protocol Buffers.