iOS is an ideal operating system for developers in this sense because it provides many services traditionally only available from middleware and typically not included in operating systems. For example, middleware related to wireless sensor network, database, media, etc. is highly relevant for m-health applications. iOS covers all of these functionalities. As discussed in Section 3, Cocoa Touch in iOS provides a number of libraries such as UIKit for interface design, CFNetwork for WiFi and cellular networking setting, and so on. These allow developers to implement sophisticated services and technologies easily without accessing lower-level layers. Of course, lower layers are still accessible when needed.