| With the rapidly development of Mobile Internet and the popularity of smart phones, people are enjoying the ease and convenience that brought by Mobile Internet. As the most popular way of communication between people, instant messaging is gradually transplanted into this emerging platform, becoming one of the greatest demand applications.Therefore, we develop a application based on iOS including the client and the server. The thesis focuses on the design and implementation of the client system. The client system consists of the main modules:the chatting module, the contact module, the friends and the setting module. The problem of streaming media compression is also deeply studied. In order to decouple each module and increase the system flexibility and extensibility, Cocoa Touch framework and some design patterns are applied. We apply the XMPP communication protocol to connect the client the server, and apply real-time XML compression algorithm to save the traffic. We apply the multi-threading technology to improve the speed of image transmission and the notification of message,Finally, we build a platform for the testing work and draft all the test cases.The test results indicate that the system has complete and stable functions as well as friendly and concise user interface. It basically meets the quality requirements of the iOS-based instant messaging system. |