This paper describes the knowledge of memory management and cache of iOS development in detail, and introduces methods of debugging memory problems using tools which is provided by Apple IDE Xcode, for the memory problems when UITableView contains large amounts of network pictures, with the goal of memory optimization and best user experience. It proposed network of asynchronous-download pictures and the local cache solution. Finally, test results show that the memory allocation is safe and stable, the app runs more smoothly, and have a better user experience.