In recent years, with the accelerated pace of social life, people's living standards have been improved. The constant updating of things has kept people in the pursuit of fashion, a phenomenon that is evident in young groups. For the items that have been changed, they are often shelved or discarded, and the value of the goods is not fully represented. Therefore, it is very important to reuse the second-hand goods. Under the premise of the rapid development of modern mobile Internet technology, mobile devices have added more and more convenience and fun to our life. Now there are many secondary item trading software on the software market, but there is no one suitable for the user's real requirements of the product free sharing platform. The user's needs and experience play an indispensable role in the function of app. On this basis, we design an iOS mobile phone application based on the user's demand analysis and mobile application experience, which is the main function of commodity presentation and exchange. The purpose of this study is to have the goods idle and second-hand goods needs of the user to provide a platform for free and mobile users, the Internet technology and the demands of daily life with convenient goods maximum value. On the Mac platform, the design and implementation of APP functions are displayed on the iOS mobile phone terminal, and the implementation principle and related features of iOS system software are analyzed, which reflects the theme that science and technology can make human life better.