GPS Tag Orange is a nice app what can turn an IOS device into a tracking unit, but it does not serve as an alternative user interface to track our devices registered with GSP-Trace orange. IMHO, such an application would be very useful, and would improve the usability of the service by a large amount what the community would pay for. Using an iPhone 5s or earlier version with Safari provides a very compromised quality of access through the online web-based interface. First, even the mobile optimized version of gps-trace.com loads very slowly, and second, the only way of receiving information from alerts is e-mail. The IOS app shall improve on both aspects, speed up and make more reliable the server connection and interface, and shall provide alerts upfront on the iPhone lock-screen through the notification centre.
An iPhone client app may talk in a device-independent manner with the server, I think no tracking device specific content is required if the server is formatting incoming messages into a unique internal format. This clould release a lot of complexity from alternative client apps and facilitate a faster development. Congrats for the good work has been done so far!