Build mobile app for multiple platforms

I require the following app features, in both Android and iOS platforms. The app will be used by individuals. The app:- - is required for people that are attending 'events' (think small events attended by individuals with a particular commonality) - will allow for profiles to be created, including individualdetails (names, ages, features etc) including adding of photos from the user's device, and taking of photos. Video not required. - will allow for multiple events to be added, including details such as dates of the events, locations, contact details for event co-ordinators - will allow for some or all profiles to attend each event on the device - will allow for event dates to be integrated (added, removed) with the OS's default calendar app, and for event locations/addresses to be integrated with the OS's default navigation app. - Details specific to the profile and event must be able to be added after the event. These details must be viewable within the profile summary (Summary of all event info collated and/or displayed in the profile) - Integration with social media required. Preferable to include facebook 'events' being able to be added as an event within the app. A 'notify facebook' link to post to a user's facebook profile that they are attending an event (including the name of the app in the post) would be required also. This would advertise the app among their friends. - does not need to link to cloud services, however a registration system (username/password) is required to allow for saving and security of details. It would also allow portability for a user to use multiple devices for their account/information. - may have (optional) a web interface for easier updating of their event/profile information using a desktop or laptop computer. I have some design ideas which can be clarified with shortlisted app developers, however your design ideas are required before a decision can be made for the secussful developer. Note that this is the first of several app ideas, and successful app developers that impress me will gain automatic (non-competitive) approach for future apps. I.e. this app will potentially lead to further work.