Write an iPhone application - General Consumer

We are a looking for creative input to developing a SIMPLE general consumer app. We have a patented platform that food trucks operate from which is highly integrated to social media and has a database of 10,000s of food trucks. We also have their location via apple ibeacon or android location announcements with push technology to announce open and serving with a native map integration. We want to use this to launch a consumer app to help people find a food truck open on the foosye platform near their location (say 10 miles) and for push notification of their favorite or geo-close trucks when they announce open or closed for business at a location. People also need to use the app to sort for menu / food & beverage or desert options. They should be able to contact the truck through foosye app via the platform and the vendor ID they have as this shows on their notifications. Example would be I am with my friends and we want to find a food truck with hibachi and one with burritos near our location. If we like the truck we want to save to our favorites so we are notified of their activities on the platform through alerts and notifications on the foosye app. We currently have 3 apps for the vendor side and to hire a food truck all built on Xamarin and are looking to perhaps have this app also build on Xamarin so it can be replicated some for both iOS and Android. Looking for a freelancer(s) who have experience with building engaging and notification apps that are simple, clean and fun. We would like for people to pay at some point by having an account on the app and using our Stripe and Square partnerships to order via the app and pay via intra-app (new Stripe feature). These can be build into future builds, so yes we are looking to retain people to help in the evolution of the foosye suite of products. A plus is creative approach and ideas. We built a gaming app with badges and points which was a hit and looking for some crowdsourcing of trucks we do not have and a way for the consumer to add them perhaps and get $ back for a food truck meal or a badge, etc. Foosye has all the color schemes, trademarked logos and full dev ops team and marketing to help in the final massage of the product so we are looking for BOTH COST AND SPEED on this project to help propel our progress in other areas right now. Questions are welcomed, again looking at time to complete and fixed (lower) costs on this first build. Thank you!