Develop a Mac Application

I am testing the waters here, I would like to develop a MVP of a stock taking application that can work on an iPhone or iPad. The app will ultimately be for the restaurant and hospitality business, for business owners to effortlessly be able to take stock of their food and beverage themselves. Once the MVP is built and I can find some adopters who will use the product, I then want to develop it more, hence it is starting as a very small project, but I would ultimately see it as being a very valuable tool for restaurants, caterers and other hospitality professionals. I envisage using pictures for the bottles of alcohol and using a slider system that will work with a clock dial or slider to move up or down till it reaches the volume on the bottle, and then by mathematical calculation it will work out the volume in the bottle. So, the bar manager can then enter, he has 4.65 bottle of Gin or vodka etc. I expect to start with alcohol first and then move into food thereafter, and lastly consumables. I would then like to ultimately have the app capture the data from invoices and pricing and produce a product/food cost and then a GP. I hope this makes sense, I am happy to give diagrams, sketches and drawing to further explain to potential developers who might be interested to work on this project. Regards, Alan