Before creating an app in Xcode it is a good idea to create a prototype app using online tools like fluidui. You can create a mocked up prototype of the app that your team can discuss, give feedback and make UI changes BEFORE you begin creation using Xcode.
a. Find online tool to create prototype. I suggest http://fluid.com b. Create prototype of app c. Share with team and discuss using a private facebook group or http://wiggio.com example: