We used Dropsource to build our native iOS PawBoost app when we did not have the resources available to contract out development or build it ourselves.
As the non-technical half of our team, I had no problem using their editor to build out the visual side of the app. You will need a developer to format your API to Swagger specifications and hook up some logic/events in the app. However, no knowledge of Swift is required.
The Dropsource platform has improved (and continues to improve) considerably since we first started using it more than a year ago. Would definitely recommend for those seeking a low cost way to validate their big idea.