The best app ideas don’t necessarily come from the ranks of iOS (s aapl) developers. Anyone can have a good idea for a new app. The challenge is in getting that new idea down in a way that makes it easy to share and visualize. For both developers and non-developers alike, the App Store has a selection of design tools for the iPad that each play a unique role in the process of evolving a good idea into a great one.
UI Sketcher ($3.99) — In the “better than a bar napkin but still sort of a bar napkin” category, there’s UI Sketcher. In this app, all you get is virtual graph paper and a selection of five different pens. If you want to pass around an iPad for a rapid session of brainstorming, then a free form based designer like UI Sketcher is the best choice. I would recommend investing in a stylus like the Pogo Sketch or the upcoming Cosmonaut to help your inner artist become more of a professional draftsman than a kindergarden finger painter.
Mocking Pad ($9.99) — Mocking Pad represents a step up from free form design. There is a lot to be said about keeping the initial design as loose as possible, meaning you probably don’t want to spend a lot of time on color choices, pixel perfect button placement, or even the exact implementation of which widget to use. This designer is that you have a pallet of roughed out widgets to choose from. You drag and drop each widget onto a sketched outline of an iPhone or iPad screen. The number of controls at you disposal is not limitless, but more than adequate to get the idea across. This is a very good design tool to use early in the design process to work out user interaction scenarios and screen level functionality without getting too caught up in the overall look and feel of the final product.
Blueprint ($14.99) — This is the Rolls-Royce of designers. As with Mocking Pad, you’re presented with a pallet based drag and drop design interaction. Where this differs from Mocking Pad is that the controls are almost an exact replica of the final product. It can therefore provide pixel-perfect alignment of each element in your application. This tool is most useful in the development of a high-level storyboard of the app. You can see the entire navigation of the app you’re creating from one comprehensive view. If you are not a developer, and you what a way to quickly piece together a story board of exactly how you want the application to work, then this is the choice for you. If you are a developer, you may find that time is better spent on creating a series of well drafted XIB files in Xcode. Then take some screen shots of the XIBs in Xcode’s designer to piece together in some sort of page layout tool, so you aren’t duplicating effort.
Runners Up — Draft from 37signals is a good alternative to UI Sketcher as a free hand designer. It’s worth considering if you’re already a Campfire (web-based chat client) user, as the designs can be shared with your fellow campers from within the app. iMockUps were both good alternatives for Mocking Pad, and are worth a second look if you decide that Mocking Pad is not right for you in this space. I have found no replacement or competition for Blueprint. For what it has to offer, there is simply nowhere else to look.
Each design tool has its niche. I would recommend UI Sketcher to get that initial idea down before you forget it. Once you have a good idea and are ready to think through some basic user interaction scenarios, then Mocking Pad will prove to be the tool you need. I would avoid using a tool like Blueprint at first, as it has the potential to consume a lot of time and could limit your implementation choices when handing your design over to the development team. On the other hand, if you are not at all technically-oriented and really want to get as close to a final design as possible before you hand it over, then Blueprint is a great tool to work with and has no match.