Mobile/tablet offline mockup tool

Question

I'm looking for a tool that will allow me to easily create mock ups in the go, when my internet connection is unreliable or nonexistent.

Must haves, in order of priority:

1. Create software/website UI mockups.
2. Functions without internet.
3. Platform: iOS or Android.
4. Support for common UI elements such as checkboxes, radio buttons, form input fields, etc.
5. Export as a bitmap to share with others.
6. Price: free preferred, up to £20 ok if there is a good free trial or other way to assess it first.

For bonus points:

• Cross-platform, available on both Android and iOS.
• Sync with Google Drive or Dropbox.

Answer 1

My favorite tool is OmniGraffle.

1. The advertised features of the software involve creating mockups and they provide several stencils for this purpose.

2. Functions without the internet.

3. iOS and OS X only.

4. It supports checkboxes, radio buttons, form input fields out of the box. Furthermore, it is easy to create your own custom stencils to represent anything you like.

5. It can export the document as an image for sharing.

6. It is more expensive then desired ($50), but this is a tool for professionals.

7. No built-in support for sync'ing with dropbox or google drive. They provide their own sync solution that just works.