The app I used to solve my quandary is Skitch, free from the Apple App store for iPhone and iPad.

At one time Skitch was probably the best screenshot tool for Mac OS X. A recent update for its Mac version made the tool unresponsive and worst of all, removed many of the features long time users had become accustomed to. Last year Skitch was purchased by cloud productivity company Evernote, which has since been on a mission to integrate the tool into its cloud document platform.

Where the Mac version frustrates users with its sparseness, the Skitch apps benefit from the minimalism.

A tool drawer that's hidden away until needed, and an undo button is the sum total of the working area on Skitch.

Tools include arrows, text, shapes, and highlighting. The size and colour of the tools are controlled by a palette located in the drawer.