In iOS 10 you can annotate your screenshots within the Photos app, using the Markup editor.
I only found this by accident the other day, but it’s a very useful tool if you’re taking screenshots for iOS App Testing and/or Website Testing on iOS 10 devices.

Apparently, this Markup editor has been around in iOS for a while, but used to just be within the Mail app – but now it’s available in the Photos app and the Messages app.

Here’s how to use the Markup editor in Photos app

  • Take screenshot in the usual way
  • Go to Photos app
  • Select the screenshot by pressing it
  • Press the sliders icon to edit it
  • Press the circle with 3 dots inside it to choose an app/editor to edit Photo
  • Choose Markup
  • Within the Markup editor, you can choose from the following tools:
    • Brush tool – to draw on photo
    • Magnifier tool – to magnify part of the photo
    • Text tool – to add text to the photo
    • Also colour selectors, text/font tools and undo
  • With Brush tool, handy feature that allows you to make your squiggly box or circle into a proper one – ideal for highlighting part of the photo

More info on the Markup editor