HM10 Bluetooth Serial iOS
This is a simple iOS 9/10 app that lets you communicate with a HM10 (or HM11 or similar) Bluetooth UART module. This way you can communicate from your iPhone/iPad with e.g. an Arduino.
It is available for free on the App Store.
The helper class for the bluetooth communication can also be found here.
A Pro version is also available on the App Store --> HM10 Bluetooth Serial Pro.
It has a tonne more features to help debugging HM10 applications, and also supports creating custom buttons to send pre-set messages.
Note: (IMPORTANT) In the preferences (within the app), select 'Write with response' if you have a fake HM10, or select 'Write without response' if you have a legit HM10 or HM11. If you don't select the right option, the app won't be able to write data to the bluetooth module. As of version 1.1.2 this is no longer needed. Writetype is now detected automatically!