The Bluetooth LE thermometer app was created as a nice display of the data from my Bluetooth Low Energy Thermometer electronic project. The app uses Ble (Bluetooth Low Energy) to connect to an AT-09 or HM-10 low energy device or similar. Once the app is connected to the Bluetooth LE thermometer device, it will start listening for serial data.
The Bluetooth LE thermometer app has a text display with a Graphical Thermometer on the thermometer page. On the Graph page, it has a text display as well as a Graphical Graph showing the last 30 data points collected from the Bluetooth Thermometer.
You can make your own Bluetooth Thermometer using the AT-09 /HM-10 Bluetooth Low Energy module and connect it to an Arduino via the UART/Serial connections. Have a look at the Bluetooth Low Energy Thermometer electronics project to see how you can make your own BLE thermometer.