This a serial monitor that can send strings in UTF-8 between an IOS device and an device equipped with Nordic nRF BLE Bluetooth modules that are used with the Espressif ESP32 and Arduino Nano ESP32, MKR1010, Nano BLE 33 et cetera.
An BLE explanation and Arduino example program here
Several Arduino source codes are here or on Github/ednieuw that utilises this app.
This free app can be found here in the Apple app store : BLESerial nRF in de App Store.
This app is identical with the the BLE serial Pro app but the functions TAB will not work.
It's working can be found on this page: BLE serial Pro app
Behind the function TAB buttons can be created that will send a string of commands
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