While Bluetooth LE does not define a standard serial protocol equivalent to the Bluetooth BDR/EDR Serial Port Protocol, a number of BTLE equivalents have been proposed. I propose that the Nordic UART Service (NUS) definition is good enough to do what you presently require of Bluetooth Classic SPP, and that the NUS could be a multi-platform-supported protocol going forward, able to run on iPhones, Androids, and other Bluetooth LE-equipped platforms such as Windows, Apple, and Linux laptops. In fact, Bluetooth LE (also called Bluetooth Smart) is the only common communication mechanism that could use a single common protocol across all devices.
Info on the protocol is available both from the Nordic website (https://devzone.nordicsemi.com/f/nordic-q-a/10567/what-is-nus-nordic-uart-service/39318 , and https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v15.2.0%2Fble_sdk_app_nus_c.html ), as well as at an Adafruit tutorial at https://learn.adafruit.com/introducing-adafruit-ble-bluetooth-low-energy-friend/uart-service
Please consider this; I think that this could offer you a clean, cross-platform, less-fiddly interface option going forward.