Based on our testing, you can use an external microphone with iOS devices, however the microphone must be compatible with smartphones and it must be connected by a 3.5mm TRRS AUX cable. To make that connection you will need a AUX to Lightning adapter. This allows the microphone to be registered as a "headset microphone" which can be used with StreamYard in mobile Safari.
Airpods and wired headphones with microphones will work with StreamYard on all iOS devices. Other external microphones cannot currently be used with StreamYard on iOS devices due to browser access limitations.
To use an external USB/XLR mic, we recommend using a laptop/desktop computer.