Plenty of people use their iPhone or iPad to record music, livestream, and capture interviews. For better audio, you may want to invest in an XLR interface for your iOS device. These 3 XLR to Lightning audio interfaces can help:
Saramonic SmartRig+ Di: a microphone/guitar interface for recording better audio. It has two XLR microphone inputs and 2 3.5mm TRS microphone inputs. You also get a +48V Phantom power switch.
Shure MVi Digital Audio Interface: allows you to attach your iPhone, iPad directly. It supplies phantom power and 5 DSP preset modes.
Rode i-XLR: a digital interface for XLR microphones. It works with dynamic and self-powered microphones.
Which one of these have you tried? Please share your experiences here.