Currently, there are 4 standards for wireless charger.
QI, PMA, A4WP, INPOFI. For Apple, they use QI standard for AirPower .
Qi wireless charger system is made of base station and movable device.
Base station is the charging bottom, movable device is the mobile.
The magnetic induction coil of Charging bottom transfers the electricity power to the battery wave, The magnetic induction coil of the mobile back cover transfers the battery wave to electricity power to charge.
Currently the wireless charger shortage is the charging effectiveness.
We still need to work the quicker solution of it.