1 can be charged with iPhone 2 Huawei p40 charger can be charged with iPhone, because the charger interface is standard USB interface, iPhone also uses USB interface to charge, so Huawei p40 charger can be charged with iPhone.
3 Different brands of mobile phone chargers can usually charge each other, as long as the interface is compatible.
So Huawei p40 charger can charge Apple phone is OK.
In addition to Huawei p40 charger, there are many chargers on the market that can be charged with Apple phones, such as Apple's own charger, Android phone charger, etc., as long as the interface is compatible, it can be used. However, it should be noted that in order to ensure the safety and effect of charging, it is recommended to use the original charger or a certified brand charger.