How to reduce iPhone battery consumption when using GPS

I use GPS for actual monitoring if I entered the area (radius 100 m).

I use a hybrid of significantLocationChangehardware and the GPS, startUpdatingLocation.

Since significantLocationChangesthey are not as accurate as I require, I use them only to check if I entered the outer circle X m. Then I use hardware GPS to check if the user enters the inner circle (100 m).

The problem is that the battery runs out pretty quickly, can someone help me.