CLLocation方法distanceFromLocation的问题：结果不准确

I am trying to use the distanceFromLocation: method to calculate the total distance that I am walking with my iPhone in my hand. So far, I have been searching all over to help remedy my confusing, inaccurate, and seemingly arbitrary results. In these code snippets, theLabel is just a label object that is present in my app's interface, distanceMoved is the variable that I am trying to store the total distance I walked in, and locMan is a location manager that is declared in my @interface file. I am trying to use the distanceFromLocation: me