//1.将两个经纬度点转成投影点
MAMapPoint point1 = MAMapPointForCoordinate(CLLocationCoordinate2DMake(39.989612,116.480972));
MAMapPoint point2 = MAMapPointForCoordinate(CLLocationCoordinate2DMake(39.990347,116.480441));
//2.计算距离
CLLocationDistance distance = MAMetersBetweenMapPoints(point1,point2);