How to find out that whether a point on a map is within a radius from user's present location on iOS?

Question

I am new to iOS and I have to make an application in which the the user will know its present location and will enter a value in Kilometers and I have to find out that whether another given pair of latitude and longitude (which give a location on map) is within the given range. Please suggest if we have any function which can used to achieve this.

Answer 1

You obtain user location via CLLocationManager or via MapView's userLocation. Then you may create a CLRegion and use it's – containsCoordinate: method, like:

CLRegion* region = [[CLRegion alloc] initCircularRegionWithCenter:centerCoord radius:radius identifier:@""];
BOOL isInside = [region containsCoordinate:yourCoord]

Answer 2

- (CLLocationDistance)distanceFromLocation:(const CLLocation *)location

CLLocationDistance is a typedef for double (in meters)

Convert that to kilometers and compare it to the given value.