如何检测GPS坐标是否落在MKMapView的某个区域？

In my App i have an Array of Coordinates(CLLocationCoordinate2D) of perimeter of a circle. And now i am getting a coordinate from somewhere and i need to check if the new coordinate fall inside the circle. And if it does i just wan to show a pin on that coordinate and basically it should fall under the area. How should i go about checking this?In my App i have an Array of Coordinates(CLLoca