How to calculate distance between two places? Is there any service available by Google Map for iphone?

I want to put facility to display distance between two places sele开发者_StackOverflow中文版cted by user.

Is there any sample source code / service available to do so?

Thanks in advance.

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The CoreLocation Framework provides the capability to work out the distance, in meters, between two points:

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

You can initialize a CLLocation object with latitude and longitude:

- (id)initWithLatitude:(CLLocationDegrees)latitude longitude:(CLLocationDegrees)longitude

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If you have two CLLocation objects, you can just do:

[location1 getDistanceFrom:location2];

However, that's just point-to-point. If you want the distance over a specific route, well, that's a whole other kettle of fish.

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This is a task for CLLocation framework. With known coordinates of 2 points you can create (if you don't have them already) 2 CLLocation objects and find a distance between them using

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

method.

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I am not familiar with iPhone development, but here is the C# code for computing the distance between two points using the Haversine formula:

/// <summary>
/// Computes the distance beween two points
/// </summary>
/// <param name="P1_Latitude">Latitude of first point (in radians).</param>
/// <param name="P1_Longitude">Longitude of first point(in radians).</param>
/// <param name="P2_Latitude">Latitude of second point (in radians).</param>
/// <param name="P2_Longitude">Longitude of second point (in radians).</param>
protected double ComputeDistance(double P1_Longitude, double P1_Latitude, double P2_Longitude, double P2_Latitude, MeasurementUnit unit)
{            
    double dLon = P1_Longitude - P2_Longitude;
    double dLat = P1_Latitude - P2_Latitude;

    double a = Math.Pow(Math.Sin(dLat / 2.0), 2) +
            Math.Cos(P1_Latitude) *
            Math.Cos(P2_Latitude) *
            Math.Pow(Math.Sin(dLon / 2.0), 2.0);

    double c = 2 * Math.Asin(Math.Min(1.0, Math.Sqrt(a)));
    double d = (unit == MeasurementUnit.Miles ? 3956 : 6367) * c;
    return d;

}

The MeasurementUnit is defined as:

/// <summary>
/// Measurement units
/// </summary>
public enum MeasurementUnit
{
    Miles,
    Kilometers
}

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It depends on which kind of difference you wanna have between both points. On the map I think you dont wanna the air distance. Then you should check http://iosboilerplate.com/

If you still wanna use the air distance, use Core Location.

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

Returns the distance (in meters) from the receiver’s location to the specified location. (Deprecated in iOS 3.2. Use the distanceFromLocation:

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