CODEWITHSUNDEEP
iphonecocoa-touchmath
Lee Armstrong
Lee Armstrong

Reputation: 11452

Get New Co-Ordinate based on degrees and distance

I have a coordinate from Core Location and want to calculate the co-ordinate given a bearing and a distance, say in km.

I think this is the formula from here. http://www.movable-type.co.uk/scripts/latlong.html

Formula:
lat2 = asin(sin(lat1)*cos(d/R) + cos(lat1)*sin(d/R)*cos(θ))
lon2 = lon1 + atan2(sin(θ)*sin(d/R)*cos(lat1), cos(d/R)−sin(lat1)*sin(lat2))
d/R is the angular distance (in radians), where d is the distance travelled and R is the earth’s radius

I have the following code.

     CLLocationCoordinate2D linecoordstart;
     linecoordstart = [[existingpoints objectAtIndex:i] coordinate];
     NSString *bearing = [[existingpoints objectAtIndex:i] heading];
     NSString *distance = [[existingpoints objectAtIndex:i] distance];
CLLocationCoordinate2D sourceCoordinate;
                sourceCoordinate = [[existingpoints objectAtIndex:i] coordinate];


NSLog(@"%f,%f",sourceCoordinate.latitude,sourceCoordinate.longitude);
   float lat2;
int d = 5;
int R = 6371;
lat2 = asin(sin(sourceCoordinate.latitude)cos(d/R) + cos(sourceCoordinate.latitude)sin(d/R)cos(180));
NSLog(@"%f",lat2);

I want to be able to pass it a bearing which is currently an NSString and the distance. I cannot work out how to use the Math.h functions for the life of me!

Upvotes: 0

Views: 304

Answers (1)

Ramin
Ramin

Reputation: 13433

To convert from NSString to a number you can use:

NSString* intNum = @"123";
NSString* floatNum = @"123.456";
int iv = [intNum intValue];
float fv = [floatNum floatValue];

Also, both d and R are defined as int (instead of float). In your code d/R will clip the value to integer 0. Might want to make them float (and initialize them with float values).

Upvotes: 1

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