计算坐标数组的距离

Question

Currently I can calculate the distance between two coordinates which are NSString s.

I am now trying to calculate a list of coordinates which are in a NSMutableArray but I'm stuck.
I somehow need to calculate the distance between all loc or is there a better way of doing this?

for (int i=0; i < self.trackArray.count; i++)
{
    CGFloat latitude  = [[self.trackArray objectAtIndex:0] doubleValue];
    CGFloat longitude = [[self.trackArray objectAtIndex:1] doubleValue];

    CLLocation *loc = [[CLLocation alloc]  initWithLatitude:latitude longitude:longitude];

    CLLocationDistance distance = [loc distanceFromLocation:loc];
    CLLocationDistance kilometers = distance / 1000.0;
    self.distanceString = [NSString stringWithFormat:@"%f", kilometers];
}

Update. An example of how the array looks from the NSLog.

(
"37.335009,-122.032722",
"37.334977,-122.032813",
"37.334948,-122.032921",
"37.334922,-122.033042",
"37.334892,-122.033184",
"37.334858,-122.033344",
"37.334821,-122.033509",
"37.334780,-122.033696"
)

Sorry for not making it clear what Im trying to do, I have an app that tracks a users location and draws a line behind them, above are coordinates that were tracked from the user, I want to find the distance travelled, currently the calculated distance is as the crow fly's which is the first line of the coordinates and the last line. I want to eg calculate the distance between the first 2 lines of coordinates then add that distance to the next 2 lines of coordinates etc. So if the user walks in a circle I want to know the distance.

Answer 1

Try this:

-(void) test {
  CLLocationDistance totalKilometers = 0;
  for (int i = 0; i < (self.trackArray.count - 1); i++) // <-- count - 1
  {
     CLLocation *loc1 = [self cLLocationFromString:[self.trackArray objectAtIndex:i]];
     CLLocation *loc2 = [self cLLocationFromString:[self.trackArray objectAtIndex:(i + 1)]];

     CLLocationDistance distance = [loc1 distanceFromLocation:loc2];
     CLLocationDistance kilometers = distance / 1000.0;
     totalKilometers += kilometers;
  }
  self.distanceString = [NSString stringWithFormat:@"%f", totalKilometers];
}

-(CLLocation*) cLLocationFromString:(NSString*)string
{
    NSArray *coordinates = [string componentsSeparatedByString:@","];
    CGFloat latitude  = [[coordinates objectAtIndex:0] doubleValue];
    CGFloat longitude = [[coordinates objectAtIndex:1] doubleValue];
    return [[CLLocation alloc]  initWithLatitude:latitude longitude:longitude];
}