Question

I need to extract the different components from a GPS coordinate string. So for example:

+30° 18' 12" N  // pull out 30, 18 & 12

or

+10° 11' 1" E    // pull out 10, 11 & 1

or

-3° 1' 2" S    // pull out -3, 1 & 2

or

-7° 12' 2" W    // pull out -7, 12 & 2

I have had a look around online and I notice there is the NSRegularExpression. I was wondering if it’s possible to use this in some way? I have also had a look at the documentation provided and I have tried to put together a regex to pull out the different parts. This is what I came up with:

('+'|'-')$n°\s$n'\s$n"\s(N|E|S|W)

I’m not really sure if this is correct or not, I’m also unclear on how to use it since there aren’t many tutorials/example around. Please could someone help me out? If there is a better way of doing this rather than using NSRegularExpression I’m open to it, however as far as I’m aware objective c does’t have any built in regex support.

Answer 1

Using NSScanner:

NSScanner *scanner;
NSCharacterSet *numbersSet = [NSCharacterSet characterSetWithCharactersInString:@" °'"];
int degrees;
int minutes;
int seconds;

NSString *string = @" -7° 12' 2\" W";
scanner = [NSScanner scannerWithString:string];
[scanner setCharactersToBeSkipped:numbersSet];
[scanner scanInt:&degrees];
[scanner scanInt:&minutes];
[scanner scanInt:&seconds];
NSLog(@"degrees: %i, minutes: %i, seconds: %i", degrees, minutes, seconds);

NSLog Output:

degrees: -7, minutes: 12, seconds: 2