How to extract substring from a string in ios?

Question

I know this is one of the most asked question , but I am not getting how to acually do this. Here is my string ====> @"latitude - 51.50998000 , longitude - -0.13370000".

and I want to extract only the numeric values from it. How can this be achieved? Any ideas?

Answer 1

// Obtaining latitude string
NSString *locationString = @"latitude - 51.50998000 , longitude - -0.13370000";
NSRange latStringRange = NSMakeRange(11, 10);
NSString *latitudeSubstring = [locationString substringWithRange:latStringRange];
NSLog(@"Latitude substring is :- %@",latitudeSubstring);


//Obtaining longitude string
NSString *locString = @"latitude - 51.50998000 , longitude - -0.13370000";
NSRange longsStringRange = NSMakeRange(37, 10);
NSString *longSubstring = [locString substringWithRange:longsStringRange];
NSLog(@"Longitude substring is :- %@",longSubstring);

Answer 2

Not perfect solution but something to start with:

NSString *myString = @"latitude - 51.50998000 , longitude - -0.13370000";

/* Formatter is used to convert NSString to NSNumber */
NSNumberFormatter *formatter = [NSNumberFormatter new];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];

/* Predicate is used to filter array, we need only NSString values with length > 2 */
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"length > 2"];

/* Character set is used to extract only -.0123456789 characters from string */
NSCharacterSet *cSet = [[NSCharacterSet characterSetWithCharactersInString:@"-.0123456789"] invertedSet];

/* Parse latitude and longitude values to NSArray, index 0 will be latitude and index 1 will be longitude */
NSArray *values = [[myString componentsSeparatedByCharactersInSet:cSet] filteredArrayUsingPredicate:predicate];

NSNumber *latitude = [formatter numberFromString:[values objectAtIndex:0]];
NSNumber *longitude = [formatter numberFromString:[values objectAtIndex:1]];

NSLog(@"lat: %f, long: %f", [latitude doubleValue], [longitude doubleValue]);