Convert AVMetadataItem's GPS string into a CLLocation

Question

An AVAsset (or AVURLAsset) contains AVMetadataItems in an array, of which one may be of the common key AVMetadataCommonKeyLocation.

The value of that item is a string which appears in a format like:

+39.9410-075.2040+007.371/

How do you convert that string into a CLLocation?

Answer 1

Okay I figured it out after finding that the string is in the ISO 6709 format, and then finding some relevant Apple sample code.

NSString* locationDescription = [item stringValue];

NSString *latitude  = [locationDescription substringToIndex:8];
NSString *longitude = [locationDescription substringWithRange:NSMakeRange(8, 9)];

CLLocation* location = [[CLLocation alloc] initWithLatitude:latitude.doubleValue 
                                                  longitude:longitude.doubleValue];

Here's the Apple sample code: AVLocationPlayer

Also, here's code to convert back:

+ (NSString*)iso6709StringFromCLLocation:(CLLocation*)location
{
    //Comes in like
    //+39.9410-075.2040+007.371/
    //Goes out like
    //+39.9410-075.2040/
    if (location) {
        return [NSString stringWithFormat:@"%+08.4f%+09.4f/",
            location.coordinate.latitude,
            location.coordinate.longitude];
    } else {
        return nil;
    }
}

Answer 2

I work on the same question and I have the same code in Swift without using substring :

Here the locationString is

+39.9410-075.2040+007.371/

let indexLat = locationString.index(locationString.startIndex, offsetBy: 8)
let indexLong = locationString.index(indexLat, offsetBy: 9)

let lat = String(locationString[locationString.startIndex..<indexLat])
let long = String(locationString[indexLat..<indexLong])

if let lattitude = Double(lat), let longitude = Double(long) {
      let location = CLLocation(latitude: lattitude, longitude: longitude)
}