Inconsistent floating point conversion behavior between GET and POST requests under iOS 11.x

[lhasiuk]

The following code snippet reveals interesting behavior under iOS 11 (but not iOS 10):

        double lat = 47.6024947;
        double lon = -122.3379909;

        NSDictionary *params = @{ @"lat": @(lat) , @"lon": @(lon) }];
        NSMutableURLRequest *request = [objectManager requestWithObject:nil method:RKRequestMethodPOST path:@"/path" parameters:params];
        NSLog(@"%@: %@, body %@", request.HTTPMethod, request.URL.absoluteString, [[NSString alloc] initWithData:request.HTTPBody encoding:NSUTF8StringEncoding]);
        request = [objectManager requestWithObject:nil method:RKRequestMethodGET path:@"/path" parameters:params];
        NSLog(@"%@: %@", request.HTTPMethod, request.URL.absoluteString);

Result:
POST: https://api.host.com/path, body {"lat":47.602494700000001,"lon":-122.33799089999999}
GET: https://api.host.com/path?lat=47.6024947&lon=-122.3379909

Under iOS 10.x the POST body's "lat" and "lon" values match those seen in the GET URI and the values originally assigned to the "lat" and "lon" doubles, i.e.:
POST: https://api.host.com/path, body {"lat":47.6024947,"lon":-122.3379909}
GET: https://api.host.com/path?lat=47.6024947&lon=-122.3379909

I have a workaround where I use NSDecimalNumbers in the params dictionary, instead of NSNumbers, but the behavior still seems wrong to me. Whatever conversion method is used in building the JSON should match what's used when building the URI parameters.