How to dynamically sorting an NSMutableArray in Objective-C?

I am retrieving rows from SQLite table, then dynamically creating an object, and then adding the object to an NSMutableArray. My problem is that I am unable to figure out a way to dynamically sort the objects in the array based on the distance attribute (which is a double), as I am adding each object to the NSMutableArray in a for-loop, from smallest to largest.

My relevant code looks like this:

sqlite3 *database;

//Init the restaurant array
restaurants = [[NSMutableArray alloc] init];

CLLocation *firstLocation = [[[CLLocation alloc] initWithLatitude:userLatitude longitude:userLongitude] autorelease];

//Open the database from the users filesystem
if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {

    //setup the SQL statement and compile it for faster access
    const char *sqlStatement = "select * from restaurant";
    sqlite3_stmt *compiledStatement;

    if (sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {

        //loop through the results and add them to the feeds array
        while (sqlite3_step(compiledStatement) == SQLITE_ROW) {

            //read the data from the result row
            NSString *aName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)];
            NSString *aAddress = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)];
            NSString *aCity = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 3)];
  开发者_开发知识库          NSString *aProvinceState = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 4)];
            NSString *aPostalZipCode = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 5)];
            NSString *aCountry = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 6)];
            NSString *aPhoneNumber = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 7)];
            NSString *aHours = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 8)];
            double aLat = sqlite3_column_double(compiledStatement, 9);
            double aLon = sqlite3_column_double(compiledStatement, 10);

            CLLocation *secondLocation = [[[CLLocation alloc] initWithLatitude:aLat longitude:aLon] autorelease];
            CLLocationDistance restDistance = [secondLocation distanceFromLocation:firstLocation];

            CLLocationDistance distanceKm = restDistance / 1000.0;

            NSString *aDist = [[NSString alloc] initWithFormat: @"%f", distanceKm];

            Restaurant *restaurant = [[Restaurant alloc] initWithName:aName address:aAddress city:aCity provinceState:aProvinceState postalZipCode:aPostalZipCode country:aCountry phoneNumber:aPhoneNumber hours:aHours latitude:aLat longitude:aLon distance:aDist];

            //add the restaurant object to the restaurant array
            [restaurants addObject:restaurant];

            [restaurant release];

        }


    }

    sqlite3_finalize(compiledStatement);

}

sqlite3_close(database);

}

Once this function has finished its course, the restaurants array should be a sorted array containing restaurant objects that are in order of nearest (smallest distance double value) to furthest (largest distance double value).

Use NSMutableArray's sortUsingSelector to call a comparison function on your Restaurant object.

@implementation Restaurant

- (double) distance { return _distance; }

- (NSComparisonResult) compareDistance:(Restaurant *) iRHS {
    double                      lhs, rhs;

    lhs = [self distance];
    rhs = [iRHS distance];

    if ( lhs < rhs ) return NSOrderedAscending;
    if ( lhs > rhs ) return NSOrderedDescending;

    return NSOrderedSame;
}


@end

...

[restaurants sortUsingSelector: @selector(compareDistance:)];