How to dynamically sorting an NSMutableArray in Objective-C? - iphone

Question

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)];
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).

Answer 1

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:)];