Question

I’ve an array (tempList) populated with records read from a sqlite data source. I want to sort these records based on ‘region’. So I’ve set up the following NSMUtableArrays: _Asia, _Africa, _CentralAmerica, _southAmerica.

The method compiles without any errors. Where the ‘if’ statements return true, it executes the ‘addObject’ but the element is not added to the array.

- (void) sortIntoRegions: tempList
{
    for (beans *arrayElement in tempList) {
        NSLog(@"region: %@", arrayElement.region);
        if ([arrayElement.region isEqualToString:@"Africa"]) {
            [_africa addObject:arrayElement.name];
        } else if ([arrayElement.region isEqualToString: @"Asia & South Pacific"]) {
            [_asia addObject:arrayElement.name];           
        }
        else if ([arrayElement.region isEqualToString: @"Central America"]) {
            [_centralAmerica addObject:arrayElement];
        } else if ([arrayElement.region isEqualToString: @"South America"]) {
            [_southAmerica addObject:arrayElement];
        }
    }
}

Answer 1

I’m going to go out on a limb and guess that you have declared _africa, _asia, _centralAmerica, and _southAmerica to be NSMutableArray *, but you have not initialized them. That is, you have not written any code like this:

_africa = [[NSMutableArray alloc] init];
_asia = [[NSMutableArray alloc] init];
_centralAmerica = [[NSMutableArray alloc] init];
_southAmerica = [[NSMutableArray alloc] init];

Your instance variables are set to nil when your object is created. Sending a message (like addObject:) to nil has no effect (and doesn’t print a warning or error message).