Question

I need to parse and sort an array with 100+ entries. I have the method for parsing and sorting it below. The catch: I need it the strings stored in the NSMutableArray to be displayed in a tableView immediately when the ViewController that holds the tableView is presented/loaded. If I don’t do this, the UI hangs/freezes when invoking the ViewController. Moving the code into one of my singletons, increases boot time, which I also need to avoid.

I think I have to Queue/Block this code, but I’m not sure how to do it. Any guidance is greatly appreciated!

Here’s the code I have to parse [NSTimeZone knownTimeZones]:

-(void)parseTimeZoneNames {

    for (int i = 0; i < [[NSTimeZone knownTimeZoneNames] count]; i++) {
        NSString *fullName =  [NSString stringWithFormat:@"%@", [[NSTimeZone knownTimeZoneNames] objectAtIndex:i]];
        NSRange firstForwardSlash = [fullName rangeOfString:@"/"];
        NSRange firstNameRange = NSMakeRange(firstForwardSlash.location + 1, ([fullName length] - firstForwardSlash.location - 1));
        NSString *cityName =  [NSString stringWithFormat:@"%@", [fullName substringWithRange:firstNameRange]];

        NSRange secondforwardSlash = [cityName rangeOfString:@"/"];
        if(!secondforwardSlash.length) {

            NSRange secondNameRange = NSMakeRange(secondforwardSlash.location + 1, ([cityName length] - secondforwardSlash.location - 1));
            cityName = [NSString stringWithFormat:@"%@", [cityName substringWithRange:secondNameRange]];

        }

        NSRange underscore = [cityName rangeOfString:@"_"];
        if(!underscore.length) {

            NSRange finalNameRange = NSMakeRange(underscore.location + 1, ([cityName length] - underscore.location - 1));
            cityName = [NSString stringWithFormat:@"%@", [cityName substringWithRange:finalNameRange]];

        }

        [timeZonesArray addObject:cityName];

    }

    [timeZonesArray sortUsingSelector:@selector(compare:)];

}

Here’s the code for presenting it in the same ViewController:

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    return [[NSTimeZone knownTimeZoneNames] count];
}
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }

    cell.textLabel.text = [NSString stringWithFormat:@"%@", [timeZonesArray objectAtIndex:indexPath.row]];

    return cell;

}

Answer 1

If the code really is too slow then you can pre-sort the data yourself and add it to a plist in your app bundle.

The time zones in the world aren’t going to change. If they do, we’ve got bigger things to worry about than your app missing a few out.