How can I speedup list for table view?

I use some code as below to prepare list for my table view, it is very slow, is there any faster way to make list?

Code:

-(BOOL) application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
    // Override point for customization after application launch.
	NSBundle *bundle = [NSBundle mainBundle];
	NSString *filePath = [bundle pathForResource:@"index" ofType:@"txt"];
	NSString *contents = [NSString stringWithContentsOfFile:filePath encoding:NSShiftJISStringEncoding error:nil];
	NSArray *list = [contents componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];
	int i = 0;	
	
	if (list) {
		NSMutableArray *stock = [[NSMutableArray alloc] init];
	
		for (NSString *item in list) {
			if ([item length] != 0 && i != 0) {
				NSRange obs = [item rangeOfString:@"OBS"];
				
				if (obs.location == NSNotFound) {
					obs = [item rangeOfString:@"A100"];
					
					if (obs.location == NSNotFound) {
						[stock addObject:item];
					}
				}
			}
			
			i++;
		}
		
		stockSplit = stock;
	}
}

 

At the moment, I just test my logic so I put file in SandBox, in fact, this file is downloaded from Internet, so that I can't modify its format

 

No, I haven't.

 

I also think so, but I am not sure how to do it, can you tell me where I can find a useful sample for background thread?

 

Thanks for your link, it is very useful.