The difference between blocking UITableView or not do it

- (void)iniApp
{
    _timeLineData = [[iZ3CoreData alloc] init];
    _timeLineData.managedObjectContext = __managedObjectContext;

//    [_timeLineData syncPhotoLibrary:@"Camera Roll"];
    [_timeLineData performSelectorInBackground:@selector(syncPhotoLibrary:) withObject:@"Camera Roll"];
}