CODEWITHSUNDEEP
iosobjective-c
redoc01
redoc01

Reputation: 2307

iOS, UITableView flashing after i reload new data

Whats Happening

I have a UITableView, what i do is display the first ten records from the database then when the user scrolls to the end i retrieve just one record from the database and then add this to the array and reload the data but the UITableView seems to flash. I have added some code that will sync the data correctly so that when i scroll down and retrieve the record i don't get duplicate data.

Question

How can i stop the flashing or flickering when i add new data to the UITableView?

CODE

This is where i add the new data when i scroll down to the bottom:

            -(void)renderScrollThreadInfo:(NSDictionary*)dic{

            NSDictionary *thread = [dic objectForKey:@"thread"];


            if((NSNull*)thread != [NSNull null]){

            int t_ID;
                int t_U_ID;
                int t_C_ID;
                NSString *t_Name;
                NSString *t_Description;
                NSDate *t_Created;
                int t_Flagged;
                int t_Rated;
                NSString *firstName;
                NSString *lastName;
                NSString *categoryName;

                for(NSDictionary *dict in thread)
                {
                if((NSNull *)[dict objectForKey:@"T_ID"] != [NSNull null]){
                t_ID = [[dict objectForKey:@"T_ID"] intValue];
                }
                if((NSNull *)[dict objectForKey:@"T_U_ID"] != [NSNull null]){
                t_U_ID = [[dict objectForKey:@"T_U_ID"] intValue];
                }
                if((NSNull *)[dict objectForKey:@"T_C_ID"] != [NSNull null]){
                t_C_ID = [[dict objectForKey:@"T_C_ID"] intValue];
                }
                if((NSNull *)[dict objectForKey:@"T_Name"] != [NSNull null]){
                t_Name = [dict objectForKey:@"T_Name"];
                }
                if((NSNull *)[dict objectForKey:@"T_Description"] != [NSNull null]){
                t_Description = [dict objectForKey:@"T_Description"];
                }
                if((NSNull *)[dict objectForKey:@"T_Created"] != [NSNull null]){
                NSString *timestampString = [dict objectForKey:@"T_Created"];
                double timestampDate = [timestampString doubleValue];
                t_Created = [NSDate dateWithTimeIntervalSince1970:timestampDate];
                }
                if((NSNull *)[dict objectForKey:@"T_Flagged"] != [NSNull null]){
                t_Flagged = [[dict objectForKey:@"T_Flagged"] intValue];
                }
                if((NSNull *)[dict objectForKey:@"T_Rated"] != [NSNull null]){
                t_Rated = [[dict objectForKey:@"T_Rated"] intValue];
                }
                if((NSNull *)[dict objectForKey:@"U_FirstName"] != [NSNull null]){
                firstName = [dict objectForKey:@"U_FirstName"];
                }
                if((NSNull *)[dict objectForKey:@"U_LastName"] != [NSNull null]){
                lastName = [dict objectForKey:@"U_LastName"];
                }
                if((NSNull *)[dict objectForKey:@"C_Name"] != [NSNull null]){
                categoryName = [dict objectForKey:@"C_Name"];
                }

                ThreadInfo *threadObj = [ThreadInfo new];
                threadObj.iD = t_ID;
                threadObj.userId  = t_U_ID;
                threadObj.catId = t_C_ID;
                threadObj.name = t_Name;
                threadObj.description = t_Description;
                threadObj.timeStampCreated = t_Created;
                threadObj.flagged = t_Flagged;
                threadObj.rated = t_Rated;
                threadObj.firstName = firstName;
                threadObj.lastName = lastName;
                threadObj.category = categoryName;

                BOOL foundThreadId = false;

                for(int i = 0; i < [threadsArray count] - 1; i++){
                ThreadInfo *tmpThreadInfo = (ThreadInfo*)[threadsArray objectAtIndex:i];
                if(tmpThreadInfo.iD == t_ID){
                    foundThreadId = true;
                }
                }

                if(!foundThreadId){
                [threadsArray addObject:threadObj];
                }



            }
            [tableViewThreads reloadData];
            }

        }

This is the code that calls a php script to get the next record:

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
        {
            if(tableViewThreads == tableView){
            //NSLog(@"%d %d",[indexPath row], [threadsArray count] - 1);
            if ([indexPath row] == [threadsArray count] - 2) {

                ThreadInfo *threadInfo = (ThreadInfo*)[threadsArray objectAtIndex:[threadsArray count] - 1];
                int tid = threadInfo.iD;


                dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

                // 3) Load picker in background
                dispatch_async(concurrentQueue, ^{


                NSString *searchItem = textFieldSearchThreads.text;
                NSString *myRequestString = [NSString stringWithFormat:@"Category=%d&TID=%d&SearchItem=%@",rowCategory, tid, searchItem];
                NSString *response = [self setupPhpCall:myRequestString :@"getThread.php"];


                dispatch_async(dispatch_get_main_queue(), ^{

                    if(response.length > 0){
                    [self renderScrollThreadInfo:[response JSONValue]];
                    }

                });

                });
            }
            }

            if(tableViewPosts == tableView){
            //NSLog(@"%d %d",[indexPath row], [threadsArray count] - 1);
            if ([indexPath row] == [postsArray count] - 1) {

                PostInfo *postInfo = (PostInfo*)[postsArray objectAtIndex:[postsArray count] - 1];
                int pid = postInfo.iD;


                dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

                // 3) Load picker in background
                dispatch_async(concurrentQueue, ^{


                NSString *myRequestString = [NSString stringWithFormat:@"TID=%d&PID=%d", chatThreadId, pid];
                NSString *response = [self setupPhpCall:myRequestString :@"getStandalonePost.php"];


                dispatch_async(dispatch_get_main_queue(), ^{

                    if(response.length > 0){
                    //[tableViewPosts scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:NO];
                    [self renderScrollPostInfo:[response JSONValue]];
                    }

                });

                });
            }
            }
        }

This is the code where a set up my Custom Cells with data:

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {


            if(tableViewThreads == tableView){
            NSString *cellIdentifier = @"cell";
            ThreadTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];


            ThreadInfo *threadInfo = (ThreadInfo*)[self.threadsArray objectAtIndex:indexPath.row];;
            if (cell == nil)
            {
                cell = [[ThreadTableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];

                [cell setupView:threadInfo];

            }


            cell.labelFirstName.text = [NSString stringWithFormat:@"%@ %@", threadInfo.firstName,threadInfo.lastName];

            cell.labelTimestamp.text = [NSDateFormatter localizedStringFromDate:threadInfo.timeStampCreated dateStyle:NSDateFormatterMediumStyle timeStyle:NSDateFormatterMediumStyle];
            cell.labelTimestamp.text = [cell.labelTimestamp.text stringByReplacingOccurrencesOfString:@"AM" withString:@""];
            cell.labelTimestamp.text = [cell.labelTimestamp.text stringByReplacingOccurrencesOfString:@"PM" withString:@""];

            cell.labelThreadName.text = threadInfo.name;
            //cell.selectionStyle = UITableViewCellSelectionStyleNone;
            return cell;

            }
            if(tableViewPosts == tableView){
            NSString *cellIdentifier = @"cell2";
            PostTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];

            PostInfo *postInfo = (PostInfo*)[self.postsArray objectAtIndex:indexPath.row];
            if (cell == nil)
            {
                cell = [[PostTableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];

                [cell setupView:postInfo];
            }



            cell.labelUserName.text = [NSString stringWithFormat:@"%@ %@ posted...", postInfo.firstName,postInfo.lastName];
            cell.labelCreated.text = [NSDateFormatter localizedStringFromDate:postInfo.timeStampCreated dateStyle:NSDateFormatterMediumStyle timeStyle:NSDateFormatterMediumStyle];
            cell.labelCreated.text = [cell.labelCreated.text stringByReplacingOccurrencesOfString:@"AM" withString:@""];
            cell.labelCreated.text = [cell.labelCreated.text stringByReplacingOccurrencesOfString:@"PM" withString:@""];
            cell.labelMessage.text = postInfo.message;
            return cell;
            //[cell.contentView addSubview:[self setupThreadItem:threadInfo]];
            }

            return nil;
        }

Upvotes: 1

Views: 1146

Answers (1)

David Berry
David Berry

Reputation: 41226

Instead of calling [UITableView reloadData] when you receive new data, use [UITableView insertRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation

Upvotes: 3

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