Question

This is a chat app, I’m using tableview to display the chatting data between user and others, however I’v got Rows are displayed multiple(duplicate). The code is below:

#define kMyTag 1

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{   
    NSDictionary *messageDic = [self.chatArray objectAtIndex:indexPath.row];
    if ([[messageDic objectForKey:@"myself"]boolValue] == false) {
        static NSString *CellIdentifier = @"MessageChatFriendCell"; 
        MessageChatFriendCell *cell = (MessageChatFriendCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[MessageChatFriendCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
        }
        NSDictionary *chatInfo = [self.chatArray objectAtIndex:[indexPath row]];
        UIView *chatView = [chatInfo objectForKey:@"view"];
        chatView.tag = kMyTag;
        [cell.contentView addSubview:chatView];
        return cell;
    } else  {
        static NSString *CellIdentifier = @"MessageChatSelfCell";
        MessageChatSelfCell *cell = (MessageChatSelfCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[MessageChatSelfCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
        }
        NSDictionary *chatInfo = [self.chatArray objectAtIndex:[indexPath row]];
        UIView *chatView = [chatInfo objectForKey:@"view"];
        chatView.tag = kMyTag;
        [cell.contentView addSubview:chatView];
        return cell;
    }
}

the print results for each row are:

2012-08-02 15:44:47.152  MessageChatSelfCell-><UIView: 0x222790; frame = (85 0; 230 114); tag = 1; layer = <CALayer: 0x222320>>
2012-08-02 15:44:47.166  MessageChatFriendCell-><UIView: 0x21d790; frame = (0 0; 210 132); tag = 1; layer = <CALayer: 0x21d5c0>>
2012-08-02 15:44:47.176  MessageChatFriendCell-><UIView: 0x21bde0; frame = (0 0; 177 60); tag = 1; layer = <CALayer: 0x21be10>>
2012-08-02 15:44:47.183  MessageChatSelfCell-><UIView: 0x216430; frame = (85 0; 230 168); tag = 1; layer = <CALayer: 0x215fc0>>
2012-08-02 15:44:59.232  MessageChatFriendCell-><UIView: 0x215150; frame = (0 0; 86 60); tag = 1; layer = <CALayer: 0x214eb0>>
2012-08-02 15:45:00.465  MessageChatSelfCell-><UIView: 0x213220; frame = (85 0; 230 78); tag = 1; layer = <CALayer: 0x213250>>

Please advise, thanks!

Updated 2012-08-08

#define WRITER_NAME_LABEL_TAG 4
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{   
    static NSString *MessageChatSelfCellIdentifier = @"MessageChatSelfCell";    
    static NSString *MessageChatFriendCellIdentifier = @"MessageChatFriendCell";
    UITableViewCell *cell = nil;
    UIView *chatView = nil;
    NSDictionary *messageDic = [self.chatArray objectAtIndex:indexPath.row];
    NSString *text = [messageDic objectForKey:@"compiled"];
    BOOL myMessage = [[messageDic objectForKey:@"myself"] boolValue];

    if (myMessage) {
        cell = [tableView dequeueReusableCellWithIdentifier:MessageChatSelfCellIdentifier];

        if(cell == nil) 
        { 
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
                                           reuseIdentifier:MessageChatSelfCellIdentifier];

        chatView = [self bubbleView:[NSString stringWithFormat:@"%@", text] 
                                       from:YES];
        chatView.tag = WRITER_NAME_LABEL_TAG;
        NSLog(@"MessageChatFriendCell->%@",chatView);
        [cell addSubview:chatView];
        }else {
            chatView = (UIView *)[cell viewWithTag:WRITER_NAME_LABEL_TAG];
        }
    } else  {
        cell = [tableView dequeueReusableCellWithIdentifier:MessageChatFriendCellIdentifier];

        if(cell == nil) 
        { 
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
                                          reuseIdentifier:MessageChatFriendCellIdentifier];

        NSString *text = [messageDic objectForKey:@"compiled"];        
        UIView *chatView = [self bubbleView:[NSString stringWithFormat:@"%@", text] 
                                       from:NO];
        chatView.tag = WRITER_NAME_LABEL_TAG;
                NSLog(@"MessageChatSelfCell->%@",chatView);
        [cell addSubview:chatView];
        }else {
            chatView = (UIView *)[cell viewWithTag:WRITER_NAME_LABEL_TAG];
        }
    }  
        return cell;
}

Answer 1

I answered your another question How to calculate the Width and Height of NSString on UILabel

They are similar problem. the code below I C&P from the other question.

That’s because you did not reuse the table cell, the structure should be like:

NSString *text = [messageInfo objectForKey:@"compiled"];
if(cell == nil) 
        { 
     writerNameLabel.numberOfLines = 0;
     writerNameLabel.textAlignment = UITextAlignmentRight;
     writerNameLabel.backgroundColor = [UIColor clearColor];
     [cell addSubview:writerNameLabel];
}
else {
     writerNameLabel = (UILabel *)[cell viewWithTag:WRITER_NAME_LABEL_TAG];
}
CGSize constraint = CGSizeMake(296,9999);
CGSize size = [text sizeWithFont:[UIFont systemFontOfSize:FONT_SIZE] 
               constrainedToSize:constraint 
                   lineBreakMode:UILineBreakModeWordWrap];
[writerNameLabel setFrame:CGRectMake(writerNameLabel.frame.origin.x, writerNameLabel.frame.origin.y, size.width, size.height)];

I’ve been gone through and answered some of your question, that’s correct way to write your tableview controller. And your problem will be solved.