How to get cell in heightForRowAtIndexPath?

Question

I have created custom cells in my app.I want to get the each cell in HeightForRowAtIndexPath.Please tell me how can i get the custom cell in this method.I have tried this code but this causes infinite loop & finally crash the app.

HomeCell *cell=(HomeCell *)[tableView cellForRowAtIndexPath:indexPath];

EDIT:

I Have tried this but it gives me cell height as zero.

-   (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *cellIdentifier = @"HomeCell";
    HomeCell *cell = (HomeCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

    float tv_view_height=cell.tv_post.frame.size.height;
    float like_count_height=cell.label_like_count.frame.size.height;
    float first_comment_height=cell.first_comment.frame.size.height;
    float second_comment_height=cell.second_cmment.frame.size.height;
    float third_comment_height=cell.third_comment.frame.size.height;

    Post *user_post=[arr_post objectAtIndex:indexPath.row];
    float comment_count=[user_post.comment_count intValue];
    if(comment_count<=0)
    {
        first_comment_height=0;
        second_comment_height=0;
        third_comment_height=0;


    }
    else if(comment_count==1)
    {
        second_comment_height=0;
        third_comment_height=0;

    }
    else if(comment_count==2)
    {

        third_comment_height=0;
    }
     float like_count=[user_post.like_count intValue];
    if(like_count<=0)
    {

        like_count_height=0;
    }
    float total_height=tv_view_height+like_count_height+first_comment_height+second_comment_height+third_comment_height;
    NSLog(@"total heigh is %f'",total_height);
    return total_height;
}

Please tell which is the best way?

using `dequeueReusableCellWithIdentifier` inside `heightForRowAtIndexPath` is not a good idea. — 0yeoj, Oct 20 '15 at 08:46
Can you let us know wt do u want to achieve.. Y u want to get cell in heightForRowAtIndexPath.. ?? — luckyShubhra, Oct 20 '15 at 09:00
agree with @0yeoj, you can try keep track of the heights of cell in `- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath` with `indexPath.row` as key in a `NSDictionary`, then get the heights in heightForRowAtIndexPath — Francis Yeap, Oct 20 '15 at 09:02
You're always setting your heights to zero, isnt' that your problem? — Gil Sand, Oct 20 '15 at 09:19
there are a lot of approach to compute the height, i suggest you compute the height without using `dequeueReusableCellWithIdentifier`, something like computing the height of the label based from the text in indexPath plus all the space inside the cell (eq. margin/spacing) — 0yeoj, Oct 20 '15 at 09:48
You need to change the height if you need several heights depending on data shown by each cell. If this is the case you can store the data you are going to use in arrays, and index those arrays via the indexPath parameter (which gives you row and section components). Then determine what height you are going to need based on your data, as the cell itself has not been created yet, as pointed out in answer by ifau. - You can use autolayout as well. — Michele Giuseppe Fadda, Oct 20 '15 at 12:38

score 17 · Answer 1 · answered Oct 20 '15 at 11:03

How to get cell in heightForRowAtIndexPath?

It's impossible, because when -heightForRowAtIndexPath is called, no cells are created yet. You need to understand how the UITableView works:

UITableView asks it's datasource how many sections it will have

-numberOfSectionsInTableView

At this point there are no cells created.
UITableView asks it's datasource how many rows each section will have

-numberOfRowsInSection

At this point there are no cells created.
UITableView asks it's delegate height of each visible row, to know where cells will be located

-heightForRowAtIndexPath

At this point there are no cells created.
UITableView asks it's datasource to give it a cell to display at given index path

-cellForRowAtIndexPath

At this point the cell is created.

The height of each cell you can calculate from data model. You don't need the cell – you already know the frame width that will contain a comment, you know it's content, you know it's font, you know linebreak mode, etc. So, you can calculate height. For example:

CGFloat commentsHeight = 0;
Post *user_post = [arr_post objectAtIndex:indexPath.row];

for (NSString *comment in user_post.comments)
{
    CGRect commentrect = [comment boundingRectWithSize:CGSizeMake(self.view.bounds.size.width - 18, FLT_MAX)
                                          options:(NSStringDrawingUsesLineFragmentOrigin)
                                        attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:15]}
                                          context:nil];
    commentsHeight += commentrect.size.height;
}

And you can calculate height of the other components of cell from its data model.

But now, in 2015, it's not the best way. You really would be better to read the tutorials, which showed @Zil, and do it with Autolayout.

score 2 · Answer 2 · answered Oct 21 '15 at 04:37

You should declare an array for storing TableView cells in cellForRowAtIndexPath and you can use stored cells in heightForRowAtIndexPath. Lets Try using this.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
     static NSString *cellIdentifier = @"HomeCellID";

     HomeCell *cell = (HomeCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

     if (!cell) {
          cell = [[[HomeCell alloc] init] autorelease];
     }

     // Store table view cells in an array
     if (![tableViewCells containsObject:cell]) {
          [tableViewCells addObject:cell];
     }

     return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
     if([tableViewCellsArray objectAtIndex:indexPath.row]) {
          HomeCell *cell = (HomeCell *)[tableViewCells objectAtIndex:indexPath.row];
          // Process your Code
     }

     return yourCalculatedCellHeight;
}

score 0 · Answer 3 · edited May 23 '17 at 12:10

You could create a new cell from scratch, simply by HomeCell *sexyCell = [[HomeCell alloc]init];

or dequeue one like you did in cellForRow (tableView.dequeueWithReuseIdentifier:).

Though I advise creating one from scratch and disposing it after (setting it to nil), because if you dequeue it there they'll go in queue and cause heavy memory leaks and end up with many cells for the same indexPath.

What you COULD do is the following :

Create a cell with alloc init
Fill it with the real data
use .layoutsubviews on its view
calculate it's size and apply it to your real cell

What you SHOULD do :

Use auto layout and add all the constraints that are necessary, all your labels will size dynamically. It takes about 3 or 4 hours to get the basics of Auto layout, and about a month of regular use to really get the hang of it with ease.

I strongly strongly strongly suggest you do NOT resize using the frame of objects, most labels and views will resize like they should without having to write any code if you use constraints properly.

Once you have done that, because you have cells of varying heights, is using the DynamicHeight property of the tableview and the slight adjustements that comes with it. You can find

A great tutorial here

The same updated tutorial for swift (more up to date but you'd need to translate)

This amazing StackOverflow answer which you MUST read

I have tried this but this gives me wrong results.Like same 4th cell's image is displayed on first cel . — TechChain, Oct 20 '15 at 08:02
The only reason you would want to create a cell in heightForRow is to do some calculations for the height, for example animations. If you're getting the wrong data its because of your cellForRow:. Unless you used dequeue in heightFoRow, wich causes problems. — Gil Sand, Oct 20 '15 at 08:04
Actually just post your two methods (cellforrow and heightforrow) so I can see the complete code — Gil Sand, Oct 20 '15 at 08:04
See my edited answer. This will take you some time, but I really really strongly advise you spend a couple of days on this. It is the right path and is a good practice. — Gil Sand, Oct 20 '15 at 09:28

score 0 · Answer 4 · answered Oct 20 '15 at 08:26

I would recommend you to take the height form a configuration collection on your viewController.

Something like this:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

    CGFloat height;
    CellConfiguration * selectedCellConfiguration =[_cellConfigurations objectAtIndex:indexPath.row];

    switch (selectedCellConfiguration.type) {
        case TheTypeYouNeed:
          return TheValueYouNeed
        default:
            height = 44.0f;
            break;
    }

    return height;
}

score -3 · Answer 5 · answered Oct 20 '15 at 09:08

-3

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:indexpath.row inSection:0];

Custom Cell *cell = [tableview cellForRowAtIndexPath:indexPath];

By this , you will get each cell in your method

answered Oct 20 '15 at 09:08

Vatsal Raval

311
1
9

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This will make infinite loop – TechChain Oct 20 '15 at 09:14
By that you will be able to get each cell , then you must return a cell Height . And your app will not crash after returning it. – Vatsal Raval Oct 20 '15 at 09:19
Did you used HomeCell *cell = (HomeCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier]; , this above line , If yes ,then remove it . Because you should not reuse your cel in heightForRowAtIndexPath – Vatsal Raval Oct 20 '15 at 09:30
Also note that , heightForRowAtIndexPath method , will call before cellForRowAtIndexPath method – Vatsal Raval Oct 20 '15 at 09:40

How to get cell in heightForRowAtIndexPath?

5 Answers5