views:

50

answers:

2

Hey guys,

I have a UITableView which sometimes just stops responding when its been loaded. I have no clue why this happens and I was wondering whether it could be the layouting of the cells which I do in cellForRowAtIndexPath, because my content is dynamic and therefore the layout of the subviews has to be adopted each time.

Is there a better approach to achieche what I want? Or is there anything else wrong with this?

Here is the code I wrote:

First the method which creates the custom cell and adds the different views to the content view:

- (UITableViewCell *)tableViewCellWithReuseIdentifier:(NSString *)identifier {


    UITableViewCell *cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier] autorelease];


    UILabel *titleLbl, *amountLbl, *title2Lbl, *numberLbl, *mergeLbl, *typeLbl;


    UIColor *bgColor, *blackColor, *amountColor , *title2Color;
    UIColor *clearColor = [UIColor clearColor];


    bgColor = [UIColor clearColor];
    title2Color = [UIColor colorWithRed:0.1 green:0.1 blue:0.6 alpha:1];
    amountColor = [UIColor redColor];
    blackColor = [UIColor blackColor];

    //The number
    numberLbl = [[UILabel alloc] initWithFrame:CGRectZero];
    numberLbl.tag = kNumberLblTag;
    numberLbl.font = [UIFont systemFontOfSize:12];
    numberLbl.textAlignment = UITextAlignmentLeft;
    numberLbl.textColor = blackColor;
    numberLbl.backgroundColor = clearColor;
    numberLbl.numberOfLines = 0;
    [cell.contentView addSubview:numberLbl];
    [numberLbl release];

    amountLbl = [[UILabel alloc] initWithFrame:CGRectZero];
    amountLbl.tag = kamountLblTag;
    amountLbl.font = [UIFont systemFontOfSize:12];
    amountLbl.textAlignment = UITextAlignmentLeft;
    amountLbl.textColor = amountColor;
    amountLbl.backgroundColor = clearColor;
    amountLbl.numberOfLines = 0;
    [cell.contentView addSubview:amountLbl];
    [amountLbl release];


    mergeLbl = [[UILabel alloc] initWithFrame:CGRectZero] ;
    mergeLbl.tag = kMergeLblTag;
    mergeLbl.font = [UIFont systemFontOfSize:12];
    mergeLbl.textAlignment = UITextAlignmentLeft;
    mergeLbl.textColor = blackColor;
    mergeLbl.backgroundColor = clearColor;
    mergeLbl.numberOfLines = 0;
    [cell.contentView addSubview:mergeLbl];
    [mergeLbl release];


    typeLbl = [[UILabel alloc] initWithFrame:CGRectZero];
    typeLbl.tag = kTypeLblTag;
    typeLbl.font = [UIFont systemFontOfSize:12];
    typeLbl.textAlignment = UITextAlignmentLeft;
    typeLbl.textColor = blackColor;
    typeLbl.backgroundColor = clearColor;
    typeLbl.numberOfLines = 1;
    [cell.contentView addSubview:typeLbl];
    [typeLbl release];


    titleLbl = [[UILabel alloc] initWithFrame:CGRectZero];
    titleLbl.tag = kTitleLblTag;
    titleLbl.font = [UIFont systemFontOfSize:14];
    titleLbl.textAlignment = UITextAlignmentLeft;
    titleLbl.textColor = blackColor;
    titleLbl.backgroundColor = clearColor;
    titleLbl.numberOfLines = 0;
    [cell.contentView addSubview:titleLbl];
    [titleLbl release];


    title2Lbl = [[UILabel alloc] initWithFrame:CGRectZero];
    title2Lbl.tag = ktitle2LblTag;
    title2Lbl.font = [UIFont systemFontOfSize:12];
    title2Lbl.textAlignment = UITextAlignmentLeft;
    title2Lbl.textColor = title2Color;
    title2Lbl.backgroundColor = clearColor;    
    title2Lbl.numberOfLines = 0;
    [cell.contentView addSubview:title2Lbl];
    [title2Lbl release];


    UIView *bgView = [[UIView alloc]initWithFrame:CGRectZero];
    bgView.backgroundColor = bgColor;
    cell.backgroundView = bgView;
    [bgView release];


    NSLog(@"tableViewCellWithReuseIdentifier");

    return cell;

}

And here the method which resizes the subviews for each cell:

    // Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {



    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier];



    NSUInteger row = [indexPath row];
    NSUInteger section = [indexPath section];

    NSUInteger r = row+(section*100);

    if (cell == nil) {

        cell = [self tableViewCellWithReuseIdentifier: CellIdentifier];

    }

    UIColor *bgColor, *clearColor = [UIColor clearColor];





    //set the rePointer to the actual array 
    if (r < [results count]) {
        rePointer = results;
        //NSLog(@"results r: %i", r);
    }else {
        r = [indexPath row];
        rePointer = rejects;
        //NSLog(@"rejects r: %i", r);

    }



    NSString *noTxt = [[NSString alloc]initWithFormat:@"%i.", r+1];
    CGSize boundingSize = CGSizeMake(35, 100);
    UIFont *sysFont = [UIFont systemFontOfSize:12]; 
    CGSize requiredSize = [noTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
    CGFloat requiredHeight = requiredSize.height;

    UILabel *numberLbl = (UILabel*)[cell viewWithTag:kNumberLblTag];
    numberLbl.frame = CGRectMake(5, 5, 35, requiredHeight);
    numberLbl.text = noTxt;





    NSMutableString *amountTxt = [[NSMutableString alloc]initWithString:@"amount: "];
    [amountTxt appendString:[NSString stringWithFormat:@"%@", [[rePointer objectAtIndex:r] objectForKey:@"amount"]]];


    boundingSize = CGSizeMake(35, 100);
    sysFont = [UIFont systemFontOfSize:12]; 
    requiredSize = [amountTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
    requiredHeight = requiredSize.height;

    UILabel *amountLbl = (UILabel*)[cell viewWithTag:kamountLblTag];
    amountLbl.frame = CGRectMake(5, 20, 35, requiredHeight);
    amountLbl.text = amountTxt;





    if ([[[rePointer objectAtIndex:r] objectForKey:@"count"] intValue] > 0) {

        NSString *mergedTxt = [[NSString alloc]initWithString:@"Count"];
        boundingSize = CGSizeMake(35, 100);
        sysFont = [UIFont systemFontOfSize:12]; 
        requiredSize = [mergedTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
        requiredHeight = requiredSize.height;


        UILabel *mergeLbl = (UILabel*)[cell viewWithTag:kMergeLblTag];
        mergeLbl.frame = CGRectMake(5, 50, 35, requiredHeight);
        mergeLbl.text = mergedTxt;
        [mergedTxt release];

    }else {

        UILabel *mergeLbl = (UILabel*)[cell viewWithTag:kMergeLblTag];
        mergeLbl.frame = CGRectZero;
        mergeLbl.text = @"";

    }



    NSString *type;

    if (![[[rePointer objectAtIndex:r] objectForKey:@"type"] isEqualToString:@"NotSet"]) {
        if ([[[rePointer objectAtIndex:r] objectForKey:@"type"] isEqualToString:@"[XYZ]"]) {
            type = @"X";
        }else{
            int typeLength = [[[rePointer objectAtIndex:r] objectForKey:@"type"] length];
            type = [[[rePointer objectAtIndex:r] objectForKey:@"type"] substringWithRange:NSMakeRange(1, typeLength-2)];
        }


        UILabel *typeLbl = (UILabel*)[cell viewWithTag:kTypeLblTag];
        typeLbl.frame = CGRectMake(5, 65, 35, 20);
        typeLbl.text = type;

    }else {
        UILabel *typeLbl = (UILabel*)[cell viewWithTag:kTypeLblTag];
        typeLbl.frame = CGRectZero;
        typeLbl.text = @"";
    }






    NSString *titleTxt = [[NSString alloc]initWithString:[[[rePointer objectAtIndex:r] objectForKey:@"h_title"]stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]];


    boundingSize = CGSizeMake(190, 1000);
    sysFont = [UIFont systemFontOfSize:14];

    requiredSize = [titleTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
    requiredHeight = requiredSize.height;

    CGFloat titleHeight = requiredHeight;

    UILabel *titleLbl = (UILabel*)[cell viewWithTag:kTitleLblTag];
    titleLbl.frame = CGRectMake(50, 5, 190, requiredHeight);
    titleLbl.text = titleTxt;
    [titleTxt release];





    NSString *title2Txt = [[NSString alloc]initWithString:[[[rePointer objectAtIndex:r] objectForKey:@"title2"]stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]];

    sysFont = [UIFont systemFontOfSize:12];
    requiredSize = [title2Txt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
    requiredHeight = requiredSize.height;

    UILabel *title2Lbl = (UILabel*)[cell viewWithTag:ktitle2LblTag];
    title2Lbl.frame = CGRectMake(50, titleHeight + 10, 190, requiredHeight);
    title2Lbl.text = title2Txt;
    [title2Txt release];




    /*
    CGFloat height = [[[rePointer objectAtIndex:r] objectForKey:@"h_title"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
    height += [[[rePointer objectAtIndex:r] objectForKey:@"title2"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
    height += 20;
    */

    cell.contentView.backgroundColor = clearColor;
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

    NSLog(@"cellForRowAtIndexPath");




    /*
    cell.backgroundView.frame = CGRectMake(0, 0, 320, height-1);
    cell.backgroundView.backgroundColor = bgColor;
    */



    return cell;

}

And finally the heightForRowAtIndexPath:

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


    NSUInteger row = [indexPath row];
    NSUInteger section = [indexPath section];
    row += section*100;

    NSUInteger rejectsIndex = [indexPath row];

    if (row < [results count]) {
        CGFloat height = [[[results objectAtIndex:row] objectForKey:@"h_title"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
        height += [[[results objectAtIndex:row] objectForKey:@"title2"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
        height += 20;
        return MAX(90, height);
    }else {
        CGFloat height = [[[rejects objectAtIndex:rejectsIndex] objectForKey:@"h_title"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
        height += [[[rejects objectAtIndex:rejectsIndex] objectForKey:@"title2"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
        height += 20;

        return MAX (90, height);
    }


}

Thanks a lot for any advice!

A: 

I think your code is overly complicated and thus inefficient. Maybe you should consider using a custom table view cell which lets you access all the elements clean and directly.

I also suggest to cache the size measurements which are potentially slow.

Eiko
Well I thought about subclassing UITableViewCell. But I still would have to do the layouting of the cell each time. So why would that be much better? What exactly do you mean by caching the size measurements?
jagse
I just tried to subclass the UITableViewCell as you recommended. But still, my app just does not respond sometimes after the tableview was displayed. Mostly when I go back and forth in the navigation stack hirarchy.
jagse
You calculate the required heights and set the locations of the elements over and over again - but if this really is the problem is not clear. You might need to do some performance logging with instruments (do some scrolling and look where most cycles are spent).
Eiko
Well, first of all I have to calcualte the sizes over and over again. Might not make any sence in this example because I place the labels at fix positions. But in my "real code" this is dynamic, thus the positions of the label and therefore the frames has to be recalculated and reset each time. But that does not seem to be the problem. The scrolling performs allright. According to Instruments it does not take up a lot of memory eihter. The problem is really weird. After going back to a rootViewController and forth again quickly, the UITableViewController displays but does not respond anymore.
jagse
A: 

Because you use tag to identify the subview in the cell. Be care of one thing, DON'T use 0 for tag number, or some tag number as the same as the cell's tag value.

The method viewWithTag: will return the first subView with the tag number, if the cell's tag is the same as the one you desired, it will return cell, not a subview.

Eiko's suggestion is right, you should consider using a custom table view cell.

Toro
I did not use 0 for any tag.
jagse