iphone sdk delegate failed to return after waiting 10 seconds in table view loading huge data from database

Question

SendDelegateMessage: delegate failed to return after waiting 10 seconds. main run loop mode: kCFRunLoopDefaultMode If you were not using the touch screen for this entire interval (which can prolong this wait), please file a bug.

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath  { 
    /*
    //NSString *label = [self.aNote length] == 0 ? kDefaultNoteLabel : self.aNote;
    NSString *label = [countriesToLiveInArray objectAtIndex:indexPath.row];

    //CGFloat height = [label RAD_textHeightForSystemFontOfSize:kTextViewFontSize] + 20.0;
    //return height;
    float lineHeight = [ @"Fake line" sizeWithFont: [UIFont fontWithName:@"MarkerFelt-Thin" size:15] ].height;


    int numLines = [label sizeWithFont: [UIFont fontWithName:@"MarkerFelt-Thin" size:15]  constrainedToSize: CGSizeMake(250, lineHeight*1000.0f) lineBreakMode: UILineBreakModeTailTruncation ].height / lineHeight;
    CGSize labelsize =  CGSizeMake(250, (lineHeight*(float)numLines));
    return labelsize.height+10;
     */
    return 100;

}

this delegate is the prob.if i comment out this whole function then program works. ad table view use default height but is we return any kind of return value then it shows the message...please help us.

Answer 1

Using -heightForRowAtIndexPath: is very expensive for tables with a large number of rows. It has to be called once for every row in the table, not just the visible rows. Apple warns about it in the documentation:

There are performance implications to using tableView:heightForRowAtIndexPath: instead of the rowHeight property. Every time a table view is displayed, it calls tableView:heightForRowAtIndexPath: on the delegate for each of its rows, which can result in a significant performance problem with table views having a large number of rows (approximately 1000 or more).

Unless you can cache some information to make the method run more quickly, you should probably consider using a fixed row height.