Question

i was implementing the table view programmatically, where i set property of mSelectedSubUnitIndex of (NSIndexPath) type as non atomic and retain and synthesized in .m . When i load my tableviewcontroller then method:

(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath
:(NSIndexPath    *)indexPath
{
CGFloat height = 0.0;
    SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:indexPath.row];
NSArray *subUnitExercises = [self sortArray:[subUnit.subUnitExercise allObjects]];
  NSLog(@"mSelectedSubUnitIndex.row........%d",mSelectedSubUnitIndex.row);
NSLog(@"subUnitExercises........%d",[subUnitExercises count]);
  if (indexPath.row == mSelectedSubUnitIndex.row && [subUnitExercises count]>1) {
    height =CELL_EXPAND_HEIGHT ;
}
else {
    height = CELL_NORMAL_HEIGHT;
}
return height;   
} 

run quite fine. When i return back to my tableviewcontoller from other controller then it crashes(object message send) at same method on line number 5 at NSLog, and give exception at method at [self.tableView reloadData];. It is resolved by commenting[self.tableView reloadData];.

-(void)viewDidAppear:(BOOL)animated

{
DebugLog(@"start");
    //[self.tableview reloadData];

execountarray=[[NSMutableArray alloc]init];
for(int k=0;k<[mSubUnitsArray count];k++)
{
    SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:k];
    NSArray *subUnitExercises = [subUnit.subUnitExercise allObjects];
    [execountarray addObject:[NSString stringWithFormat:@"%d",[subUnitExercises  
    count]]];
}

///////////////
if (managedObjectContext){

    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription 
entityForName:@"TSubUnitExerciseProgress" inManagedObjectContext:managedObjectContext];
    [request setEntity:entity];

    // Order the events by creation date, most recent first.
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] 
  initWithKey:@"editDate" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, 
    nil];
    [request setSortDescriptors:sortDescriptors];
    [sortDescriptor release];
    [sortDescriptors release];

    // Execute the fetch -- create a mutable copy of the result.
    NSError *error = nil;
    NSMutableArray *mutableFetchResults = [[managedObjectContext 
    executeFetchRequest:request error:&error] mutableCopy];
    if (mutableFetchResults == nil) {
        // Handle the error.
        myNotes = nil;
        [myNotes removeAllObjects]; 
    }
    else
    {
        [myNotes setArray: mutableFetchResults];
    }



    //NSLog(@"My notes count:--------unitviewcontroller--------------->%d", 
      [myNotes count]);
    if([myNotes count] ==0)
    {
    setExer1Done:NO;
    setExer2Done:NO;
    }
    else 
    {
        NSLog(@"hey :P");

    }

}
//  [self.tableview reloadData];  

}

didSelectRowAtIndex

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath 
*)indexPath 
{
DebugLog(@" -start- \n");
mSelectedSubUnitIndex = indexPath;
SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:indexPath.row];
NSArray *subUnitExercises = [self sortArray:[subUnit.subUnitExercise allObjects]];
if([subUnitExercises count]!=1) 
{
    NSArray* paths = [NSArray arrayWithObject:[NSIndexPath indexPathForRow:  
[mSelectedSubUnitIndex row] inSection:0]];
    [tableview beginUpdates];
    [tableview deleteRowsAtIndexPaths:paths   
withRowAnimation:UITableViewRowAnimationFade];
    [tableview insertRowsAtIndexPaths:paths  
withRowAnimation:UITableViewRowAnimationFade];
    [tableview endUpdates];
}
else
{
    //SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:  
[mSelectedSubUnitIndex row]];
    SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:indexPath.row];
    NSArray *subUnitExercises = [self sortArray:[subUnit.subUnitExercise 
 allObjects]];
    if ([subUnitExercises count] > 0) {
        SubUnitExercise *subUnitExercise = [subUnitExercises 
 objectAtIndex:0];
        [self loadSubUnitExercise:subUnitExercise];
    }
}
  }

this is running on iOS 4 but when i build through Xcode version 4.2 and iOS 5 (released oct-12, 2011) then it crashes. Can’t figure out the problem. help me out!!

cellForRowAtIndex method

now i am getting exception at if-statement at mSelectedsubunitindex.row when i scroll, but i resolved only checking that if (indexPath.row){}, and also row remain selected when i return bad to my tableview controller

- (void)tableView:(UITableView *)tableView willDisplayCell:
 (UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
 {    
DebugLog(@"-start- \n");
SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:indexPath.row];
NSArray *subUnitExercises = [self sortArray:[subUnit.subUnitExercise allObjects]];
NSString *str1 = [[subUnit performSelector:@selector(title)]copy];
if ([str1 isEqualToString:@"1. was/were"]) 
{
    global = str1;
}
//if(indexPath.row==mSelectedSubUnitIndex.row)
if(indexPath.row)
    {

    if ([subUnitExercises count] != 1)
    {
      SubUnit *subUnit = (SubUnit*)[mSubUnitsArray objectAtIndex:            
      [mSelectedSubUnitIndex row]];
        NSArray *subUnitExercises = [self sortArray:
        [subUnit.subUnitExercise allObjects]];
        SubUnitCell *subUnitcell = (SubUnitCell*) cell;

        mCellSubTopicLabel.text = subUnit.title;

        if([myNotes count] == 0)
        {
            NSNumber *isDone = [[subUnitExercises objectAtIndex:1] isDone];

            [subUnitcell setExer2Done:NO];
            mExer2Checkbox.image = [UIImage imageNamed:[isDone boolValue]?   
            kExerciseCheckmark :kExerciseWrongmark];

            isDone = [[subUnitExercises objectAtIndex:0] isDone];
            [subUnitcell setExer1Done:NO];
            mExer1Checkbox.image = [UIImage imageNamed:[isDone boolValue]?
             kExerciseCheckmark :kExerciseWrongmark];

        }
        else 
        {
            NSNumber *isDone = [[subUnitExercises objectAtIndex:1] isDone];

            [subUnitcell setExer2Done:[isDone boolValue]];
            mExer2Checkbox.image = [UIImage imageNamed:[isDone boolValue]?
            kExerciseCheckmark :kExerciseWrongmark];
            isDone = [[subUnitExercises objectAtIndex:0] isDone];
            [subUnitcell setExer1Done:[isDone boolValue]];
            mExer1Checkbox.image = [UIImage imageNamed:[isDone boolValue]?
            kExerciseCheckmark :kExerciseWrongmark];        
        }
        [subUnitcell.contentView addSubview:mCellSubTopicContentView];

}

}

Answer 1

For some reason NSIndexPath assignment (=) and equality(==) is not working in IOS5. I have solved the problem using self before any NSIndexPath object e.g.

self.mSelectedSubUnitIndex

There is another way solving this assignment using copy like this:

anIndexPath = (NSIndexPath*) [anotherIndexPath  copy];

Equality works in same way. Like:

if([self.mSelectedSubUnitIndex isEqual:anotherIndexPath])
{

}