TableView insanity... please help!!

FROM : John Draper
DATE : Tue Dec 28 23:13:11 2004

Hi,

I have a number of issues involving a 3 column table view.  Each row
in the table comes from a NSDictionary as a "data source".  This almost
always has less then 100 key/value pairs,  and is created on a timely basis
(every 30 secs or so),  so it don't really matter if it's Mutable or not.

When using a dictionary as a "data source" for a Table View,  I'm using
the required callbacks...

- (int)numberOfRowsInTableView:(NSTableView *)aTableView
{
//    if (myUserDict == nil)
//        return 0;
    return([myUserDict count]);
}

- (id)tableView:(NSTableView *)aTableView
      objectValueForTableColumn:(NSTableColumn *)aTableColumn
                            row:(int)rowIndex
{
    // and I do my code here for each of the 3 columns of the
    // table view.
}

Obviously,  the "rowIndex",  going from (0....count-1) makes it a bit
difficult to reference a row when a dictionary is always referenced
by a key.  The order of the information I want displayed in the table
view is not important...  so I took a really simple approach to
also keep and maintain an array of keys.

Luckily the NSDictonary has a nice handy method "allKeys" which
generates an array of keys,  so I can now reference the keys by index.
So,  everytime I create a dictionary,  I also create this array of keys
like so...

    myIDKeys = [myUserDict allKeys];
 
Where my "Controller" maintains and manages "myUserDict", and "myIDKeys"
references as instance variables defined as follows.

    NSMutableDictionary    *myUserDict;
    NSArray                *myIDKeys;
 
In my "objectValueForTableColumn" notification callback,  I extract for
each row,  and column the key like this..

    userIDKey = [myIDKeys objectAtIndex:rowIndex];
 
which gives me the Key into a dictionary of "User" objects, of which
I reference it by...

    userObj = [myUserDict valueForKey:userIDKey];
 
With this 'userObj',  depending on the column,  I can then return a
NSString value from this 'userObj' for display in the table view.
Which it does quite nicely.  No complaints there.

Next,  logically, I want to deal with item selection in the table view,
so I dutifully define and post a notification in my "awakeFromNib"
like so...

    [[NSNotificationCenter defaultCenter] addObserver:self
                                           
selector:@selector(tableViewSelectionDidChange:)
                                               
name:NSTableViewSelectionDidChangeNotification
                                              object:nil];

Then define a method in my "controller" like this...

- (void)tableViewSelectionDidChange: (NSNotification *) notification
{
    // without boring you with details,  I do the following..
 
    if (myUserDict == nil)
        return;                // because my Dict may not be created yet
     
    row = [usersTableView selectedRow];        // get the new selected row.
 
    selectedUser = [myUserDict objectForKey:myKey];  // Get my selected
user object
 
    // 'selectedUser' is an instance variable in my "controller".
}

THE PROBLEM - and associated questions.
---------------------------------------

I traced through ALL of the code in "objectValueForTableColumn" and my
callbacks
go to completion for this routine.  No apparent object de-allocation at
this stage.

But after that,  although the Table View is populated with the proper data,
the selection is "grey" instead of "blue" color.

But the instant I try and select the table view,  I get a SIG 11 alert. 
Which
after checking it's meaning,  indicates that something has gotten
de-allocated.

I'm clueless what it is...  for instance,  when I do...

    myIDKeys = [myUserDict allKeys];
 
to make my array of keys,  I set my instance variable to point to it.
Should I do...

  myIDKeys = [[myUserDict allKeys] retain];

I've originally assumed that when this returns an array,  I can now have
control
over it and keep it for whatever.

Of course I tried the above,  with slightly different behavior.

I put a -[NSException raise] as a breakpoint,  and got this.... when I
selected
an item in the TableView.

#0    0x908311f4 in objc_msgSend
#1    0x00470724 in -[Controller
tableView:objectValueForTableColumn:row:] at Controller.m:1116
#2    0x92e7de1c in -[NSTableView mouseDown:]
#3    0x92e02c60 in -[NSWindow sendEvent:]
#4    0x92df5324 in -[NSApplication sendEvent:]
#5    0x92dfd73c in -[NSApplication run]
#6    0x92eb9b80 in NSApplicationMain
#7    0x000d9f74 in main at main.m:13


0x908311e0  <+0000>  cmplwi    r3,0
0x908311e4  <+0004>  beq-    0x90831308 <objc_msgSend+296>
0x908311e8  <+0008>  lwz    r12,0(r3)
0x908311ec  <+0012>  lwz    r12,32(r12)
0x908311f0  <+0016>  stw    r9,48(r1)
0x908311f4  <+0020>  lwz    r11,0(r12)  <---- it stops here.
0x908311f8  <+0024>  addi    r9,r12,8
0x908311fc  <+0028>  rlwinm    r11,r11,2,0,29

It appears that something (God knows what) is being de-allocated before
being used.  I have NO IDEA what it is.... nor do I have any plan or means
to find out,  since it calls some internal Apple code,  which of course
I have
NO source code for.

Then I tried it again,  this time retaining the array if keys like so...

    myIDKeys = [[myUserDict allKeys] retain];
 
I started the program again,  TableView populates properly,  but when I
click
in the tableview,  the program hangs up,  and even the debugger looses
control
and I have to force quit....  When I do,  I get this...

#0    0x9083120c in objc_msgSend
#1    0x92e7de30 in -[NSTableView mouseDown:]
#2    0x92e02c60 in -[NSWindow sendEvent:]
#3    0x92df5324 in -[NSApplication sendEvent:]
#4    0x92dfd73c in -[NSApplication run]
#5    0x92eb9b80 in NSApplicationMain
#6    0x000d9f74 in main at main.m:13

And it breaks here...

0x908311e0  <+0000>  cmplwi    r3,0
0x908311e4  <+0004>  beq-    0x90831308 <objc_msgSend+296>
0x908311e8  <+0008>  lwz    r12,0(r3)
0x908311ec  <+0012>  lwz    r12,32(r12)
0x908311f0  <+0016>  stw    r9,48(r1)
0x908311f4  <+0020>  lwz    r11,0(r12)
0x908311f8  <+0024>  addi    r9,r12,8
0x908311fc  <+0028>  rlwinm    r11,r11,2,0,29
0x90831200  <+0032>  and    r12,r4,r11
0x90831204  <+0036>  lwzx    r2,r9,r12
0x90831208  <+0040>  addi    r12,r12,4
0x9083120c  <+0044>  cmplwi    r2,0          <---- BREAKS HERE.
0x90831210  <+0048>  beq-    0x90831234 <objc_msgSend+84>
0x90831214  <+0052>  lwz    r0,0(r2)

So this DOES make SOME difference.

I hope I included everything needed for someone to show me what I'm doing
wrong.

I'm about ready to use one of my instances of support from Apple if I cannot
get any resolution from the list.    I've already been working on this
problem
for 3 weeks,  but I set it aside and did something else,  but now I'm
ready to
re-address this problem again.

Has anyone had experience with Apple's Support system?  What is the turn
around from the time I submit this and the time I get back any reply.

I COULD get approval to send my project to Apple,  but I'm sure I would
get killed if I sent the project to anyone on the Cocoadev list.

Does ANYONE know what's going on?

John