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Justin W. Williams · Jul 2, 2002, 12:01 AM

Greetings,

I am working on an application with an NSTableView that will display 5 columns of data. I have set up my dataSource, but this one function keeps crashing the program on launch, and I am clueless as to why. It gives me the error that it is looking up an unknown key: (null)

<blockquote>code:<hr /><pre style="font-size:x-small; font-family: monospace;">- (id)tableView

NSTableView *)tableView
objectValueForTableColumn: (NSTableColumn *)tableColumn
row: (int)row
{
NSString *identifier = [tableColumn identifier];
Exercise *exercise = [exercises objectAtIndex: row];

return [exercise valueForKey:identifier];
}
</pre><hr /></blockquote>If anyone could assist me with this, I'd be appreciative.

smeger · Jul 2, 2002, 12:23 AM

I'd guess that excercise doesn't have a key for the identifier. Set a breakpoint in the function and debug your app. When it breaks, use the Console tab of the debugger and type
<blockquote>code:<hr /><pre style="font-size:x-small; font-family: monospace;">po identifier
po excercise</pre><hr /></blockquote>This will show you what identifier you're trying to look up and what keys are defined.

Justin W. Williams · Jul 2, 2002, 04:43 PM

identifier responded to po w/ <nil>
exercise responded with <Exercise: 0x1220760>

Why is my identifier not getting a value?

Brad Brack · Jul 2, 2002, 05:14 PM

<blockquote>quote:<hr />Originally posted by Justin W. Williams:
identifier responded to po w/ <nil>
exercise responded with <Exercise: 0x1220760>

Why is my identifier not getting a value?<hr /></blockquote>Assuming the table column is made with Interface Builder:

Have you set the identifer within Interface Builder? (That would be a different field than the column title...)

If you created the table column manually, you'd want to [yourTableColumn setIdentifier:@"column5"];

or something like that...

Justin W. Williams · Jul 2, 2002, 05:22 PM

<blockquote>quote:<hr />Originally posted by Brad Brack:
 <blockquote>quote:<hr />Originally posted by Justin W. Williams:
identifier responded to po w/ <nil>
exercise responded with <Exercise: 0x1220760>

Why is my identifier not getting a value?<hr /></blockquote>Assuming the table column is made with Interface Builder:

Have you set the identifer within Interface Builder? (That would be a different field than the column title...)

If you created the table column manually, you'd want to [yourTableColumn setIdentifier:@"column5"];

or something like that...<hr /></blockquote>I set my Data Source to point to the NSTableView in my Window. Is this what you are talking about. If not, my answer to your question would most likely be no. What do I do?

Brad Brack · Jul 2, 2002, 07:28 PM

<blockquote>quote:<hr />
I set my Data Source to point to the NSTableView in my Window. Is this what you are talking about. If not, my answer to your question would most likely be no. What do I do?<hr /></blockquote>i) In Interface Builder, double click on your NSTableView, then click once on the table column's header cell - the header should now turn blue.
ii) Do a 'Show Info' (Menu: Tools:Show Info or Command-Shift-I)

You should now see a the show info pane with NSTableColumn specific fields, e.g. Column Title and Identifier (among others)
The title corresponds to what is displayed in the column header (which you can also enter by double clicking the table column header cell)

The Identifier corresponds to what you will get from tableView: objectValueForTableColumn: row:
when you call
[tableColumn identifier];

iii) Type in your identifier that your Exercise variable will accept

note 1: you may have to hit return or tab after filling out the identifier- sometimes Interface Builder does not keep what you typed in

note 2: you may want to encapsulate your objectValueForTableColumn code in case you have muliple NSTableViews using this as a datasource
e.g.
<blockquote>code:<hr /><pre style="font-size:x-small; font-family: monospace;">- (id)tableView

NSTableView *)tableView
objectValueForTableColumn: (NSTableColumn *)tableColumn
row: (int)row
{
NSString *identifier = [tableColumn identifier];
if (tableView == myExerciseTableView) {
Exercise *exercise = [exercises objectAtIndex: row];
return [exercise valueForKey:identifier];
}
else return @"Unknown table view";
}</pre><hr /></blockquote>

Justin W. Williams · Jul 3, 2002, 12:25 AM

<blockquote>quote:<hr />Originally posted by Brad Brack:
[QUOTE]
[qb]
note 2: you may want to encapsulate your objectValueForTableColumn code in case you have muliple NSTableViews using this as a datasource
e.g.
<blockquote>code:<hr /><pre style="font-size:x-small; font-family: monospace;">- (id)tableView

NSTableView *)tableView
objectValueForTableColumn: (NSTableColumn *)tableColumn
row: (int)row
{
NSString *identifier = [tableColumn identifier];
if (tableView == myExerciseTableView) {
Exercise *exercise = [exercises objectAtIndex: row];
return [exercise valueForKey:identifier];
}
else return @"Unknown table view";
}</pre><hr /></blockquote><hr /></blockquote>Keeps telling me that myExerciseTableView is undeclared. I am assuming this is pointing to my IBOutlet id myExerciseTableView I have setup in my Controller class. Am I right?

Brad Brack · Jul 3, 2002, 02:59 AM

Originally posted by Justin W. Williams:
<blockquote>quote:<hr />Keeps telling me that myExerciseTableView is undeclared. I am assuming this is pointing to my IBOutlet id myExerciseTableView I have setup in my Controller class. Am I right?<hr /></blockquote>yes- the myExerciseTableView is your IBOutlet- sorry for not making that clear. Also, you'll have to do the connection in Interface Builder. Is your data source not the controller? If it isn't, then you won't be able to access that IBOutlet directly (and thus you may not want to encapsulate as I suggested, or else you'll have to do some more connections...)

Justin W. Williams · Jul 3, 2002, 04:47 PM

<blockquote>quote:<hr />Originally posted by Brad Brack:
Originally posted by Justin W. Williams:
<blockquote>quote:<hr />Keeps telling me that myExerciseTableView is undeclared. I am assuming this is pointing to my IBOutlet id myExerciseTableView I have setup in my Controller class. Am I right?<hr /></blockquote>yes- the myExerciseTableView is your IBOutlet- sorry for not making that clear. Also, you'll have to do the connection in Interface Builder. Is your data source not the controller? If it isn't, then you won't be able to access that IBOutlet directly (and thus you may not want to encapsulate as I suggested, or else you'll have to do some more connections...)<hr /></blockquote>I have a Controller class that has all my IBOutlet declarations + methods to calculate some values & open/close sheets.

My DataSource class has all my tableView stuff.

Should I consolidate all this stuff into one?