Re: NSTokenField bug in 10.5.2?

FROM : Tom Bunch
DATE : Wed Mar 12 22:55:31 2008

It looks like the answer here is that there's no great workaround. 
Linked against 10.4, NSTokenField will not preserve your whitespace.   
The delegate method:

- (id)tokenField:(NSTokenField *)tokenField 
representedObjectForEditingString:(NSString *)editingString

is not called with an editingString that contains nothing but 
whitespace.  If I'm recalling my results correctly, if editingString 
ought to be "  xx  ", the leading whitespace is trimmed but not the 
trailing.  This means that you cannot implement an interface like 
System Preferences->International->Custom Formats, link against the 
10.4 sdk, and expect it to work properly on Leopard.

The workaround I came up with is not entirely satisfactory, but I 
think it will work for users for the time being.  I wound up 
implementing another delegate method:

- (BOOL)control:(NSControl *)control isValidObject:(id)object

and replacing whitespace characters in object with something I didn't 
really expect to see (I think I chose an Ethiopic wordspace).  Then, 
in representedObjectForEditingString:, I check for that character in 
editingString.  If I get it, I just make an instance of a trivial 
token class that only exists to turn strings in to tokens.  Finally, 
if I don't return NSDefaultTokenStyle from 
tokenField:styleForRepresentedObject:, entering and exiting the token 
field will cause the space to be re-trimmed and the token to go away, 
even though no editing took place (and control:isValidObject: and 
controlTextDidChange: are not called).  So I do that.  My whitespace 
characters are thus each turned into a single space (I could probably 
encode different whitespace characters as different obscure 
characters, but I don't care quite that much) and show up in the token 
field w/ a lozenge around them.

The test app at http://people.omnigroup.com/tom/NSTokenField.zip has 
been modified w/ the workaround.

-Tom

On Mar 10, 2008, at 3:00 PM, Tom Bunch wrote:

> Hey developers,
>
> I've been grappling with a problem very similar to this month's 
> earlier thread with the same subject line.  The consensus there was 
> that in 10.4 NSTokenField always trims off whitespace before the 
> input it tokenized.  In fact, my experience is the opposite.  In 
> OmniPlan we have an interface much like the custom formats in System 
> Preferences -> International -> Formats – you can drag in tokens and 
> add text to delimit between them.  Built against the 10.4 SDK and 
> run on 10.4, this accepts spaces in the token field and passes them 
> on to me, but when the same binary is run on Leopard, the spaces are 
> just gone.  You get dates like "January2008", unless you delimit w/ 
> non-whitespace.
>
> I've cobbled together a very simple test app and put the source up 
> at http://people.omnigroup.com/tom/NSTokenField.zip.  It just 
> prepopulates an NSTextField w/ a couple of tokens and logs the 
> objectValue if you edit the field.
>
> Run this on Tiger, put some spaces in between tokens and hit tab, 
> you get a log like this:
>
> 2008-03-10 14:03:16.929 NSTokenField[239] token field objectValue  = 
> (<Token: 0x343f60>, "  ", <Token: 0x344140>)
>
> On Leopard, you get:
>
> 2008-03-10 14:03:16.929 NSTokenField[239] token field objectValue  = 
> (<Token: 0x343f60>, <Token: 0x344140>)
>
> This is pretty easy to fix if I target 10.5, but this build needs to 
> target 10.4 and hopefully still behave on 10.5.
>
> In the earlier thread, Aki Inoue confirmed that:

>> The logic to determine whether or not to apply the auto whitespace 
>> trimming is:
>> - trims if linked against 10.4.x binary

>
> That seems to be true... linked against 10.4 and run on 10.5, but 
> it's not consistent with the behavior linked against 10.4 and run on 
> 10.4, so it doesn't really solve the binary compatibility problem. 
> Any suggestions for a workaround would be appreciated!
>
> Thanks!
>
> -Tom Bunch
> Omni
>
>
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