Re: BOOL madness
Re: BOOL madness
- Subject: Re: BOOL madness
- From: Charles Steinman <email@hidden>
- Date: Tue, 11 Nov 2008 17:18:08 -0800 (PST)
That's because you're getting an object pointer back, and any object pointer except for nil evaluates to true. Assuming you know it will only be one object inserted at a time, you'd want to do [[change objectForKey:NSKeyValueChangeNewKey] boolValue].
Cheers,
Chuck
----- Original Message ----
> From: Andre Masse <email@hidden>
> To: Cocoa Developers <email@hidden>
> Sent: Tuesday, November 11, 2008 5:08:20 PM
> Subject: BOOL madness
>
> Hi,
>
> I'm having trouble converting an object to a BOOL. In my window controller, I'm
> observing the model keyPath isDirty which is a BOOL.
>
> version 1
> ----------------
> - (void) observeValueForKeyPath:(NSString *)keyPath
> ofObject:(id)object
> change:(NSDictionary *)change
> context:(void *)context
> {
> if(object == model) {
> if([keyPath isEqualToString:@"isDirty"]) {
> [self setDocumentEdited:[change
> objectForKey:NSKeyValueChangeNewKey]];
>
> }
> }
>
> }
>
> This doesn't work. No matter what the value of isDirty is, setDocumentEdited: is
> always called with YES;
>
>
> So, I add some logging, flags and everything to see what's going on:
>
> version 2
> ----------------
> - (void) observeValueForKeyPath:(NSString *)keyPath
> ofObject:(id)object
> change:(NSDictionary *)change
> context:(void *)context
> {
> if(object == model) {
> if([keyPath isEqualToString:@"isDirty"]) {
> BOOL flag = [change
> objectForKey:NSKeyValueChangeNewKey];
> NSLog(@"change value = %@", [change
> objectForKey:NSKeyValueChangeNewKey]);
> if(flag) {
> [self setDocumentEdited:YES];
> }
> else {
> [self setDocumentEdited:NO];
> }
>
> }
> }
> }
>
> Now, the logging shows that [change objectForKey:NSKeyValueChangedNewKey] toggle
> between 0 and 1 according to the value of isDirty, but flag is always YES... I
> also tried using a plain c bool and got the same result (true). Any idea what
> I'm doing wrong?
>
> Thanks,
>
> Andre Masse
>
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| References: | |
| | >BOOL madness (From: Andre Masse <email@hidden>) |