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POAdding yourself as an observer to an array than an NSArrayController is bound to?
 

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  1. POAdding yourself as an observer to an array than an NSArrayController is bound to?
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    <p>I have class called <code>AppController</code> which contains a mutable array of <code>Person</code> objects called <code>people</code>. Each person simply has an NSString and a float. </p> <p>I also have an <code>NSArrayController</code> whose <code>contentArray</code> is bound to the <code>people</code> array in AppController. Then I have the usual setup of a table view bound to the array controller to show a list of all the person objects.</p> <p>In my AppController class, I tried to register as an observer of the people array to add undo support. Here's how I do it:</p> <pre><code>@implementation AppController @synthesize people; - (id)init { self = [super init]; if (self != nil) { people = [[NSMutableArray alloc] init]; undoManager = [[NSUndoManager alloc] init]; [self addObserver:self forKeyPath:@"people" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL]; } return self; } - (void)undo:(id)sender { [undoManager undo]; } - (void)redo:(id)sender { [undoManager redo]; } - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { int kindOfChange = [[change objectForKey:NSKeyValueChangeKindKey] intValue]; int index = [[change objectForKey:NSKeyValueChangeIndexesKey] firstIndex]; Person *p; if (kindOfChange == NSKeyValueChangeInsertion) { p = [change objectForKey:NSKeyValueChangeNewKey]; [[undoManager prepareWithInvocationTarget:self] removePersonAtIndex:index]; } else { p = [change objectForKey:NSKeyValueChangeOldKey]; [[undoManager prepareWithInvocationTarget:self] addPerson:p atIndex:index]; } } - (void)addPerson:(Person *)person atIndex:(int)index { [[self mutableArrayValueForKey:@"people"] addObject:person]; } - (void)removePersonAtIndex:(int)index { [[self mutableArrayValueForKey:@"people"] removeObjectAtIndex:index]; } @end </code></pre> <p>With this code, I can successfully add a person object and then undo it. I cannot, however, undo deleting a person object. I always get this exception when I undo a delete operation:</p> <pre><code>[&lt;NSCFArray 0x3009a0&gt; addObserver:forKeyPath:options:context:] is not supported. Key path: personName </code></pre> <p>It seems like I'm not the only one, though: <a href="http://www.cocoabuilder.com/archive/cocoa/84489-modifying-the-array-of-an-nsarraycontroller.html#84496" rel="nofollow noreferrer">http://www.cocoabuilder.com/archive/cocoa/84489-modifying-the-array-of-an-nsarraycontroller.html#84496</a></p> <p>Any ideas?</p> <p>UPDATE:</p> <p>Here's the backtrace:</p> <pre><code>#0 0x7fff8161b41e in -[NSArray(NSKeyValueObserverRegistration) addObserver:forKeyPath:options:context:] #1 0x7fff8822fc47 in -[_NSModelObservingTracker _registerOrUnregister:observerNotificationsForModelObject:] #2 0x7fff883b2bb9 in -[_NSModelObservingTracker startObservingModelObjectAtReferenceIndex:] #3 0x7fff883acc41 in -[_NSModelObservingTracker setObservingToModelObjectsRange:] #4 0x7fff883aca5a in -[NSTableBinder tableView:updateVisibleRowInformation:] #5 0x7fff883ac98e in -[_NSBindingAdaptor tableView:updateVisibleRowInformation:] #6 0x7fff882b4c7b in -[NSTableView drawRect:] #7 0x7fff882ab081 in -[NSView _drawRect:clip:] #8 0x7fff882a9cf4 in -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] #9 0x7fff882aa05e in -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] #10 0x7fff882aa05e in -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] #11 0x7fff882a83c6 in -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] #12 0x7fff882a9292 in -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] #13 0x7fff882a9292 in -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] #14 0x7fff882a7ee8 in -[NSThemeFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] #15 0x7fff882a479a in -[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:] #16 0x7fff8821dff6 in -[NSView displayIfNeeded] #17 0x7fff88218ea2 in _handleWindowNeedsDisplay #18 0x7fff81da9077 in __CFRunLoopDoObservers #19 0x7fff81d84ef4 in __CFRunLoopRun #20 0x7fff81d8484f in CFRunLoopRunSpecific #21 0x7fff8836ab31 in _NSUnhighlightCarbonMenu #22 0x7fff8834d0c1 in -[NSMenu performKeyEquivalent:] #23 0x7fff8834be69 in -[NSApplication _handleKeyEquivalent:] #24 0x7fff8821caa1 in -[NSApplication sendEvent:] #25 0x7fff881b3922 in -[NSApplication run] #26 0x7fff881ac5f8 in NSApplicationMain #27 0x100001469 in main at main.m:13 </code></pre>
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      1. POAdding yourself as an observer to an array than an NSArrayController is bound to?
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    1. COPlase post the code where you observe `personName`. Also, do `self=[super init];` rather than just `[super init]`.
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    2. COI'm not observing personName, which is why I'm kind of confused. I *think* the NSArrayController is the one that's calling -addObserver:forKeyPath:options:context: on the NSCFArray.
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    3. COI've updated the question to make it more clear. Thanks.
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