KVO - observeValueForKeyPath not called when observing an enum

Question

I've used NSNotifications before but this is the first time I've tried to use KVO in Cocoa Touch.

My UITableView controller switches between a variety of datasources so I've encapsulated them in different UITableViewDataSource subclasses. I'm trying to have my view controller observe a specific one of these UITableViewDataSource subclasses and track an enum called loadState that reflects the models the load state.

I set the observer like this:

[self.siteUpdatesDataSource addObserver:self
                             forKeyPath:@"loadState"
                                options:0
                                context:nil];

From the debugger I can see that the observer is registered:

(gdb) po [self siteUpdatesDataSource]
<SiteUpdatesTableViewDataSource: 0x651e5a0>
Current language:  auto; currently objective-c
(gdb) po [[self siteUpdatesDataSource] observationInfo]
<NSKeyValueObservationInfo 0x651dd70> (
<NSKeyValueObservance 0x651dd10: Observer: 0xc80f1e0, Key path: loadState, Options: <New: NO, Old: NO, Prior: NO> Context: 0x0, Property: 0x651dd90>

)

However, my observeValueForKeyPath method in my viewController never seems to be called. I set a breakpoint and nothing ever reaches it even when I validate that the enum has changed.

- (void) observeValueForKeyPath:(NSString *)keyPath 
                        ofObject:(id)object
                          change:(NSDictionary *)change
                         context:(void *)context {

   [self.tableView reloadData];
}

I appreciate any thoughts on what I'm missing.

Answer 1

Can't see any problem. Are you sure you change loadState property by calling synthesized accessor or by using KVC or manually (notifying about changes with willChangeValueForKey: and didChangeValueForKey:)?