MapKit exception: Cannot remove an observer for the key path "title" - ios

Question

I'm getting quite a lot of crashes like this.
In my code, I'm not doing any KVO on my MKAnnotation objects that could explain this exception. So to me, it looks like an iOS bug.
Did anybody else experience similar crashes?
*** Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer for the key path "title" from because it is not registered as an observer.'
Thread 0 Crashed:
0 libSystem.B.dylib 0x000792d4 __kill + 8
1 libSystem.B.dylib 0x000792bd raise + 17
2 WhereTo 0x000a430d uncaught_exception_handler (PLCrashReporter.m:137)
3 CoreFoundation 0x000a0adf __handleUncaughtException + 239
4 libobjc.A.dylib 0x00006593 _objc_terminate + 103
5 libstdc++.6.dylib 0x00042df9 __cxxabiv1::__terminate(void (*)()) + 53
6 libstdc++.6.dylib 0x00042e4d std::terminate() + 17
7 libstdc++.6.dylib 0x00042f1d __cxa_throw + 85
8 libobjc.A.dylib 0x000054cb objc_exception_throw + 71
9 CoreFoundation 0x000a07c9 +[NSException raise:format:arguments:] + 69
10 CoreFoundation 0x000a0803 +[NSException raise:format:] + 35
11 Foundation 0x00031b4d -[NSObject(NSKeyValueObserverRegistration) _removeObserver:forProperty:] + 545
12 Foundation 0x000318a1 -[NSObject(NSKeyValueObserverRegistration) removeObserver:forKeyPath:] + 121
13 MapKit 0x00024e75 -[MKAnnotationContainerView _unregisterObserverForBubbleAnnotation:] + 133
14 MapKit 0x0001fd29 -[MKAnnotationContainerView setBubbleAnnotationView:] + 73
15 MapKit 0x0001f4e3 -[MKAnnotationContainerView _showBubbleForAnnotationView:bounce:scrollToFit:userInitiated:avoid:] + 211
16 MapKit 0x0001f235 -[MKAnnotationContainerView _setSelectedAnnotationView:bounce:pressed:scrollToFit:userInitiated:avoid:] + 357
17 MapKit 0x0001f0bf -[MKAnnotationContainerView _setSelectedAnnotationView:bounce:pressed:scrollToFit:userInitiated:] + 83
18 MapKit 0x000248ab -[MKMapView handleTap:] + 195
19 CoreFoundation 0x0003ebbf -[NSObject(NSObject) performSelector:withObject:] + 23
20 UIKit 0x0009a3d3 -[UIGestureRecognizer _updateGestureWithEvent:] + 575
21 UIKit 0x0009a18b -[UIGestureRecognizer _delayedUpdateGesture] + 23
22 UIKit 0x000017b1 _UIGestureRecognizerUpdateObserver + 437
23 CoreFoundation 0x00030c59 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 17
24 CoreFoundation 0x00030acd __CFRunLoopDoObservers + 413
25 CoreFoundation 0x000280cb __CFRunLoopRun + 855
26 CoreFoundation 0x00027c87 CFRunLoopRunSpecific + 231
27 CoreFoundation 0x00027b8f CFRunLoopRunInMode + 59
28 GraphicsServices 0x000044ab GSEventRunModal + 115
29 GraphicsServices 0x00004557 GSEventRun + 63
30 UIKit 0x00037329 -[UIApplication _run] + 413
31 UIKit 0x00034e93 UIApplicationMain + 671
32 WhereTo 0x00003475 main (main.m:14)

Answer 1

I had a similar crash with MapKit starting in OS 4.x.
By 'similar' I mean it was related to KVO and observers but I don't remember the details.
The problem was:
I had a class implenting the MKAnnotation protocol.
But in this class I was accessing the coordinate property without using KVO (directly via the corresponding ivar):
_coordinate = ....
instead of
self.coordinate = ...
It seems that Mapkit is now (starting in OS 4) relying on KVO notification to monitor annotations position.

Answer 2

Turns out, I wrote to the property from background threads which is a no-go. If I make sure to only set it from the main thread, the problem seems to go away.

Answer 3

For future reference; I got the exact same error, but in my case it was caused by trying to programmatically select an annotation that hadn't yet been added to the mapview.

Answer 4

I had a similar issue, but the property getter was a defined function but there was no setter. The MKAnnotation protocol requires a property (getter and setter).

Answer 5

I use same in two MKMapView's and exception thrown when call removeAnnotations: from second map, this try-catch fix problem.
#implementation MyAnnotation //<MKAnnotation>
- (void)removeObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath
{
#try
{
[super removeObserver:observer forKeyPath:keyPath];
}
#catch(...)
{
}
}
#end