-[_NSObserverList setCursorPosition:]

Question

I am getting #560 NSInvalidArgumentException error as shown below;

-[_NSObserverList setCursorPosition:]: unrecognized selector sent to instance 0x1702a6ea0

CoreFoundation ___exceptionPreprocess

Fatal Exception: NSInvalidArgumentException
0  CoreFoundation                 0x1854f21c0 __exceptionPreprocess
1  libobjc.A.dylib                0x183f2c55c objc_exception_throw
2  CoreFoundation                 0x1854f9278 __methodDescriptionForSelector
3  CoreFoundation                 0x1854f6278 ___forwarding___
4  CoreFoundation                 0x1853f059c _CF_forwarding_prep_0
5  UIKit                          0x18b830418 -[_UIKeyboardTextSelectionController selectTextWithGranularity:atPoint:executionContext:]
6  UIKit                          0x18b8304b0 -[_UIKeyboardTextSelectionController selectTextWithGranularity:atPoint:completionHandler:]
7  UIKit                          0x18b895928 -[_UIKeyboardBasedNonEditableTextSelectionGestureController oneFingerForcePan:]
8  UIKit                          0x18b91b59c -[UIGestureRecognizerTarget _sendActionWithGestureRecognizer:]
9  UIKit                          0x18b91eca4 _UIGestureRecognizerSendTargetActions
10 UIKit                          0x18b4e02e8 _UIGestureRecognizerSendActions
11 UIKit                          0x18b37e828 -[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:]
12 UIKit                          0x18b90ece8 _UIGestureEnvironmentUpdate
13 CoreFoundation                 0x18549f7dc __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
14 CoreFoundation                 0x18549d40c __CFRunLoopDoObservers
15 CoreFoundation                 0x18549d89c __CFRunLoopRun
16 CoreFoundation                 0x1853cc048 CFRunLoopRunSpecific
17 GraphicsServices               0x186e52198 GSEventRunModal
18 UIKit                          0x18b3b82fc -[UIApplication _run]
19 UIKit                          0x18b3b3034 UIApplicationMain
20 MyAppName                      0x100050054 main (main.m:16)
21 libdispatch.dylib              0x1843b05b8 (Missing)

Can anyone please suggest me what can be the issue?

Answer 1

This kind of NSInvalidArgumentException, especially because it's on a private class, is probably due to a Zombie object. You are sending a message "setCursorPosition:" to an object that no longer exist, but another one is in it's place. In this case "_NSObserverList".

Try running with the "Zombie Objects" diagnostics objects to trace down which is the object that should receive that message but was gone. That option keeps the objects in memory when they are released, but marked as zombies.