Logout Button crash - swift

Question

I just implemented a logout button on my HeaderView sector. But somehow I keep getting this crash from Xcode.
I feel like this is somehow related to my func logoutBtnClicked(){***}.
so here is what my logoutBtnClicked() looks like:
//clicked logout
#IBAction func logout(sender: AnyObject) {
PFUser.logOutInBackgroundWithBlock { (error: NSError?) -> Void in
if error == nil {
NSUserDefaults.standardUserDefaults().removeObjectForKey("username")
NSUserDefaults.standardUserDefaults().synchronize()
let signin = self.storyboard?.instantiateViewControllerWithIdentifier("signinViewController") as! SigninViewController
let appDelegate: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.window?.rootViewController = signin
}
}
}
2016-08-18 21:18:54.801 helloworld[2439:115160] -[helloworld.HomeViewController Logout:]: unrecognized selector sent to instance 0x78e38840
2016-08-18 21:18:54.829 helloworld[2439:115160] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[helloworld.HomeViewController Logout:]: unrecognized selector sent to instance 0x78e38840'
* First throw call stack:
(
0 CoreFoundation 0x018d1494 exceptionPreprocess + 180
1 libobjc.A.dylib 0x035e5e02 objc_exception_throw + 50
2 CoreFoundation 0x018db253 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
3 CoreFoundation 0x0181089d ___forwarding_ + 1037
4 CoreFoundation 0x0181046e _CF_forwarding_prep_0 + 14
5 libobjc.A.dylib 0x035fa0b5 -[NSObject performSelector:withObject:withObject:] + 84
6 UIKit 0x020c1e38 -[UIApplication sendAction:to:from:forEvent:] + 118
7 UIKit 0x025519da -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 179
8 libobjc.A.dylib 0x035fa0b5 -[NSObject performSelector:withObject:withObject:] + 84
9 UIKit 0x020c1e38 -[UIApplication sendAction:to:from:forEvent:] + 118
10 UIKit 0x020c1db7 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 64
11 UIKit 0x02265f3b -[UIControl sendAction:to:forEvent:] + 79
12 UIKit 0x022662d4 -[UIControl _sendActionsForEvents:withEvent:] + 433
13 UIKit 0x02266483 -[UIControl _sendActionsForEvents:withEvent:] + 864
14 UIKit 0x022652c1 -[UIControl touchesEnded:withEvent:] + 714
15 UIKit 0x0214252e -[UIWindow _sendTouchesForEvent:] + 1095
16 UIKit 0x021435cc -[UIWindow sendEvent:] + 1159
17 UIKit 0x020e4be8 -[UIApplication sendEvent:] + 266
18 UIKit 0x020b9769 _UIApplicationHandleEventQueue + 7795
19 CoreFoundation 0x017e3e5f CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 15
20 CoreFoundation 0x017d9aeb __CFRunLoopDoSources0 + 523
21 CoreFoundation 0x017d8f08 __CFRunLoopRun + 1032
22 CoreFoundation 0x017d8846 CFRunLoopRunSpecific + 470
23 CoreFoundation 0x017d865b CFRunLoopRunInMode + 123
24 GraphicsServices 0x05f27664 GSEventRunModal + 192
25 GraphicsServices 0x05f274a1 GSEventRun + 104
26 UIKit 0x020bfeb9 UIApplicationMain + 160
27 helloworld 0x0007a4e1 main + 145
28 libdyld.dylib 0x043bba25 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

The problem is that in the interface builder for HomeViewController, for button action you have set Logout and inside the class of HomeViewController it is declare as logout, action and property are case sensitive, so either change one of them will solve your crash.