Q:

Thread 1:signal SIGABRT error

i am getting a sigabrt error in my code and i am not able to resolve it. I have tried several options but all is going in vain. 
The code where am getting the error is 
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject : AnyObject]?) -> Bool {

    UINavigationBar.appearance().tintColor = UIColor.whiteColor()
    UINavigationBar.appearance().barTintColor = UIColor(red: 0.66, green: 0.78, blue: 0.31, alpha: 1)
    UIButton.appearance().tintColor = UIColor(red: 0.88, green: 0.53, blue: 0.21, alpha: 1)

    return true

The console is showing this error 
*2016-08-23 20:37:24.081 to-do list[35600:1421134] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Pushing a navigation controller is not supported'
*** First throw call stack:
(
    0   CoreFoundation                      0x0068aa94 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x02424e02 objc_exception_throw + 50
    2   UIKit                               0x01214a0e __71-[UINavigationController pushViewController:transition:forceImmediate:]_block_invoke + 0
    3   UIKit                               0x01213e27 __54-[UINavigationController pushViewController:animated:]_block_invoke + 351
    4   UIKit                               0x01213c83 -[UINavigationController pushViewController:animated:] + 786
    5   UIKit                               0x01213f0e __54-[UINavigationController pushViewController:animated:]_block_invoke1548 + 52
    6   UIKit                               0x01aed0ce -[_UIViewControllerTransitionCoordinator _applyBlocks:releaseBlocks:] + 292
    7   UIKit                               0x01ae8d82 -[_UIViewControllerTransitionContext _runAlongsideCompletions] + 147
    8   UIKit                               0x01ae8a6d -[_UIViewControllerTransitionContext completeTransition:] + 136
    9   UIKit                               0x00fe963e __53-[_UINavigationParallaxTransition animateTransition:]_block_invoke93 + 879
    10  UIKit                               0x010bdc64 -[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:] + 647
    11  UIKit                               0x010983c7 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 247
    12  UIKit                               0x010987bd -[UIViewAnimationState animationDidStop:finished:] + 90
    13  QuartzCore                          0x04baee97 _ZN2CA5Layer23run_animation_callbacksEPv + 305
    14  libdispatch.dylib                   0x02e789cd _dispatch_client_callout + 14
    15  libdispatch.dylib                   0x02e5e018 _dispatch_main_queue_callback_4CF + 910
    16  CoreFoundation                      0x005dc70e __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
    17  CoreFoundation                      0x0059a454 __CFRunLoopRun + 2356
    18  CoreFoundation                      0x00599866 CFRunLoopRunSpecific + 470
    19  CoreFoundation                      0x0059967b CFRunLoopRunInMode + 123
    20  GraphicsServices                    0x054a8664 GSEventRunModal + 192
    21  GraphicsServices                    0x054a84a1 GSEventRun + 104
    22  UIKit                               0x01003cc1 UIApplicationMain + 160
    23  to-do list                          0x000ca10c main + 140
    24  libdyld.dylib                       0x02ea2a21 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)*

A:

The error is not in the code you posted above. In the console message it states: 

'Pushing a navigation controller is not supported'

Check your storyboard file to make sure everything is setup correctly. 

