Change the text of UINavigationController not working in Swift - ios

Question

I have an app which has 5 UIViewControllers and the rootViewController is attached to a UINavigationController and the others are connected by segues. Now, I want to add a title to the UINavigationController. I have tried different things in viewDidLoad and viewDidAppear:
self.text = "Hello" // Runtime Error
self.navigationController?.navigationBar.topItem?.title = "Hello" // Runtime Error
self.navigationController?.visibleViewController.title = "Hello" // Runtime Error
The UIViewController that I am calling this is like this:
class LoginTypeActivityViewController: PPViewController{
}
Where, PPViewController is declared like this:
class PPViewController: UIViewController{
}
The runtime error is:
2014-10-13 17:21:27.878 mobilepay[29387:1382271] -[Swift._NSContiguousString set]: unrecognized selector sent to instance 0x7b6b33d0
2014-10-13 17:21:27.881 mobilepay[29387:1382271] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Swift._NSContiguousString set]: unrecognized selector sent to instance 0x7b6b33d0'
*** First throw call stack:
(
0 CoreFoundation 0x00bb5df6 __exceptionPreprocess + 182
1 libobjc.A.dylib 0x0083fa97 objc_exception_throw + 44
2 CoreFoundation 0x00bbda75 -[NSObject(NSObject) doesNotRecognizeSelector:] + 277
3 CoreFoundation 0x00b069c7 ___forwarding___ + 1047
4 CoreFoundation 0x00b0658e _CF_forwarding_prep_0 + 14
5 UIFoundation 0x067eeb91 __NSStringDrawingEngine + 29221
6 UIFoundation 0x067e784d -[NSString(NSExtendedStringDrawing) drawWithRect:options:attributes:context:] + 171
7 UIKit 0x013be151 -[UILabel _drawTextInRect:baselineCalculationOnly:] + 6626
8 UIKit 0x013bbe30 -[UILabel drawTextInRect:] + 581
9 UIKit 0x013be256 -[UILabel drawRect:] + 98
10 UIKit 0x0123354b -[UIView(CALayerDelegate) drawLayer:inContext:] + 519
11 QuartzCore 0x01077d51 -[CALayer drawInContext:] + 118
12 QuartzCore 0x01077c87 _ZL16backing_callbackP9CGContextPv + 96
13 QuartzCore 0x00f5c7ae CABackingStoreUpdate_ + 2788
14 QuartzCore 0x01077c1f ___ZN2CA5Layer8display_Ev_block_invoke + 93
15 QuartzCore 0x010ad406 x_blame_allocations + 15
16 QuartzCore 0x01077a85 _ZN2CA5Layer8display_Ev + 1591
17 QuartzCore 0x01077cd6 -[CALayer _display] + 33
18 QuartzCore 0x01077446 _ZN2CA5Layer7displayEv + 142
19 QuartzCore 0x01077cb0 -[CALayer display] + 33
20 QuartzCore 0x0106bee6 _ZN2CA5Layer17display_if_neededEPNS_11TransactionE + 322
21 QuartzCore 0x0106bf6c _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 38
22 QuartzCore 0x00fca676 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 284
23 QuartzCore 0x00fcba3c _ZN2CA11Transaction6commitEv + 392
24 QuartzCore 0x00fcc108 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92
25 CoreFoundation 0x00ad8fbe __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
26 CoreFoundation 0x00ad8f00 __CFRunLoopDoObservers + 400
27 CoreFoundation 0x00ace93a __CFRunLoopRun + 1226
28 CoreFoundation 0x00ace1ab CFRunLoopRunSpecific + 443
29 CoreFoundation 0x00acdfdb CFRunLoopRunInMode + 123
30 GraphicsServices 0x0317124f GSEventRunModal + 192
31 GraphicsServices 0x0317108c GSEventRun + 104
32 UIKit 0x011a8e16 UIApplicationMain + 1526
33 mobilepay 0x001410de top_level_code + 78
34 mobilepay 0x0014111b main + 43
35 libdyld.dylib 0x03ad7ac9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
What can be the error? I am stuck since the last 5 hours here.
I am trying to set the title different in different UIViewControllers.

Answer 1

In your viewDidLoad(), type:
title = "Hello World"