X code7 error trying to do PageViewController - swift

Question

In my main storyboard i have my firstViewController then secondViewController and my pageViewController is third.
I am connecting all of them using seque Modal.
First and Second is working but my third is showing me an error.
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Storyboard (<UIStoryboard: 0x7fb15bca4dd0>) doesn't contain a view controller with identifier 'FirstViewController''
*** First throw call stack:
(
0 CoreFoundation 0x0000000108ba7f65 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010aa62deb objc_exception_throw + 48
2 UIKit 0x0000000109ccc5d4 -[UIStoryboard instantiateInitialViewController] + 0
3 0x00000001089b422d _TFC8test23SkillPageViewControllerP33_B1A346F97B9DE8BA73F8676576C06E1324newColoredViewControllerfS0_FSSCSo16UIViewController + 365
4 0x00000001089b65cc _TFFC8test23SkillPageViewControllerg22orderedViewControllersGSaCSo16UIViewController_U_FT_GSaS1__ + 92
5 0x00000001089b2f75 _TFC8test23SkillPageViewControllerg22orderedViewControllersGSaCSo16UIViewController_ + 325
6 0x00000001089b3229 _TFC8test23SkillPageViewController11viewDidLoadfS0_FT_T_ + 313
7 0x00000001089b35e2 _TToFC8test23SkillPageViewController11viewDidLoadfS0_FT_T_ + 34
8 UIKit 0x0000000109775931 -[UIViewController loadViewIfRequired] + 1344
9 UIKit 0x0000000109775c7d -[UIViewController view] + 27
10 UIKit 0x0000000109edbb2c -[_UIFullscreenPresentationController _setPresentedViewController:] + 87
11 UIKit 0x000000010974603a -[UIPresentationController initWithPresentedViewController:presentingViewController:] + 133
12 UIKit 0x00000001097885c4 -[UIViewController _presentViewController:withAnimationController:completion:] + 3930
13 UIKit 0x000000010978b878 -[UIViewController _performCoordinatedPresentOrDismiss:animated:] + 489
14 UIKit 0x000000010978b387 -[UIViewController presentViewController:animated:completion:] + 179
15 UIKit 0x0000000109ce2af3 __67-[UIStoryboardModalSegueTemplate newDefaultPerformHandlerForSegue:]_block_invoke + 243
16 UIKit 0x0000000109cd1189 -[UIStoryboardSegueTemplate _performWithDestinationViewController:sender:] + 460
17 UIKit 0x0000000109cd0f8c -[UIStoryboardSegueTemplate _perform:] + 82
18 UIKit 0x0000000109cd1250 -[UIStoryboardSegueTemplate perform:] + 156
19 UIKit 0x00000001095ec1fa -[UIApplication sendAction:to:from:forEvent:] + 92
20 UIKit 0x0000000109750504 -[UIControl sendAction:to:forEvent:] + 67
21 UIKit 0x00000001097507d0 -[UIControl _sendActionsForEvents:withEvent:] + 311
22 UIKit 0x000000010974f906 -[UIControl touchesEnded:withEvent:] + 601
23 UIKit 0x0000000109656aa3 -[UIWindow _sendTouchesForEvent:] + 835
24 UIKit 0x0000000109657691 -[UIWindow sendEvent:] + 865
25 UIKit 0x0000000109609752 -[UIApplication sendEvent:] + 263
26 UIKit 0x00000001095e4fcc _UIApplicationHandleEventQueue + 6693
27 CoreFoundation 0x0000000108ad40a1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
28 CoreFoundation 0x0000000108ac9fcc __CFRunLoopDoSources0 + 556
29 CoreFoundation 0x0000000108ac9483 __CFRunLoopRun + 867
30 CoreFoundation 0x0000000108ac8e98 CFRunLoopRunSpecific + 488
31 GraphicsServices 0x000000010e099ad2 GSEventRunModal + 161
32 UIKit 0x00000001095ea676 UIApplicationMain + 171
33 0x00000001089ba10d main + 109
34 libdyld.dylib 0x000000010b58192d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

It is a hard guess because you didn't provide any of you code, but as the error state,
You need to set identifier for the view controller you used,in Storyboard > ViewController(one you added to storyboard,I think it is FirstViewController)>attribute inspector
there something called storyboard identifier or something like this, you need to set it. as I see you need to name it "FirstViewController"
I think you are skipping some main steps of configuring a pageviewcontroller, there is a very good tutorial here
it would be very helpful, if you check this tutorial