Fatal error: unexpectedly found nil while unwrapping an Optional value

[Chris Cannon]

Hello everyone,

I wanted to first explain what I trying to do. 

I am using code from https://github.com/aubrey/SwiftPagingNav

I would like to subviews(3 different UIViewControllers) for each of the pages. 

I understand that I need to have the code look something like this:

self.view1 = self.storyboard?.instantiateInitialViewController("View1") as UIViewController

self.addChildViewController(view1)

view1.willMoveToParentViewController(self)

view1.frame = CGRectMake(0, 0, wBounds, hBounds)

           self.scrollView.addSubview(view1)

           self.scrollView.bringSubviewToFront(view1)

This code is not showing anything. Please help. 

[Joshua Dutton]

It looks like your storyboard is nil (that's the optional value you are unwrapping). Any idea why that's the case?

Your code would be safer if you checked the optional first with optional chaining like this:

if let myViewController = self.storyboard?.instantiateInitialViewController("View1") {

self.view1 = myViewController
// do stuff with it

} else {

// value was nil

}

Read this for more on optional chaining: 
https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/OptionalChaining.html

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[Chris Cannon]

Well that would make sense to do. I am sorry I am new to iOS Development.

This is what I change it to.

if let view1 = self.storyboard?.instantiateInitialViewController("View1"){

        

        self.addChildViewController(view1)

        view1.willMoveToParentViewController(self)

        view1.frame = CGRectMake(0, 0, wBounds, hBounds)

        self.scrollView.addSubview(view1)

        self.scrollView.bringSubviewToFront(view1)

        }

I am getting an error of " Type '()' does not conform to protocol 'StringLiteralConvertible' "

Why would I get that?

[Joshua Dutton]

instantiateInitialViewController() doesn't take any arguments. You are looking for instantiateViewControllerWithIdentifier(identifier: String). Next time look at the docs:

https://developer.apple.com/library/ios/documentation/uikit/reference/UIStoryboard_Class/index.html

As a new iOS developer, I recommend you get really comfortable with reading Apple's documentation. It's really extensive and is one of the best sources for learning Apple's frameworks. It's built right into XCode and also really easy to google. This book by Big Nerd Ranch is good at teaching people to use the docs while learning iOS development:

http://www.amazon.com/iOS-Programming-Ranch-Edition-Guides/dp/0321942051/ref=sr_1_1?ie=UTF8&qid=1415229883&sr=8-1&keywords=big+nerd+ranch

That edition teaches iOS development in Objective-C. You'll have to wait until they release a Swift version, but I would recommend getting the Objective-C version anyway to help you understand the majority of the iOS resources currently out there.