Swift swipe navigation adjusting view controller size - ios

Question

I'm trying to make a swipe navigation with view controllers instead of xib files using this tutorial : https://www.youtube.com/watch?v=3jAlg5BnYUU
I've managed to replace the xib files with view controllers but when I run the app the width of the view controllers is smaller than normal :
I don't understand as it is set identically as with the xib files. Anyone knows how to solve this?
Here is my code :
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
let vc0 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController0")
self.addChildViewController(vc0!)
self.scrollView.addSubview(vc0!.view)
vc0!.didMoveToParentViewController(self)
let vc1 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController1")
var frame1 = vc1!.view.frame
frame1.origin.x = self.view.frame.size.width
vc1!.view.frame = frame1
self.addChildViewController(vc1!)
self.scrollView.addSubview(vc1!.view)
vc1!.didMoveToParentViewController(self)
let vc2 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController2")
var frame2 = vc2!.view.frame
frame2.origin.x = self.view.frame.size.width * 2
vc2!.view.frame = frame2
self.addChildViewController(vc2!)
self.scrollView.addSubview(vc2!.view)
vc2!.didMoveToParentViewController(self)
let vc3 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController3")
var frame3 = vc3!.view.frame
frame3.origin.x = self.view.frame.size.width * 3
vc3!.view.frame = frame3
self.addChildViewController(vc3!)
self.scrollView.addSubview(vc3!.view)
vc3!.didMoveToParentViewController(self)
self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width * 4, self.view.frame.size.height - 66)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

Notice that using viewDidLoad for set frame manually is a bit risky and should be avoided since the bounds are not set. Instead use the viewDidLayoutSubviews to do that but take a look because the method is called all the time when the UI elements change including constraints.
var scrollViewAdded = false
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
if !scrollViewAdded {
self.loadSrollView()
self.scrollViewAdded = true
}
}
func loadSrollView() {
self.scrollView.pagingEnabled = true
let vc0 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController0")
self.addChildViewController(vc0!)
self.scrollView.addSubview(vc0!.view)
vc0!.didMoveToParentViewController(self)
let vc1 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController1")
var frame1 = vc1!.view.frame
frame1.origin.x = self.view.frame.size.width
vc1!.view.frame = frame1
self.addChildViewController(vc1!)
self.scrollView.addSubview(vc1!.view)
vc1!.didMoveToParentViewController(self)
let vc2 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController2")
var frame2 = vc2!.view.frame
frame2.origin.x = self.view.frame.size.width * 2
vc2!.view.frame = frame2
self.addChildViewController(vc2!)
self.scrollView.addSubview(vc2!.view)
vc2!.didMoveToParentViewController(self)
let vc3 = self.storyboard?.instantiateViewControllerWithIdentifier("ViewController3")
var frame3 = vc3!.view.frame
frame3.origin.x = self.view.frame.size.width * 3
vc3!.view.frame = frame3
self.addChildViewController(vc3!)
self.scrollView.addSubview(vc3!.view)
vc3!.didMoveToParentViewController(self)
self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width * 4, self.view.frame.size.height - 66)
}