Create UIContainerView programmatically - ios

Question

I've just started to code my app in Swift 2 and avoiding the use of XIBs and storyboards.
However, I am unable to replicate the following feature. It's exactly what I wanted.
I've tried creating a UIView to perform the following using .backgroundColor and it works, however, I am unable to link it to my UIViewControllers. Just wondering how is it done? How do I link my UIView to my UIViewController?
Codes:
let subFrame : CGRect = CGRectMake(0,screenHeight*1/2.75,screenWidth,screenHeight)
var loginView = SignUpViewController()
let signUpView: UIView = UIView(frame: subFrame)
signUpView.backgroundColor = UIColor.redColor()
//Controls what each segment does
switch segmentView.indexOfSelectedSegment {
case 0:
self.view.addSubview(signUpView)
case 1:
self.view.addSubview(loginView)
default:
break;
}
I'm not even sure if .view.addSubview(xxx) overwrites/replaces the original subview if it is not this way. Is this the right way to do it?

Answer 1

Do not just start coding an app if you are not familiar with simple things of the OOP (Object-Oriented-Programming) language like Swift. This is not the way how to learn a programming language. Sure you could learn while experimenting but it is better to understand the book first before starting with more complex stuff. Read a few more pages of the Swift book from Apple. Most classes for iOS development are still Objective-C wrapped classes (reference type because the top superClass is probably NSObject; keep this in mind).
Here is the code example you wanted:
class ViewController: UIViewController {
let firstView = UIView()
let secondView = UIView()
let segmentedControlView = UISegmentedControl(items: ["firstView", "secondView"])
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor.whiteColor() // we need this for the playground
/* setup your view here */
/* add your sigment logic somewhere */
self.view.addSubview(self.segmentedControlView)
self.view.addSubview(self.firstView)
self.view.addSubview(self.secondView)
self.segmentedControlView.frame = CGRect(x: 0, y: 20, width: self.view.frame.width, height: 44)
self.segmentedControlView.selectedSegmentIndex = 0 // enable the first segment
self.segmentedControlView.addTarget(self, action: "segmentIndexChanged:", forControlEvents: UIControlEvents.ValueChanged)
/* add your own frame calculation here */
/* I prefer AutoLayout, but for the example static frames will be fine */
self.firstView.frame.origin = CGPoint(x: 0, y: self.segmentedControlView.frame.origin.y + self.segmentedControlView.frame.height)
self.firstView.frame.size = CGSize(width: self.view.frame.width, height: self.view.frame.height - self.segmentedControlView.frame.origin.y)
// to prevent same code, we just copy the same frame from the firstView
// both will sit in the same place
self.secondView.frame = self.firstView.frame
/* lets add some colors so we'll see our views */
self.firstView.backgroundColor = UIColor.blueColor()
self.secondView.backgroundColor = UIColor.redColor()
self.secondView.hidden = true // when intializer the secondView is not visible
}
func segmentIndexChanged(sender: UISegmentedControl) {
switch sender.selectedSegmentIndex {
case 0:
self.firstView.hidden = false
self.secondView.hidden = true
case 1:
self.firstView.hidden = true
self.secondView.hidden = false
default:
break;
}
}
}
If you do not understand a function, should should look up its definition in the developer docs. (Like: addSubview)