What is the difference between ViewController and UiViewController - swift

I am trying to understand what is the difference between these two concepts.
When I speak about a controller in main.storyboard, do I mean UiViewController or ViewController? are they the same or complementary?
I tried to find some information but got mixed results, I would like you to explain it to me

UIViewController is a class in the UIKit framework. Thing that controls a UIView (aka "view controllers") inherit from UIViewController.
If you create a new iOS app project in Xcode, and choose to use UIKit as the UI framework, it will generate a class called ViewController as part of the project template.
class ViewController: UIViewController {
This ViewController is a view controller, so it inherits from UIViewController. Note that ViewController is just a random name for the view controller that Xcode chose, it could just as well be YourAppViewController or even FooBarBaz.
You can also find view controllers in the storyboard. Those are the yellow circles with a white square inside. If you have just created a new project, the only one there would be the ViewController Xcode generated. You can see which view controller class a view controller in the storyboard corresponds to by selecting it and checking the "Class" field in the identity inspector:
That iPhone-looking part is the UIView that it controls.


Cannot add Outlet connection from Button to ViewController

I am trying to create an IBOutlet connection/reference from my button to my UIViewController in Xcode, but it is only giving me the "option" to add an Action connection. I am trying to utilize the viewDidLoad and baselineAdjustment to vertically center the buttons label when the text scales to fit the width, but am not having any luck.
Does anyone have a suggestion or know what I'm doing wrong?
EDIT: Adding a few more screenshots for clarity
If I select my main Scene View, the class is of type ViewController. If I select the view that the Button in question is a part of(it is in a ContainerView), it is of class UIViewController and the options do not present a choice of ViewController.
Make sure the right class subclassing the UIViewController, make sure when you are doing it, you choosing the UIViewController and not the View or the safe area.
Let me know if it solved it
I see the you have multiple ViewControllers in storyboard. Ideally, each View controller in the storyboard is supposed to be of only one type of UIViewController implementation and it's also true the other way around. so, If you have say 3 UIViewControllers in Your storyBoard, then you will need to create 3 .swift files which implement UIViewController like so:
abcVC:UIViewController { .....
efgVC:UIViewController { .....
ViewController:UIViewController { ..... //this is the default one you get.
and then set the class of each ViewController in your storyboard to one of each of the above.
if your ViewController which has the button you want to outlet has a class type abcVC, then you can outlet your button only in abcVc's implementation in abcVC.swift.
Hope it makes sense. to see how to set class, refer #Vadim F. 's answer.
and if you happen to upvote this answer, please also consider upvoting #Vadim F. 's answer.
This is how you can crate a new .swift file while subclassing a UIViewController: File -> new -> File -> Cocoa touch class -> #make it subclass of UIViewController and give it a unique name eg: abcVC
Certify that your ViewController in the Storyboard is of the class ViewController (i.e your view controller) and not from UIViewController.

iOS & Swift: ViewController class is defined, but when is it created as an object?

Learning Swift as my first new language in many years, I've come across something I'm curious about using Xcode and creating a new iOS project using the single view template.
In the default ViewController.swift file, UIkit is imported, and then the class ViewController is defined, inheriting from UIViewController. But I can't seem to find out where or how this class is ever created or initialized as an object.
Default ViewController.swift example
If I define my own class, or even want to create another view controller, I must first initialize it as an object somewhere in order to use it. So where is this default ViewController getting made?
Thanks for any help you can offer for me to try to conceptualize this!
Open your "Main.storyboard" file. Make sure View Controller is selected on the left sidebar:
Then on the right sidebar you can see that your ViewController class is in the class field:
So, when your app is loaded, the default storyboard is loaded, and that storyboard is responsible for creating an instance of the ViewController class and set it up for you. To test this out, you could create a new class, say ViewController2 and make it inherit from UIViewController. ViewController2 would then be available in the right sidebar:
And then your ViewController2 code will be used instead of ViewController.
You have changed the location of the ViewControllerQuestion.app file
I believe that the UIApplicationDelegate takes care of the creation of the initial view controller. You still can manually create view controllers as you mentioned and segue to them.
Normally you can create a view controller in a storyboard and use the Interface Builder to set up a segue to that view controller.
I hope this answers your question.

Connecting an NSTextField object to an IBOutlet in AppDelegate.swift

Recently, I've been trying to learn Swift, so if this seems to be a relatively simple question do forgive me.
For some reason, control-clicking a NSTextField object in a tab view controller and dragging doesn't give me the option to "insert outlet or action" but rather, "connect binding" when I scroll over a compatible object (in this case it was the superclass declaration).
Why is it that I am not able to insert an outlet or an action, but am able to connect a binding?
side question: what is a binding?
The outlet can only be a property of your nib file / storyboard scene's owner. Which is your view controller in most cases.
This is what happen what your view controller instantiated from storyboard:
Instantiates views using the information in your storyboard file.
Connects all outlets and actions.
Assigns the root view to the view controller’s view property.
Calls the view controller’s awakeFromNib method.
When this method is called, the view controller’s trait collection is empty and views may not be in their final positions.
Calls the view controller’s viewDidLoad method.
Use this method to add or remove views, modify layout constraints, and load data for your views.
Short Version:
UIKit instantiate your view controller for you, and add all subview as you required in storyboard. And connect(binding) subViews to their outlet (if you created one).
How to solve your problem
When you opened your assistant editor. Choose the automatic viewController, if that is not something your create, you should create a subclass of viewController you need (in this case, UITabViewController) and change your scene's class to that.
you need to have same view controller in storyboard when you control-drag a NSTextField to controller
Edit: As Leo mentioned in the comment You can't connect/create any IBOutlet in the AppDelegate file if you are using storyboard, you have to create in it's particular controller where you have placed NSTextField
As shown in the image if you are in storyboard click the top bar on the controller from there you will get the options shown in the image, select Automatic
If you have selected proper view controller in the storyboard it should show same viewcontroller file in the Automatic(viewController.swift) by selecting that file you should able to control-drag IBOutlet
In the Xib when you select Xib and click 'Asssistant Editor' it will generally take to the proper view controller if not select Automatic for it also as shown in the Storyboard image are that you will able to connect you IBOultet
When you control-drag IBOutlet it create a connection between your control and property of view controller
From Apple Doc
The Cocoa bindings feature enables you to establish a live connection between an item of data and its presentation in a view. Any change made to the data’s value, either in the view or in the object that stores the data, automatically propagates across the connection.
You can find more information regarding it in Apple Doc

IPhone Storyboard - Assigning class to view controller in storyboard

I have created a simple app using storyboard. In storyboard file, i have dragged one view controller. I want to assign a class to the newly added view controller. To do this, I clicked on new file in Xcode, clicked on Objective c class, entered class name MyViewController and subclass is of UIViewController. I went back to storyboard and clicked on Custom class type and given MyViewController in class tab. But it is not taking this. If i unselect the viewcontroller and select, custom class shows "UIView" again.
I am using Xcode version 4.3.3 (4E3002).
xcode does this problem even if everything is fine. Close your xcode project and then quit xcode. Start again and you will be able to find the class in the dropdown menu.

Classes for new View Controller in Storyboard

In my storyboard I drag on a new View Controller. My Storyboard now has two view controllers: the main one that came when I created the file, and the one a dragged on.
When I go into the 'assistant editor' and select the main view controller, I get the ViewController.h class. But when I select the other controller I get UIViewController.h which is an Apple file.
How do I link/create these classes for each View Controller? Is there an automated way to do this, or am I not doing it right.
You need to create your own subclass of UIViewController and set the newly created view controller as the custom class in the storyboard.
Press cmd+n or go to File > New File
Select Objective-C class and hit next
Type UIViewController into the second box and type a name for the new class in the first box (which will be something like MyClassViewController)
Go into your storyboard, select the View Controller you dragged out, look at the inspector and go to the Custom Class Tab and set the custom class to your newly created view controller (e.g. MyClassViewController)