Code Examples of Creating Objects in Swift

24th March 2017

This article will look at a few code examples of creating objects in Swift 3 without using the Interface Builder. Whilst the IB in recent versions of Xcode has become more reliable and less buggy, many developers still wish to learn the code behind creating the view elements.

In addition to the Creating Elements using Code post, we look at some further elements below.

The objects can be created by adding code in the viewDidLoad function in the ViewController.swift file.

UILabel

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
        
    let label = UILabel(frame: CGRect(x: 0, y: 0, width: 200, height: 21))
    label.center = CGPoint(x: 160, y: 285)
    label.text = "This is a test label"
    label.textAlignment = .center
    self.view.addSubview(label)
}

UIButton

override func viewDidLoad() {
    super.viewDidLoad()
    
    ....
 
    // Button
    let button = UIButton(frame: CGRect(x: 0, y: 0, width: 150, height: 44))
    button.center = CGPoint(x: 160, y: 200)
    button.setTitle("Click Me!", for: .normal)
    button.backgroundColor = UIColor.red
    button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
        
    self.view.addSubview(button)
}

With the UIButton code, the addTarget function requires an action function to also be defined.

In the code example above, a buttonAction function should be defined.

func buttonAction(){
   //...
}

UISwitch

override func viewDidLoad() {
    super.viewDidLoad()
    
    ....
 
    let switchDemo = UISwitch(frame: CGRect(x: 150, y: 300, width: 0, height: 0))
    switchDemo.isOn = true
    switchDemo.setOn(true, animated: false)
    switchDemo.addTarget(self, action: #selector(switchChange), for: .valueChanged)
        
    self.view.addSubview(switchDemo)
}

func switchChange() {
    //...
}

UIAlertController

override func viewDidLoad() {
    super.viewDidLoad()
    
    ....

    let alertController = UIAlertController(title: "Alert", message: "Here is an alert", preferredStyle: UIAlertControllerStyle.alert)
        
    let destructiveAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.destructive) {
        (result : UIAlertAction) -> Void in
    }
        
    let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default) {
        (result : UIAlertAction) -> Void in
    }
        
    alertController.addAction(destructiveAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

UINavigationBar

override func viewDidLoad() {
    super.viewDidLoad()

    ....

    let navBar: UINavigationBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: 320, height: 44))
    self.view.addSubview(navBar);
}

UINavigationItem

override func viewDidLoad() {
    super.viewDidLoad()

    ....

    let navItem = UINavigationItem(title: "SomeTitle");
    let doneItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.done, target: nil, action: #selector(menuItemAction));
    navItem.rightBarButtonItem = doneItem;
    navBar.setItems([navItem], animated: false);
}

func menuItemAction() {
    //...        
}

UISlider

override func viewDidLoad() {
    super.viewDidLoad()

    ....

    let sliderDemo = UISlider(frame:CGRect(x: 20, y: 260, width: 280, height: 20))
    sliderDemo.minimumValue = 0
    sliderDemo.maximumValue = 100
    sliderDemo.isContinuous = true
    sliderDemo.tintColor = UIColor.red
    sliderDemo.value = 50
    sliderDemo.addTarget(self, action: #selector(sliderValueDidChange), for: .valueChanged)
    self.view.addSubview(sliderDemo)
}

func sliderValueDidChange() {
    //...      
}

Note: This article is based on iOS 10 and Swift version 3.