How to assign values from array to buttons in Swift

When connecting the buttons to the code, connect them as an Outlet Connection. Then you will have an array of buttons. To set the button text accordingly:

for button in buttons {
    button.setTitle(emoji[buttons.index(of: button)!], for: [])
}

This will loop through all the buttons and set their title to the corresponding emojis. You can look at how to shuffle an array to randomize the emoji: How do I shuffle an array in Swift?

Assuming you've added buttons to a view e.g. via interface builder you can do something like this. There are a lot of examples on how to sort the emoji array elsewhere.

class ViewController: UIViewController {

    let emoji = ["🦁","🦁", "🐶","🐶", "🐱", "🐱", "🐭", "🐭", "🐹", "🐹", "🐰", "🐰", "🐻", "🐻", "🐼", "🐼", "🐨", "🐨", "🐯","🐯", "🐮", "🐮", "🐷", "🐷"]

    override func viewDidLoad() {
        super.viewDidLoad()
        let buttons: [UIButton] = view.subviews.flatMap { $0 as? UIButton }
        guard buttons.count <= emoji.count else {
            fatalError("Not enough emoji for buttons")
        }
        // sort emoji here
        _ = buttons.enumerated().map {  (index, element) in
            element.setTitle(emoji[index], for: .normal)
        }
    }
}

This solution leverages shuffled() and zip()

class MyViewController: UIViewController {

    // Add the face buttons to the collection in the storyboard
    @IBOutlet var faceButtons: [UIButton]!
    let faces = ["🦁","🦁", "🐶","🐶", "🐱", "🐱", "🐭", "🐭", "🐹", "🐹", "🐰", "🐰", "🐻", "🐻", "🐼", "🐼", "🐨", "🐨", "🐯","🐯", "🐮", "🐮", "🐷", "🐷"]

    func randomizeFaces() {
        // zip() combines faceButtons and faces, shuffled() randomizes faces
        zip(faceButtons, faces.shuffled()).forEach { faceButtton, face in
            faceButtton.setTitle(face, for: .normal)
        }
    }

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

}

Here is the definition of shuffled() from: How do I shuffle an array in Swift?

extension MutableCollection where Indices.Iterator.Element == Index {
    /// Shuffles the contents of this collection.
    mutating func shuffle() {
        let c = count
        guard c > 1 else { return }

        for (firstUnshuffled , unshuffledCount) in zip(indices, stride(from: c, to: 1, by: -1)) {
            let d: IndexDistance = numericCast(arc4random_uniform(numericCast(unshuffledCount)))
            guard d != 0 else { continue }
            let i = index(firstUnshuffled, offsetBy: d)
            swap(&self[firstUnshuffled], &self[i])
        }
    }
}

extension Sequence {
    /// Returns an array with the contents of this sequence, shuffled.
    func shuffled() -> [Iterator.Element] {
        var result = Array(self)
        result.shuffle()
        return result
    }
}