Display activity indicator inside UIButton

Question

I would like to change the content of a UIButton to an ActivityIndicator after it is pressed.

I know buttons have an imageView and a titleLabel, but I don\'t know how to

Answer 1

Updated selected answer( steve-rosenberg ) for Apple Swift version 3.0.1 (swiftlang-800.0.58.6 clang-800.0.42.1) Xcode 8.1 (8B62)

import ObjectiveC

private var originalButtonText: String?
private var activityIndicator: UIActivityIndicatorView!

extension UIButton{

    func showLoading() {
        originalButtonText = self.titleLabel?.text
        self.setTitle("", for: .normal)

        if (activityIndicator == nil) {
            activityIndicator = createActivityIndicator()
        }

        showSpinning()
    }

    func hideLoading() {
        self.setTitle(originalButtonText, for: .normal)
        activityIndicator.stopAnimating()
    }

    private func createActivityIndicator() -> UIActivityIndicatorView {
        let activityIndicator = UIActivityIndicatorView()
        activityIndicator.hidesWhenStopped = true
        activityIndicator.color = UIColor.lightGray
        return activityIndicator
    }

    func showSpinning() {
        activityIndicator.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(activityIndicator)
        centerActivityIndicatorInButton()
        activityIndicator.startAnimating()
    }

    private func centerActivityIndicatorInButton() {
        let xCenterConstraint = NSLayoutConstraint(item: self, attribute: .centerX, relatedBy: .equal, toItem: activityIndicator, attribute: .centerX, multiplier: 1, constant: 0)
        self.addConstraint(xCenterConstraint)

        let yCenterConstraint = NSLayoutConstraint(item: self, attribute: .centerY, relatedBy: .equal, toItem: activityIndicator, attribute: .centerY, multiplier: 1, constant: 0)
        self.addConstraint(yCenterConstraint)
    }
}