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

@Boris: This should not be in an extension.

Here it is in swift 3/4, with improved code: disables button, works with images and titles.

class LoadingButton: UIButton {

    struct ButtonState {
        var state: UIControlState
        var title: String?
        var image: UIImage?
    }

    private (set) var buttonStates: [ButtonState] = []
    private lazy var activityIndicator: UIActivityIndicatorView = {
        let activityIndicator = UIActivityIndicatorView()
        activityIndicator.hidesWhenStopped = true
        activityIndicator.color = self.titleColor(for: .normal)
        self.addSubview(activityIndicator)
        activityIndicator.translatesAutoresizingMaskIntoConstraints = false
        let xCenterConstraint = NSLayoutConstraint(item: self, attribute: .centerX, relatedBy: .equal, toItem: activityIndicator, attribute: .centerX, multiplier: 1, constant: 0)
        let yCenterConstraint = NSLayoutConstraint(item: self, attribute: .centerY, relatedBy: .equal, toItem: activityIndicator, attribute: .centerY, multiplier: 1, constant: 0)
        self.addConstraints([xCenterConstraint, yCenterConstraint])
        return activityIndicator
    }()

    func showLoading() {
        activityIndicator.startAnimating()
        var buttonStates: [ButtonState] = []
        for state in [UIControlState.disabled] {
            let buttonState = ButtonState(state: state, title: title(for: state), image: image(for: state))
            buttonStates.append(buttonState)
            setTitle("", for: state)
            setImage(UIImage(), for: state)
        }
        self.buttonStates = buttonStates
        isEnabled = false
    }

    func hideLoading() {
        activityIndicator.stopAnimating()
        for buttonState in buttonStates {
            setTitle(buttonState.title, for: buttonState.state)
            setImage(buttonState.image, for: buttonState.state)
        }
        isEnabled = true
    }

}