LoadableViews.swift

protocol LoaderViewType: UIView {
    func startAnimating()
    func stopAnimating()
}

class LoaderButton: UIButton, LoaderViewType {
    
    fileprivate let activityLoader: UIActivityIndicatorView = {
        let indicator = UIActivityIndicatorView(style: .gray)
        indicator.translatesAutoresizingMaskIntoConstraints = false
        indicator.widthAnchor.constraint(equalToConstant: buttonWidth).isActive = true
        return indicator
    }()
    
    private static let buttonWidth: CGFloat = 30
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupView()
    }
    
    private func setupView(){
        let contentView = self
        contentView.addSubview(activityLoader)
        activityLoader.boundInside(superView: contentView, unpin: .left)
    }
    
    
    func startAnimating(){
        self.contentEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: (type(of: self)).buttonWidth)
        activityLoader.startAnimating()
    }
    func stopAnimating(){
        self.contentEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        activityLoader.stopAnimating()
    }
    
    
}