iOS-CheckedButton.swift

import UIKit

@IBDesignable class CheckedButton: UIButton {
    
    @IBInspectable var checked: Bool = false {
        didSet {
            updateImage()
        }
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setup()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }
    
    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        setup()
    }
    
    internal func setup() {
        self.addTarget(self, action: #selector(tapped), for: .touchUpInside)
    }
    
    private func updateImage() {
        let bundle = Bundle(for: CheckedButton.self)
        let image = checked ? UIImage(named: "checked_box", in: bundle, compatibleWith:nil) : UIImage(named: "unchecked_box", in: bundle, compatibleWith:nil)
        self.setBackgroundImage(image, for: .normal)
    }
    
    /// Called each time the button is tapped, and toggles the checked property
    @objc private func tapped() {
        checked = !checked
        print("New value: \(checked)")
    }
    
}