StackViewController/Example/ImageThumbnailView.swift at master · seedco/StackViewController · GitHub

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//
//  ImageThumbnailView.swift
//  StackViewController
//
//  Created by Indragie Karunaratne on 2016-04-24.
//  Copyright © 2016 Seed Platform, Inc. All rights reserved.
//

import UIKit
import StackViewController

protocol ImageThumbnailViewDelegate: AnyObject {
    func imageThumbnailViewDidTapDeleteButton(_ view: ImageThumbnailView)
}

open class ImageThumbnailView: UIView {
    fileprivate struct Appearance {
        static let ImageCornerRadius: CGFloat = 8.0
    }

    weak var delegate: ImageThumbnailViewDelegate?

    init(thumbnail: UIImage) {
        super.init(frame: CGRect.zero)

        let deleteButtonImage = UIImage(named: "delete-button")!
        let deleteButton = UIButton(type: .custom)
        deleteButton.translatesAutoresizingMaskIntoConstraints = false
        deleteButton.setBackgroundImage(deleteButtonImage, for: UIControl.State())
        deleteButton.addTarget(self, action: #selector(ImageThumbnailView.didTapDelete(_:)), for: .touchUpInside)

        let imageView = UIImageView(image: thumbnail)
        imageView.layer.cornerRadius = Appearance.ImageCornerRadius
        imageView.translatesAutoresizingMaskIntoConstraints = false

        addSubview(imageView)
        addSubview(deleteButton)

        let metrics = [
            "imageViewLeft": -(deleteButtonImage.size.width / 2),
            "imageViewTop": -(deleteButtonImage.size.height / 2)
        ]
        let views = [
            "deleteButton": deleteButton,
            "imageView": imageView
        ]
        let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:|[deleteButton]-imageViewTop-[imageView]|", options: [], metrics: metrics, views: views)
        let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:|[deleteButton]-imageViewLeft-[imageView]|", options: [], metrics: metrics, views: views)
        NSLayoutConstraint.activate(verticalConstraints)
        NSLayoutConstraint.activate(horizontalConstraints)
    }

    required public init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: Actions

    @objc fileprivate func didTapDelete(_ sender: UIButton) {
        delegate?.imageThumbnailViewDidTapDeleteButton(self)
    }
}