// The MIT License (MIT)

//

// Copyright (c) 2014 Nate Lyman (https://github.com/natelyman/SwiftImageLoader)

//

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included in all

// copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

// SOFTWARE.

import UIKit

import Foundation

public class ImageLoader {

var cache = NSCache<NSString, NSData>()

public class var sharedLoader : ImageLoader {

struct Static {

static let instance : ImageLoader = ImageLoader()

}

return Static.instance

}

public func imageForUrl(urlString: String, completionHandler: @escaping(_ image: UIImage?, _ url: String) -> ()) {

DispatchQueue.global(qos: DispatchQoS.QoSClass.background).async {

var data: NSData?

if let dataCache = self.cache.object(forKey: urlString as NSString){

data = (dataCache) as NSData

}else{

if (URL(string: urlString) != nil)

{

data = NSData(contentsOf: URL(string: urlString)!)

}else{

return

}

}

if let goodData = data {

let image = UIImage(data: goodData as Data)

DispatchQueue.main.async(execute: {() in

completionHandler(image, urlString)

})

return

}

let downloadTask: URLSessionDataTask = URLSession.shared.dataTask(with: URL(string: urlString)!, completionHandler: { (data, response, error) -> Void in

if (error != nil) {

completionHandler(nil, urlString)

return

}

if data != nil {

let image = UIImage(data: data!)

self.cache.setObject(data! as NSData, forKey: urlString as NSString)

DispatchQueue.main.async(execute: {() in

completionHandler(image, urlString)

})

return

}

})

downloadTask.resume()

}

}

}