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ImageLoader.swift
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ImageLoader.swift
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// 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)!)
if data != nil {
self.cache.setObject(data!, forKey: urlString as NSString)
}
}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()
}
}
}