64 lines
1.8 KiB
Swift
64 lines
1.8 KiB
Swift
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//
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// ImageCache.swift
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// Tusker
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//
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// Created by Shadowfactson 8/21/18.
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// Copyright © 2018 Shadowfacts. All rights reserved.
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//
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import UIKit
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class AvatarCache {
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static let shared = AvatarCache()
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let cache = NSCache<NSString, UIImage>()
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var requests = [URL: URLSessionDataTask]()
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var requestCallbacks = [URL: [(UIImage?) -> Void]]()
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private init() {
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}
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func get(_ url: URL, completion: @escaping (UIImage?) -> Void) {
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let key = url.absoluteString as NSString
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if let image = cache.object(forKey: key) {
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completion(image)
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} else if var callbacks = requestCallbacks[url] {
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callbacks.append(completion)
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requestCallbacks[url] = callbacks
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} else {
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requestCallbacks[url] = [completion]
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let task = URLSession.shared.dataTask(with: url) { data, response, error in
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guard error == nil,
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let data = data,
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let image = UIImage(data: data) else {
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let callbacks = self.requestCallbacks.removeValue(forKey: url)!
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for callback in callbacks {
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// todo: default avatar for failed requests
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callback(nil)
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}
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return
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}
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let callbacks = self.requestCallbacks.removeValue(forKey: url)!
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for callback in callbacks {
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callback(image)
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}
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self.cache.setObject(image, forKey: key)
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}
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task.resume()
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requests[url] = task
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}
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}
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func cancel(_ url: URL) {
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requests[url]?.cancel()
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requests.removeValue(forKey: url)
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requestCallbacks.removeValue(forKey: url)
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}
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}
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