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344 lines
13 KiB
344 lines
13 KiB
4 years ago
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//
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// ImageCache.swift
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//
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// Copyright (c) 2015 Alamofire Software Foundation (http://alamofire.org/)
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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import Alamofire
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import Foundation
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#if os(iOS) || os(tvOS) || os(watchOS)
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import UIKit
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#elseif os(macOS)
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import Cocoa
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#endif
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// MARK: ImageCache
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/// The `ImageCache` protocol defines a set of APIs for adding, removing and fetching images from a cache.
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public protocol ImageCache {
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/// Adds the image to the cache with the given identifier.
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func add(_ image: Image, withIdentifier identifier: String)
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/// Removes the image from the cache matching the given identifier.
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func removeImage(withIdentifier identifier: String) -> Bool
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/// Removes all images stored in the cache.
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@discardableResult
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func removeAllImages() -> Bool
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/// Returns the image in the cache associated with the given identifier.
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func image(withIdentifier identifier: String) -> Image?
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}
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/// The `ImageRequestCache` protocol extends the `ImageCache` protocol by adding methods for adding, removing and
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/// fetching images from a cache given an `URLRequest` and additional identifier.
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public protocol ImageRequestCache: ImageCache {
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/// Adds the image to the cache using an identifier created from the request and identifier.
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func add(_ image: Image, for request: URLRequest, withIdentifier identifier: String?)
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/// Removes the image from the cache using an identifier created from the request and identifier.
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func removeImage(for request: URLRequest, withIdentifier identifier: String?) -> Bool
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/// Returns the image from the cache associated with an identifier created from the request and identifier.
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func image(for request: URLRequest, withIdentifier identifier: String?) -> Image?
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}
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// MARK: -
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/// The `AutoPurgingImageCache` in an in-memory image cache used to store images up to a given memory capacity. When
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/// the memory capacity is reached, the image cache is sorted by last access date, then the oldest image is continuously
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/// purged until the preferred memory usage after purge is met. Each time an image is accessed through the cache, the
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/// internal access date of the image is updated.
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open class AutoPurgingImageCache: ImageRequestCache {
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class CachedImage {
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let image: Image
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let identifier: String
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let totalBytes: UInt64
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var lastAccessDate: Date
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init(_ image: Image, identifier: String) {
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self.image = image
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self.identifier = identifier
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lastAccessDate = Date()
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totalBytes = {
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#if os(iOS) || os(tvOS) || os(watchOS)
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let size = CGSize(width: image.size.width * image.scale, height: image.size.height * image.scale)
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#elseif os(macOS)
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let size = CGSize(width: image.size.width, height: image.size.height)
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#endif
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let bytesPerPixel: CGFloat = 4.0
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let bytesPerRow = size.width * bytesPerPixel
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let totalBytes = UInt64(bytesPerRow) * UInt64(size.height)
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return totalBytes
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}()
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}
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func accessImage() -> Image {
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lastAccessDate = Date()
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return image
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}
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}
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// MARK: Properties
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/// The current total memory usage in bytes of all images stored within the cache.
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open var memoryUsage: UInt64 {
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var memoryUsage: UInt64 = 0
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synchronizationQueue.sync(flags: [.barrier]) { memoryUsage = self.currentMemoryUsage }
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return memoryUsage
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}
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/// The total memory capacity of the cache in bytes.
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public let memoryCapacity: UInt64
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/// The preferred memory usage after purge in bytes. During a purge, images will be purged until the memory
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/// capacity drops below this limit.
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public let preferredMemoryUsageAfterPurge: UInt64
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private let synchronizationQueue: DispatchQueue
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private var cachedImages: [String: CachedImage]
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private var currentMemoryUsage: UInt64
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// MARK: Initialization
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/// Initializes the `AutoPurgingImageCache` instance with the given memory capacity and preferred memory usage
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/// after purge limit.
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///
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/// Please note, the memory capacity must always be greater than or equal to the preferred memory usage after purge.
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///
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/// - parameter memoryCapacity: The total memory capacity of the cache in bytes. `100 MB` by default.
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/// - parameter preferredMemoryUsageAfterPurge: The preferred memory usage after purge in bytes. `60 MB` by default.
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///
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/// - returns: The new `AutoPurgingImageCache` instance.
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public init(memoryCapacity: UInt64 = 100_000_000, preferredMemoryUsageAfterPurge: UInt64 = 60_000_000) {
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self.memoryCapacity = memoryCapacity
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self.preferredMemoryUsageAfterPurge = preferredMemoryUsageAfterPurge
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precondition(memoryCapacity >= preferredMemoryUsageAfterPurge,
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"The `memoryCapacity` must be greater than or equal to `preferredMemoryUsageAfterPurge`")
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cachedImages = [:]
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currentMemoryUsage = 0
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synchronizationQueue = {
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let name = String(format: "org.alamofire.autopurgingimagecache-%08x%08x", arc4random(), arc4random())
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return DispatchQueue(label: name, attributes: .concurrent)
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}()
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#if os(iOS) || os(tvOS)
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let notification = UIApplication.didReceiveMemoryWarningNotification
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NotificationCenter.default.addObserver(self,
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selector: #selector(AutoPurgingImageCache.removeAllImages),
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name: notification,
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object: nil)
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#endif
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}
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deinit {
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NotificationCenter.default.removeObserver(self)
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}
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// MARK: Add Image to Cache
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/// Adds the image to the cache using an identifier created from the request and optional identifier.
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///
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/// - parameter image: The image to add to the cache.
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/// - parameter request: The request used to generate the image's unique identifier.
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/// - parameter identifier: The additional identifier to append to the image's unique identifier.
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open func add(_ image: Image, for request: URLRequest, withIdentifier identifier: String? = nil) {
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let requestIdentifier = imageCacheKey(for: request, withIdentifier: identifier)
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add(image, withIdentifier: requestIdentifier)
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}
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/// Adds the image to the cache with the given identifier.
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///
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/// - parameter image: The image to add to the cache.
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/// - parameter identifier: The identifier to use to uniquely identify the image.
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open func add(_ image: Image, withIdentifier identifier: String) {
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synchronizationQueue.async(flags: [.barrier]) {
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let cachedImage = CachedImage(image, identifier: identifier)
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if let previousCachedImage = self.cachedImages[identifier] {
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self.currentMemoryUsage -= previousCachedImage.totalBytes
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}
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self.cachedImages[identifier] = cachedImage
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self.currentMemoryUsage += cachedImage.totalBytes
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}
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synchronizationQueue.async(flags: [.barrier]) {
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if self.currentMemoryUsage > self.memoryCapacity {
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let bytesToPurge = self.currentMemoryUsage - self.preferredMemoryUsageAfterPurge
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var sortedImages = self.cachedImages.map { $1 }
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sortedImages.sort {
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let date1 = $0.lastAccessDate
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let date2 = $1.lastAccessDate
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return date1.timeIntervalSince(date2) < 0.0
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}
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var bytesPurged = UInt64(0)
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for cachedImage in sortedImages {
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self.cachedImages.removeValue(forKey: cachedImage.identifier)
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bytesPurged += cachedImage.totalBytes
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if bytesPurged >= bytesToPurge {
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break
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}
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}
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self.currentMemoryUsage -= bytesPurged
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}
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}
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}
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// MARK: Remove Image from Cache
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/// Removes the image from the cache using an identifier created from the request and optional identifier.
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///
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/// - parameter request: The request used to generate the image's unique identifier.
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/// - parameter identifier: The additional identifier to append to the image's unique identifier.
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///
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/// - returns: `true` if the image was removed, `false` otherwise.
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@discardableResult
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open func removeImage(for request: URLRequest, withIdentifier identifier: String?) -> Bool {
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let requestIdentifier = imageCacheKey(for: request, withIdentifier: identifier)
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return removeImage(withIdentifier: requestIdentifier)
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}
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/// Removes all images from the cache created from the request.
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///
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/// - parameter request: The request used to generate the image's unique identifier.
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///
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/// - returns: `true` if any images were removed, `false` otherwise.
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@discardableResult
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open func removeImages(matching request: URLRequest) -> Bool {
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let requestIdentifier = imageCacheKey(for: request, withIdentifier: nil)
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var removed = false
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synchronizationQueue.sync(flags: [.barrier]) {
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for key in self.cachedImages.keys where key.hasPrefix(requestIdentifier) {
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if let cachedImage = self.cachedImages.removeValue(forKey: key) {
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self.currentMemoryUsage -= cachedImage.totalBytes
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removed = true
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}
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}
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}
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return removed
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}
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/// Removes the image from the cache matching the given identifier.
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///
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/// - parameter identifier: The unique identifier for the image.
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///
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/// - returns: `true` if the image was removed, `false` otherwise.
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@discardableResult
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open func removeImage(withIdentifier identifier: String) -> Bool {
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var removed = false
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synchronizationQueue.sync(flags: [.barrier]) {
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if let cachedImage = self.cachedImages.removeValue(forKey: identifier) {
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self.currentMemoryUsage -= cachedImage.totalBytes
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removed = true
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}
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}
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return removed
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}
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/// Removes all images stored in the cache.
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///
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/// - returns: `true` if images were removed from the cache, `false` otherwise.
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@discardableResult @objc
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open func removeAllImages() -> Bool {
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var removed = false
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synchronizationQueue.sync(flags: [.barrier]) {
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if !self.cachedImages.isEmpty {
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self.cachedImages.removeAll()
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self.currentMemoryUsage = 0
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removed = true
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}
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}
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return removed
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}
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// MARK: Fetch Image from Cache
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/// Returns the image from the cache associated with an identifier created from the request and optional identifier.
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///
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/// - parameter request: The request used to generate the image's unique identifier.
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/// - parameter identifier: The additional identifier to append to the image's unique identifier.
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///
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/// - returns: The image if it is stored in the cache, `nil` otherwise.
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open func image(for request: URLRequest, withIdentifier identifier: String? = nil) -> Image? {
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let requestIdentifier = imageCacheKey(for: request, withIdentifier: identifier)
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return image(withIdentifier: requestIdentifier)
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}
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/// Returns the image in the cache associated with the given identifier.
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///
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/// - parameter identifier: The unique identifier for the image.
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///
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/// - returns: The image if it is stored in the cache, `nil` otherwise.
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open func image(withIdentifier identifier: String) -> Image? {
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var image: Image?
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synchronizationQueue.sync(flags: [.barrier]) {
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if let cachedImage = self.cachedImages[identifier] {
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image = cachedImage.accessImage()
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}
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}
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return image
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}
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// MARK: Image Cache Keys
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/// Returns the unique image cache key for the specified request and additional identifier.
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///
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/// - parameter request: The request.
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/// - parameter identifier: The additional identifier.
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///
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/// - returns: The unique image cache key.
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open func imageCacheKey(for request: URLRequest, withIdentifier identifier: String?) -> String {
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var key = request.url?.absoluteString ?? ""
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if let identifier = identifier {
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key += "-\(identifier)"
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}
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return key
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}
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}
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