If I set the capacity of the disk cache to less than 5MB, It doesn't work. Through the print statement, I checked that the value of the currentDiskUsage did not rise at all, and I also checked that the image has been making network requests every time because there is no cached data even if I shut down and run the app again. I'm simply wondering why this is happening. Also, I wonder what kind of eviction policy the disk cache follows. I was so curious that I tried to find out through the link [here], but there seems to be no implementation of disk cache at all. Below is the code I used. I'm attaching it together just in case. import UIKit protocol Cacheable { func getCachedResponse( for path: String, completion: @escaping (Result<Data, CacheError>) -> Void ) func save( for path: String, data: Data ) } final class CacheManager { static let shared = CacheManager() private let imageCache: URLCache init() { imageCache = URLCache( memoryCapacity: 4 * 1024 * 1024, // 4MB diskCapacity: 4 * 1024 * 1024 // 4MB ) } } extension CacheManager: Cacheable { func getCachedResponse( for path: String, completion: @escaping (Result<Data, CacheError>) -> Void ) { if let url = URL(string: path), let cachedResponse = imageCache.cachedResponse(for: URLRequest(url: url)) { completion(.success(cachedResponse.data)) return } completion(.failure(.noCachedResponse)) } func save( for path: String, data: Data ) { guard let url = URL(string: path) else { return } let response = URLResponse( url: url, mimeType: nil, expectedContentLength: 0, textEncodingName: nil ) if let uiImage = UIImage(data: data), let compressedData = uiImage.jpegData(compressionQuality: 0.8) { #if DEBUG let formmatter = ByteCountFormatter() formmatter.allowedUnits = [.useMB] formmatter.countStyle = .file print(""" === Original size: \(formmatter.string(fromByteCount: Int64(data.count))) === Cached size: \(formmatter.string(fromByteCount: Int64(compressedData.count))) """) #endif let cachedResponse = CachedURLResponse( response: response, data: compressedData ) imageCache.storeCachedResponse( cachedResponse, for: URLRequest(url: url) ) } } }