Hello!
I try to find the way to customize the caching response handler in URLSession async await methods.
When I call the async await URLSession data method func data(for request: URLRequest, delegate: (URLSessionTaskDelegate)? = nil) async throws -> (Data, URLResponse) with delegate parameter, the cache handler delegate method is not called.
On the other hand, when I call URLSession data task method func dataTask(with request: URLRequest) -> URLSessionDataTask and set the delegate instance in it with same condition, the cache handler delegate method is called as I expected.
Does anyone understand what happens here and how to customize cache handling in async await?
Supplement: In async await case, after first request I put CachePolicy.returnCacheDataDontLoad in the URLRequest instance and try another.Then I get the cache response. So even though the cache handler is not called, default caching seems to work well.
Here's the code.
Base code
import UIKit
// create URL Request and URL Session
let apiUrl:URL = URL(string: "https://api.github.com/search/repositories?q=swift")!
var urlRequest:URLRequest = .init(url: apiUrl)
let session = URLSession.init(configuration: .default)
// Simple Delegate Implementation to check what delegate method is called.
class Delegate: NSObject, URLSessionDataDelegate {
func urlSession(_ session: URLSession, didCreateTask task: URLSessionTask) {
print("didCreateTask")
}
func urlSession(_ session: URLSession, task: URLSessionTask, didFinishCollecting metrics: URLSessionTaskMetrics) {
print("didCollectMetrics")
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
if let error {
print("didCompletionWithError")
return
}
print("didcompletion")
}
//DataTask
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
print("didReceiveData")
}
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, willCacheResponse proposedResponse: CachedURLResponse) async -> CachedURLResponse? {
print("willlcache")
return proposedResponse
}
}
The dataTask case(The cache handler is called).
let task = session.dataTask(with: urlRequest)
task.delegate = Delegate()
task.resume()
The async await data method case(The cache handler is not called).
Task {
do {
let (data, response) = try await session.data(for: urlRequest, delegate: Delegate())
print(data)
print(response)
} catch {
print(error)
}
}
Thank you for your help!
