APIClient v2

[kean]

I'm considering redesigning the APIClient public API for Get 1.0. It was initially designed to accommodate only the most basic scenarios, but I'd like it to be more flexible. Here is a draft of a new API.

public protocol APIClient2 {
    // No changes in these APIs, except for removal of magic `Response<Data>` and `Response<String>` support (see p3)
    func send<T: Decodable>(_ request: Request<T>) async throws -> Response<T>
    func send<T: Decodable>(_ request: Request<T?>) async throws -> Response<T?>
    @discardableResult func send(_ request: Request<Void>) async throws -> Response<Void>

    // Getting decoded response for `URL`/`URLRequest`
    func value<T: Decodable>(_ type: T.Type, for url: URL) async throws -> Response<T>
    func value<T: Decodable>(_ type: T.Type, for urlRequest: URLRequest) async throws -> Response<T>

    // Getting raw response `Data` (no decoding)
    func data(for url: URL) async throws -> Response<Data>
    func data(for urlRequest: URLRequest) async throws -> Response<Data>
    func data<T>(for request: Request<T>) async throws -> Response<Data>

    // Getting response `String` (no decoding except for .utf8 decoding)
    func string(for url: URL) async throws -> Response<String>
    func string(for urlRequest: URLRequest) async throws -> Response<String>
    func string<T>(for request: Request<T>) async throws -> Response<String>

    // (?) Add `URLSessionDataDelegate` to all APIs too for pogress reporting, etc.
    func response<T: Decodable>(for request: Request<T>, delegate: URLSessionDataDelegate) async throws -> Response<T>
}

Main Changes

1. You can now use URL and URLRequest in addition to Request
2. Pass URLSessionDataDelegate for progress reporting, per-task auth, etc.
3. Remove magic Response<Data> and Response<String> support from send(_:). If you use send(_:), they'll just use the default Decodable implementation for these types. You'll need to call data(for:) or string(for:) instead – faster, more discoverable, self-documenting

[kean]

With the new APIs, you'll be able to use URLRequest, but what if you want to, let's say, change only the cache policy?

func send<Response>(
    _ request: Request<Response>,
    cachePolicy: URLRequest.CachePolicy = .useProtocolCachePolicy
) async throws -> Response where Response: Decodable

[kean]

Another options to cover the latest requirement:

public struct RequestOptions {
    public var cachePolicy: URLRequest.CachePolicy?
    public var timeoutInterval: TimeInterval?

    // Etc
}

public protocol APIClient2 {
    public func send<T: Decodable>(
        _ request: Request<T>,
        options: RequestOptions = .init(),
        delegate: URLSessionDataDelegate? = nil
    ) async throws -> Response<T>
}

[kean]

Going with RequestOptions and also a low-level API to send URLRequest and decoding a request.