用Moya处理缓存

Question

我们在我们的项目中实现了Moya，RxSwift和Alamofire作为pod。

有人知道你是如何使用这种技术来控制每个url请求的缓存策略的吗？

我已经阅读了Moya的GitHub页面上的许多问题，但仍然没有发现任何问题。还尝试使用存储为sampleData文件的实际json响应，如下所示:

var sampleData: Data {
    guard let path = Bundle.main.path(forResource: "SampleAggregate", ofType: "txt") else {
        return "sampleData".utf8Encoded
    }
    let sample = try? String(contentsOfFile: path, encoding: String.Encoding.utf8)
    return sample!.utf8Encoded

}

null

Answer 1

基于@fredpi答案，我稍微改进了Moya的缓存插件。以下是我的版本:

import Foundation
import Moya

protocol CachePolicyGettable {
    var cachePolicy: URLRequest.CachePolicy { get }
}

final class NetworkDataCachingPlugin: PluginType {

    init (configuration: URLSessionConfiguration, inMemoryCapacity: Int, diskCapacity: Int, diskPath: String?) {
        configuration.urlCache = URLCache(memoryCapacity: inMemoryCapacity, diskCapacity: diskCapacity, diskPath: diskPath)
    }

    func prepare(_ request: URLRequest, target: TargetType) -> URLRequest {
        if let cacheableTarget = target as? CachePolicyGettable {
            var mutableRequest = request
            mutableRequest.cachePolicy = cacheableTarget.cachePolicy
            return mutableRequest
        }
        return request
    }
}

extension NetworkApiService: CachePolicyGettable {
    var cachePolicy: URLRequest.CachePolicy {
        switch self {
        case .getUserProfile:
            return .returnCacheDataElseLoad
        default:
            return .useProtocolCachePolicy
        }
    }
}

为了清除缓存，您需要具有对urlRequest object/objects的访问权限。如何检索Moya路由的urlRequest，可以在下面的主题中找到。

要清除缓存，可以使用以下代码:

public func clearCache(urlRequests: [URLRequest] = []) {
    let provider = ... // your Moya provider
    guard let urlCache = provider.manager.session.configuration.urlCache else { return }
    if urlRequests.isEmpty {
        urlCache.removeAllCachedResponses()
    } else {
        urlRequests.forEach { urlCache.removeCachedResponse(for: $0) }
    }
}

Answer 2

据我所知，解决这个问题的“最干净”的方法是使用自定义的Moya插件。下面是一个实现:

protocol CachePolicyGettable {
    var cachePolicy: URLRequest.CachePolicy { get }
}  

final class CachePolicyPlugin: PluginType {
    public func prepare(_ request: URLRequest, target: TargetType) -> URLRequest {
        if let cachePolicyGettable = target as? CachePolicyGettable {
            var mutableRequest = request
            mutableRequest.cachePolicy = cachePolicyGettable.cachePolicy
            return mutableRequest
        }

        return request
    }
}

要实际使用这个插件，还需要两个步骤:

>

let moyaProvider = MoyaProvider<YourMoyaTarget>(plugins: [CachePolicyPlugin()])

null

extension YourMoyaTarget: CachePolicyGettable {
    var cachePolicy: URLRequest.CachePolicy {
        switch self {
        case .sampleTarget, .someOtherSampleTarget:
            return .reloadIgnoringLocalCacheData

        default:
            return .useProtocolCachePolicy
        }
    }
}

注意:这种方法使用协议将缓存策略与目标类型相关联；人们也可以通过传递给插件的闭包来实现这一点。然后，这样的闭包将根据作为输入参数传递给闭包的目标类型来决定使用哪个缓存策略。

Answer 3

子类 和compose 。

它应该看起来像:

final class MyProvider<Target: TargetType>: MoyaProvider<Target> {

    public init(
        endpointClosure: @escaping EndpointClosure = MoyaProvider.defaultEndpointMapping,
        requestClosure: @escaping RequestClosure = MoyaProvider.defaultRequestMapping,
        stubClosure: @escaping StubClosure = MoyaProvider.neverStub,
        manager: Manager = MoyaProvider<Target>.defaultAlamofireManager(),
        plugins: [PluginType] = [],
        trackInflights: Bool = false
    ) {
        super.init(
            endpointClosure: endpointClosure,
            requestClosure: { endpoint, closure in
                var request = try! endpoint.urlRequest() //Feel free to embed proper error handling
                if request.url == URL(string: "http://google.com")! {
                    request.cachePolicy = .returnCacheDataDontLoad
                } else {
                    request.cachePolicy = .reloadIgnoringLocalAndRemoteCacheData
                }
                closure(.success(request))
            },
            stubClosure: stubClosure,
            manager: manager,
            plugins: plugins,
            trackInflights: trackInflights
        )
    }

}