用 Moya 处理缓存

Question

我们已经在我们的项目中实现了 Moya、RxSwift 和 Alamofire 作为 pods。

有谁知道如何使用此技术控制每个 url 请求的缓存策略？

我已经通读了 Moya 的 GitHub 页面上的很多问题，但仍然找不到任何内容。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

}

提前感谢任何专业提示:)

Answer 1

子类 MoyaProvider 并组成 requestClosure。

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
        )
    }

}

Answer 2

据我了解，"cleanest" 解决此问题的方法是使用自定义 Moya 插件。这是一个实现：

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：

应该像这样将插件添加到您的 Moya 提供程序：

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

YourMoyaTarget应该符合CachePolicyGettable，从而为每个目标定义缓存策略：

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

        default:
            return .useProtocolCachePolicy
        }
    }
}

注意：此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。这样的闭包然后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

根据@fredpi 的回答，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，您需要访问 urlRequest object/objects。如何检索 Moya 路由的 urlRequest，您可以在主题中找到。

要清除缓存，您可以使用以下代码：

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: [=11=]) }
    }
}

Answer 4

如果您也想禁用存储的 cookies

request.httpShouldHandleCookies = false

用 Moya 处理缓存

Cache Handling with Moya

swift

alamofire

moya