PromiseKit 4 - 包装委托

Posted 2023-02-24

【中文标题】PromiseKit 4 - 包装委托

【英文标题】：PromiseKit 4 - Wrap Delegation

【发布时间】：2016-10-11 01:00:44

【问题描述】：

我正在尝试使用 Promisekit 实现一个带有包装委托的单例

我设法按照这里的描述实现了这一点： https://github.com/mxcl/PromiseKit/issues/136

它有效，但承诺保留第一次调用的值。它不会更新值。

示例代码：

open class APIClient: NSObject 


    static let sharedInstance = APIClient()
    var mSocket: GCDAsyncSocket!
    var deferred = Promise<[String:Any]>.pending()
    var retainCycle: NSObject?

    override init() 
        mSocket = GCDAsyncSocket()
        super.init()
        mSocket.setDelegate(self, delegateQueue: DispatchQueue.main)
        deferred.promise.always 
            print(self)  // here we force a retain on self inside the promise object
            // it will be released once processed
        .catch  (error) in

        
    


    // MARK: - sendMessageTCP
    open func sendMessageTCP(message data:Data) -> Promise<[String:Any]> 
        mSocket.write(data, withTimeout: 10, tag: 0)
        return deferred.promise
    



extension APIClient: GCDAsyncSocketDelegate 

    public func socket(_ sock: GCDAsyncSocket, didWriteDataWithTag tag: Int) 
        sock.readData(withTimeout: -1, tag: 0)
    

    public func socket(_ sock: GCDAsyncSocket, didRead data: Data, withTag tag: Int) 
        let array = data.withUnsafeBytes 
            [UInt8](UnsafeBufferPointer(start: $0, count: data.count))
        
        let parameters: [String:Any] = [
            "status": true,
            "data": bytesToHexString(bytes: array),
            "ui_message": "Read Data"
        ]
        deferred.fulfill(parameters)
        retainCycle = nil
    

    private func bytesToHexString(bytes: [UInt8]) -> String 
        return bytes.mapString(format: "%02X", $0).joined(separator: "")
    

【参考方案1】：

Promise 只能实现一次，因此只适用于实现一次的系统。对于像套接字这样的东西，你应该使用另一种异步模式，比如完成块。