在继续之前需要等待 Alamofire 请求完成 - Swift

Question

我有一个 Alamofire 请求作为函数的一部分，我需要在执行函数的其余部分之前完成请求。您可以在下面看到完整的功能。

@IBAction func btnScanPressed(_ sender: Any) {

    // Retrieve the QRCode content
    // By using the delegate pattern
    readerVC.delegate = self

    readerVC.completionBlock = { (result: QRCodeReaderResult?) in
        print(result?.value)

    Alamofire.request((result?.value)!).responseString { response in
        debugPrint(response)

        if let json = response.result.value {

            let returnedJSON = JSON.init(parseJSON: json);


            //TESTED -> this section does work and does update the values

            self.co.setVideoURL(url: (returnedJSON["VideoURL"].string)!)

            self.co.setDisplayText(text: returnedJSON["DisplayText"].string!)

            self.co.setHasUpdated(value: true)


            print("VARIABLES NOW SET")


        }


    } 

    }



    // Presents the readerVC as modal form sheet (This needs to happen AFTER the Alamofire has completed)
    readerVC.modalPresentationStyle = .formSheet

    present(readerVC, animated: true, completion: nil)

}

我在那里使用 swiftyJSON 来解析响应并为对象赋值。我需要在整个功能完成之前完成 Alamofire 请求。如有任何建议，我们将不胜感激！

Answer 1

基本上，您需要将 Alamofire 请求之后的代码移动到请求闭包中。请求闭包中的代码只会在请求成功完成或失败（服务器错误、超时等）后触发。以下代码应该适合您。

@IBAction func btnScanPressed(_ sender: Any) {
// Retrieve the QRCode content
// By using the delegate pattern
readerVC.delegate = self

readerVC.completionBlock = { (result: QRCodeReaderResult?) in
    print(result?.value)

Alamofire.request((result?.value)!).responseString { response in
    debugPrint(response)

    if let json = response.result.value {

        let returnedJSON = JSON.init(parseJSON: json);


        //TESTED -> this section does work and does update the values

        self.co.setVideoURL(url: (returnedJSON["VideoURL"].string)!)

        self.co.setDisplayText(text: returnedJSON["DisplayText"].string!)

        self.co.setHasUpdated(value: true)


        print("VARIABLES NOW SET")


        // Presents the readerVC as modal form sheet (This needs to happen AFTER the Alamofire has completed)
       self.readerVC.modalPresentationStyle = .formSheet

       self.present(readerVC, animated: true, completion: nil)

    }


} 

}



}

在继续之前需要等待 Alamofire 请求完成 - Swift

Need to wait for Alamofire request to complete before proceeding - Swift

grand-central-dispatch

ios

swift

alamofire