Tukukkk

In my code I need to send multiple HTTP POST commands to a server, depending on user selection (user picks pictures, and each command contains one picture).

I need to send first a document via HTTP POST, then n HTTP POST for the pictures and at the end a last HTTP POST to commit. Currently it is working almost fine, but if there are too many HTTP POST commands sent in // I have some HTTP errors (for instance 16 pics of 21 are sent)

Hence, I would like to make sure that each HTTP command are sent one by one to the server after the previous one has been sent successfully.

Here is the code I'm using:

            self.sendDocument{ (response) in

            if let result = response as? Bool {

                if(result == true){

                    self.Documentsent = true



                    print("Document sent, now sending photos")

                    progressDownload.progress = 0.3

                    var i = 0;

                    var j = 0;

                    //now we are sending the Photos !

                    for it in selectedPictures.sharedInstance.selectedCells{



                        let fileName = PhotoGallery.sharedInstance.photoGallery[it.item].fileName

                        self.constatImage = self.getSavedImage(named: fileName!)!



                        self.semaphore.signal()

                        self.envoiPhoto(obj: PhotoGallery.sharedInstance.photoGallery[it.item], pic: self.constatImage, num: it.item){ (result) -> () in

                            print("Envoi Photo (it.item): (result)")



                            print("i: (i), count: (selectedPictures.sharedInstance.selectedCells.count)")

                            _ = self.semaphore.wait(timeout: DispatchTime.distantFuture)

                            if(i == selectedPictures.sharedInstance.selectedCells.count-1){

                                print("for loop all pictures are sent")

                                self.allPhotosSent = true

                                self.myGroup.leave()

                            }

                            i = i+1



                        }

                        if(progressDownload.progress != 0.8){

                            progressDownload.progress += 0.2

                        }



                        j = j+1;



                    }

                }

                    //Case when document sending is failed

                else{

                    self.Constatsent = false

                }



            }

        }



        self.myGroup.notify(queue: .main, execute: {

            print("in notify: we have sent all the pictures")

            if(self.Documentsent && self.allPhotosSent){

                alertController.dismiss(animated: true, completion: ({

                    if(Constat.sharedInstance.type == "4"){

                        sleep(2)

                        self.envoiCommit()

                    }

                    self.envoiSuccess()

                }))

            }

            else{

                print("error")

                alertController.dismiss(animated: true, completion: ({

                    self.envoiError()

                }))

            }



        })

Currently I have the following behavior:

• Send HTTP POST Document


• When the HTTP POST document is finished the entire HTTP POST Photos are sent


• When the entire HTTPO POST photos are sent the HTTP POST Commit is sent.

but I would like to get HTTP POST Photo sent one by one.

How Can I achieve this ?

EDIT 1

I also tried to use semaphore and Dispatcher like this:

var i: Int = 0



    let dispatchGroup = DispatchGroup()

    let dispatchQueue = DispatchQueue(label: "test")

    let dispatchSemaphore = DispatchSemaphore(value: 0)



    DispatchQueue.main.async{

        while(i<50){

            dispatchGroup.enter()

                print("This is a synchronized closure iteration: (i)")

            self.dummyHTTPPOST{ (response) in

                if let result = response as? Bool {

                    if(result == true){

                        print("HTTP POST Sent")

                        dispatchSemaphore.signal()

                        dispatchGroup.leave()

                    }}

            }

            print("round finished")

            dispatchSemaphore.wait()

            i = i+1;



        }

    }

but the HTTP request in the method dummyHTTPPOST() is never sent....session.DataTask is never started.

I finally found a solution to send synchronously multiple HTTP POST commands using session.DataTask.

Here is the solution:

        var i: Int = 0

    let dispatchSemaphore = DispatchSemaphore(value: 0)



    DispatchQueue.global(qos: .userInitiated).async{

        while(i<500){

            self.dispatchGroup.enter()

            print("-------------------------------------------------------------------------")

                print("This is a synchronized iteration: (i)")

            self.dummyHTTPPOST{ (response) in

                if let result = response as? Bool {

                    if(result == true){

                        print("HTTP POST Sent")

                        dispatchSemaphore.signal()

                    }}

            }

            print("round finished")

            dispatchSemaphore.wait()

            if(i == 49){

                print("sent all HTTP Commands")

                self.dispatchGroup.leave()

            }

            i = i+1;



        }



        DispatchQueue.main.async {

            print("************************")

            print("everything has been sent in Dispatch Queue")

            print("************************")

        }

    }

Hope it will help other people.