Completion Handler

[Sub-Zero-1]

Which version of the SDK/iOS was used?

0.2.6

What problem was encountered?

I am uploading pictures to my Azure Blob Storage. I encounter wrong transfer on slow speed mobile internet connections and corrupted(not present) images on my server. The completion handler of the below function should return a fault on a unsuccessful transfer of my images, but it always gives me the answer that everything was fine!!
I am using this for payment and my customers upload their images. On success I open a payment window and my customers pay for my service. Now, I get payments, but sometimes the images are not on the server, cause of the transfer problems! I had to remove the App from App Store!!!

I can see following on slow speed mobile internet connections (EDGE) only (this never happens with high speed or WiFi connections!):

Upload progress in %: 10
DataUsageInfo(wifiReceived: 11090392, wifiSent: 1459193, wirelessWanDataReceived: 877855, wirelessWanDataSent: 1585215)
Upload progress in %: 10
2018-07-28 12:46:25.021824+0200 xxxxxxx[273:15018] [] tcp_connection_write_eof_block_invoke Write close callback received error: [89] Operation canceled
2018-07-28 12:46:25.023432+0200 xxxxxxx[273:15018] [] tcp_connection_write_eof_block_invoke Write close callback received error: [89] Operation canceled
DataUsageInfo(wifiReceived: 11090392, wifiSent: 1459193, wirelessWanDataReceived: 877855, wirelessWanDataSent: 1585215)
Upload progress in %: 10
DataUsageInfo(wifiReceived: 11090392, wifiSent: 1459193, wirelessWanDataReceived: 877855, wirelessWanDataSent: 1585215)
Upload progress in %: 10\

So there is a TCP error, but the transfer of the blob is not stopped nor a fault is catched/shown by the completion handler and that leads to not existing files/images on my cloud Blob Storage account!

The completion handler does not show a error message, when the transfer of image was unsuccessful.

//Upload to Azure Blob Storage with help of SAS
func uploadBlobSAS(container: String, sas: String, blockname: String, fromfile: String ){

// If using a SAS token, fill it in here.  If using Shared Key access, comment out the following line.
let containerURL = "https://xxxxxxx.blob.core.windows.net/\(container)\(sas)"  //here we have to append sas string: + sas
    print("containerURL with SAS: \(containerURL) ")
var container : AZSCloudBlobContainer
var error: NSError?
    
container = AZSCloudBlobContainer(url: NSURL(string: containerURL)! as URL, error: &error)
if ((error) != nil) {
print("Error in creating blob container object.  Error code = %ld, error domain = %@, error userinfo = %@", error!.code, error!.domain, error!.userInfo);
}
else {

    let blob = container.blockBlobReference(fromName: blockname)
    blob.uploadFromFile(withPath: fromfile, completionHandler: {(NSError) -> Void in
        
        if (error != nil){
            //!!!!!!! NEVER GETS HERE EVEN IF THE TRANSACTION WAS UNSUCCESSFULL !!!!!!!!!!!
            
        }
        else {
            NSLog("Ok, uploaded !")
            //3. Leave dispatch group
            self.taskGroup.leave()
        }  
    })
    }

}

Have you found a mitigation/solution?

Not a real solution, but a workaround to this bug. I now check every file if it is present on the server after the completion handler shows me that everything was fine...if the files are not there I show now a error message.

[zezha-msft]

Hi @Sub-Zero-1, thanks for reaching out, and I apologize for the inconvenience.

I've logged this issue for investigation.

[Sub-Zero-1]

Hi, I now saw that there is a pull request for "managing lost connection error". Maybe this resolvse the issue!? I can't check here now, cause my mobile connection never reaches Edge connection speed anymore, so the error does not occur on my device anymore. Ill search for a way to slow down connection speed manually on my iPhone by App or so.

[baptadn]

Hi there!
Any update about this issue?

Thanks :)