iOS Question CallSubDelayed

[Moosi]

Hi,

I´m struggling with the concept of (fake)asynchronous tasks. What is the right way to deal with it?

That´s what I´m doing right now (Simplified for testing):

Sub SetText(t As Int)
    Log("SetText: " & t)
    Label1.Text = "Count: " &t
End Sub

Sub Run
    For i=0 To 10
        Log("Run" & i)
        CallSubDelayed2(Me,"SetText", i )
    Next
End Sub

Sub BtnStart_Click
    For i=0 To 100
        Log("Click: " & i)
        CallSubDelayed(Me, "Run")
    Next
End Sub

I read several times from Erel to split up larger tasks to smaler ones and use CallSubDelayed to call them.
I´m as well doing this in the Main Task right now.

The result is right now:
I geht 100 times the Log("Click") and then the Log ("Run").
After all is finished, the Label jumps to "Count: 10" (obviously)

So, what I am doing wrong? In Android I would use DoEvents but that does not exist in iOS. What is the right way to deal with it?

i would be really happy if someone cold point me in the right direction.

Thanks for your help
Andreas
Attached the Test Project.

 

[Erel]

What are you trying to do? Do you want to update the label text every few milliseconds?

There is no task to split here.

 

[Moosi]

Hi Erel,
thanks for your reply.
I want to update the Label accordingly to the progress of the For...Next

In reality I´m parsing a large XML with Sax, but the effect is the same. The Update is never fired until the job is done.

 

[Erel]

The details are important here. You will not be able to split the parsing task.

However, have you tested it in release mode? It can be much faster.

 

[Moosi]

yes I tested in release mode. Same Problem.

I have the same issue with httpUtils2. Downloading many images and I am not getting any progress until the end.

I seems to be all related to the same. While a loop is running, no updates to the GUI are happening.

 

[Erel]

HttpUtils2 downloads everything in the background. It will not affect the UI.

Can you post this XML file?

 

[Moosi]

Sure, this is the file.
Ok, so there is no way of having some sort of progress while parsing and/or downloading?
Is the only option to just show a Spinning Icon for minutes?

 

[Erel]

If you are downloading multiple files then you can show a message that says x out of y files were downloaded.

 

[Moosi]

Ah, ok cool. how do I archive this?

 

[Erel]

You can update the message in JobDone event. Use a global variable to count how many files were downloaded.

 

[Erel]

BTW, I tried to measure the time it takes to parse this XML file. On an iPhone 5s it should take about 200ms (in release mode).

 

[Moosi]

Hmmm, thats exactly what I did.
CallSubDelayed2(Main, "MoveProgressBar", ProgressStep)

Where MoveProgressBar moves the Bar

 

[Moosi]

Thanks Erel,
I think even on an Iphone4 it will be ok, just the parsing.
I wanted to move the progress with every step in the process chain.
Starting with DoSomeSQL, ServerConnet, DownloadXML, ParseXML, DownloadFiles...

I think that the UserExperience is better if something happens, rather than seeing a blank screen.

 

[Erel]

Downloading files and server connections do not affect the UI. They happen in the background.

There will soon be support for asynchronous SQL commands as well.

The parsing is fast enough to be ignored.

 

[Moosi]

Many Thanks,
asynchronous SQL would be wonderful...
right now I am testing if it is better to call the Label/Progress directly from the JobDone or use a CallSubDelayed.

The next step will be to test if there are problems with downloading 500+ Files via httpUtils2.
Are there known issues? With B4A ist´s working verry good....

 

[Erel]

Asynchronous SQL commands are now supported.

It will be faster to zip the 500 files and download them as a single package. There aren't any known issues related to the number of concurrent downloads.

 

[Moosi]

Asynchronous SQL commands are now supported.

perfect, thanks for your effort.

It´s working pretty fast with 500 Files.
As the Files are dynamicaly generated it would be more load on serverside to generate all and zip them.
I think I´m pretty happy with the solution for now.