TCP-Client for iOS

Elements Oxygene
1

Hello,
I’m new to Oxygen and was introduced by Jens. He tought me a lot about the commonly used construct of a project written in this language. But first and foremost he brought me back from Delphi XE6 on the right track.

Now I have to write a small TCP-Client for iOS. I found the following code in Objective-C:
How to open a TCP socket in Objective-C
Then I translated the code to Oxygen, so it looks like this Client.pas (3.2 KB)
If I try to send some data to my server (written in D7) I will notice a connection but no data will be received.
The server hangs up at “Server.Socket.ReadLn;”

The problem may be the following part:

method ServerConnector.writeOut(s: NSString);
begin
  var buf:= Byte(s.UTF8String); // originally: uint8_t *buf = (uint8_t *)[s UTF8String];
  fOutputStream.&write(@buf) maxLength(Char(buf).stringValue.length); // originally: [outputStream write:buf maxLength:strlen((char *)buf)];

end;

I think I have done some mistakes while translating.

I would be glad if you could help me.

Best regards
Benny

2

whats wrong with just strlen(buf) for the last parameter?

You’re casting the pointer to a char, calling stringValue on that (which gives you a new NSString of just that one Char ± not actually even the first char of the string, but the poiter, reinterpreted as Char), and then calling length (which gives you back “1”)

3

strlen expects a ^AnsiChar and If I try to cast this

OutputStream.&write(@buf) maxLength(strlen(^AnsiChar(buf)));

I ll get a BAD_ACCESS exception

4

Come to think, there’s more wrong with this. s.UTF8String returns a char pointer (think pChar), but you cast it to a byte. not to a byte pointer, to a plain byte. That’s all but the lowest 8 bits gone, right there.

Then you pass the address of that byte to write() maxLength(). There’s at most 1 valid byte to find at that address (the lowest 8 bits truncated from the original char’s address.

You’ll want something like:

var buf:= s.UTF8String; // no cast, this will be an ^AnsiChar
fOutputStream.&write(buf) maxLength(strlen(but))

ad if that deposit like passing an AnsiChar^ to write() maxLength(), you might need to add a case to ^Bute, such as

fOutputStream.&write(^Byte(buf)) maxLength(strlen(but))

But what you can’t to is just cast from poster types to simply types, and back.

Hope this helps,
marc

1 Like
5

Now I understand. Thank you for that!
But the server still hangs up at

Server.Socket.ReadLn;

It seems that the stream didn’t get flush. But also after closing the app (from the dock) my server doesn’t receive any data.

6

I’d probably need to see more to comment on that new part.

7

Here is the whole class:

interface

uses UIKit;

type
  Communicator = public class(INSStreamDelegate) 
  private
    fReadStream: CFReadStreamRef;
    fWriteStream: CFWriteStreamRef;
    fInputStream: NSInputStream;
    fOutputStream: NSOutputStream;

    method setup;
    method open;
    method close;
    method stream(stream: NSStream) handleEvent(&event: NSStreamEvent);
    method readIn(s: NSString);
    method writeOut(s: NSString);
  public
    constructor; 
  end;

implementation

constructor Communicator;
begin
  setup;
  writeOut('Test\n');
end;

method Communicator.setup;
begin
  CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, 'xx.xxx.xxx.xxx', 8080, @fReadStream, @fWriteStream);
  if not CFWriteStreamOpen(fWriteStream) then
  begin
    NSLog('Error, WriteStream not open');
    exit;
  end;
  self.open();
  NSLog('Status of OutputStream: %i', fOutputStream.streamStatus());
  exit;
end;

method Communicator.open;
begin
  NSLog('Opening streams.');
  fInputStream := bridge<NSInputStream>(fReadStream);
  fOutputStream := bridge<NSOutputStream>(fWriteStream);

  fInputStream.setDelegate(self);
  fOutputStream.setDelegate(self);
  fInputStream.scheduleInRunLoop(NSRunLoop.currentRunLoop()) forMode(NSDefaultRunLoopMode);
  fOutputStream.scheduleInRunLoop(NSRunLoop.currentRunLoop()) forMode(NSDefaultRunLoopMode);
  fInputStream.open();
  fOutputStream.open();
end;

method Communicator.close;
begin
  NSLog('Closing streams.');
  fInputStream.close();
  fOutputStream.close();
  fInputStream.removeFromRunLoop(NSRunLoop.currentRunLoop()) forMode(NSDefaultRunLoopMode);
  fOutputStream.removeFromRunLoop(NSRunLoop.currentRunLoop()) forMode(NSDefaultRunLoopMode);
  fInputStream.setDelegate(nil);
  fOutputStream.setDelegate(nil);

  fInputStream := nil;
  fOutputStream := nil;
end;

method Communicator.stream(stream: NSStream) handleEvent(&event: NSStreamEvent);
begin
  NSLog('Stream triggered.');
  case &event of
    NSStreamEvent.NSStreamEventHasSpaceAvailable: begin
      if stream = fOutputStream then
      begin
        NSLog('OutputStream is ready.');
      end;
    end;
    NSStreamEvent.NSStreamEventHasBytesAvailable: begin
      if stream = fInputStream then
      begin
        NSLog('InputStream is ready.');
        var buf: array[1024] of uint8_t;
        var len: Integer := 0;
        len := fInputStream.&read(buf) maxLength(1024);
        if len > 0 then
        begin
          var data: NSMutableData := NSMutableData.alloc().initWithLength(0);
          data.appendBytes(@buf) length(len); // originally:     [data appendBytes: (const void *)buf length:len];
          var s: NSString := NSString.alloc().initWithData(data) encoding(NSStringEncoding.NSASCIIStringEncoding);
          self.readIn(s);          
        end;
      end;
    end;
    else begin
      NSLog('Stream is sending an Event: %i', &event);
    end;
  end;
end;

method Communicator.readIn(s: NSString);
begin
  NSLog('Reading in the following:');
  NSLog('%@', s);
end;

method Communicator.writeOut(s: NSString);
begin
  var buf:= s.UTF8String();
  fOutputStream.&write(^Byte(buf)) maxLength(strlen(buf));
  
  NSLog('Writing out the following:');
  NSLog('%@', s);
end;

end.

My server uses the TIdTCPServer (Indy 10) and has the following method:

procedure TServerEventHandler.OnServerExecute(AContext: TIdContext);
var StreamSize: Int64;
    Cmd: String;
    Response: TMemoryStream;
    RequestHandler: TRequestHandler;
begin     
 Cmd:= Trim(AContext.Connection.IOHandler.ReadLn);
 WriteLn(Format('[%s, %s] Requested: [%s]',            // doesn't get reached
                 [DateTimeToStr(now),
                  AContext.Connection.Socket.Binding.IP,
                  Cmd]));
 Response:= TMemoryStream.Create;
 RequestHandler:= TRequestHandler.Create(Response);    
 try
  RequestHandler.GetResponse(Cmd);
  Response.Seek(0, soFromBeginning);
  StreamSize:= Response.Size;
  AContext.Connection.IOHandler.Write(StreamSize);
  AContext.Connection.IOHandler.Write(Response);
  AContext.Connection.DisconnectNotifyPeer;
 finally
  RequestHandler.Free;
  Response.Free;
 end;
end;