DelphiForge: November 2011

I've programmed a small application for iOS using the XE2 and FMX capabilities.
Anyhow, when reaching the stage where I needed to save the data, I've encountered a problem of a foreign language with the FPC.

While using the XE2 strictly with the win32/64 environments there is no such problem of encoding cause of the unicode abilities of the development tool.

However, while porting that to the iOS there need to be a consideration of the FPC limits so far. I've been using the TWideStrings object which does the unicode properly.

There is a sample code writing text to the iOS device on embarcaderos site -- but that didn't help me much due to the use of the foreign language that the application was attended to. When saving the data to the iOS device, I needed to write additional code that writes the data without any consideration of its language - in a binary style if one can.

The following code is to save/load TStream on an iOS device using the FPC, that I have written:

{$IFDEF FPC}
function MyDirectory : NSString;
var
  paths : NSArray;
  fileName : NSString;
begin
  paths := NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, True);
  fileName := paths.objectAtIndex(0);
  Result := fileName;
end;
{$ENDIF}

procedure TForm4.StringListSave(Strings: TWideStrings; FileName: String);
{$IFDEF FPC}
var
  myPath: NSString;
  FNSFileHandle :NSFileHandle;
  data: NSData;
  Mem: TMemoryStream;
{$ENDIF}
begin
{$IFDEF MSWINDOWS}
  Strings.SaveToFile(FileName, TEncoding.UTF8);
{$ENDIF}
{$IFDEF FPC}
  Mem := TMemoryStream.Create;
  Strings.SaveToStream(Mem);
  Mem.Seek(0, TSeekOrigin.soBeginning);
  
  myPath := MyDirectory.stringByAppendingPathComponent(NSSTR(PChar(FileName)));
  NSFileManager.defaultManager.createFileAtPath_contents_attributes(myPath, nil, nil);
  FNSFileHandle := NSFileHandle.fileHandleForWritingAtPath(myPath);
  data  := NSData.dataWithBytes_length(Mem.Memory, NSUInteger(Mem.Size));
  FNSFileHandle.writeData(data);
  FNSFileHandle.closeFile;

Mem.Destroy;
{$ENDIF}
end;

procedure StringListLoad(Strings: TWideStrings; FileName: String);
{$IFDEF FPC}
var
  myPath: NSString;
  //defaultManager: NSFileManager;
  data: NSData;
  FNSFileHandle: NSFileHandle;
  Mem: TMemoryStream;
{$ENDIF}
begin
{$IFDEF MSWINDOWS}
  if FileExists(FileName) then
    Strings.LoadFromFile(FileName)
  else
    Strings.Clear;
{$ENDIF}
{$IFDEF FPC}
  Mem := TMemoryStream.Create;

myPath := MyDirectory.stringByAppendingPathComponent(NSSTR(PChar(FileName)));
  if NSFileManager.defaultManager.fileExistsAtPath(myPath) then
  begin
    FNSFileHandle := NSFileHandle.fileHandleForReadingAtPath(myPath);
    data  := FNSFileHandle.readDataToEndOfFile;
    Mem.SetSize(data.length);
    data.getBytes_length(Mem.Memory, data.length);
    FNSFileHandle.closeFile;

Mem.Seek(0, TSeekOrigin.soBeginning);
    Strings.LoadFromStream(Mem);
  end else
    Strings.Clear;

Mem.Destroy;
{$ENDIF}
end;

DelphiForge

Friday, November 25, 2011

Saving/Loading TStream on iOS device using FPC