What is the preferable way of getting a dynamic length string from memory (which is also compatible with XE and XE7 - the two IDEs I use)?

What is the preferable way of getting a dynamic length string from memory (which is also compatible with XE and XE7 - the two IDEs I use)?

I have found:

function AMethod(nBuffer : Integer) : string;
var
  buffer: array of Char;
  nBuffer: Cardinal;
begin
  SetLength(buffer, nBuffer);
  GetAStringFromSomewhere(PChar(buffer), nBuffer);
  Result := StrPas(PChar(buffer));
end;

and

function AMethod(nBuffer : Integer) : string;
var
  buffer: array of Char;
  nBuffer: Cardinal;
begin
  SetLength(buffer, nBuffer);
  GetAStringFromSomewhere(PChar(buffer), nBuffer);
  SetString(Result, PChar(buffer), nBuffer (??   should be a length));  // Something like this
end;

There is another one which I can't think of (which takes a TArray - I think)...

Any others?