Displaying chinese characters in OF 0.11?

I’m trying to display chinese characters using ofTrueTypeFont. I am using a font that supports chinese character and the .cpp file is saved as utf but nothing shows when I try to write some chinese unless I load the text from a file?

//--------------------------------------------------------------
void ofApp::setup()
{
	ofTrueTypeFontSettings settings("chinese.msyh.ttf", 24);
	settings.antialiased = true;
	settings.dpi = 72;
	//settings.direction = OF_TTF_LEFT_TO_RIGHT;
	settings.addRanges(ofAlphabet::Chinese);
	settings.addRanges(ofAlphabet::Latin);
	settings.addRange(ofUnicode::CJKUnified);

	if (!font.load(settings))
		cout << "couldn't load font" << endl;

	auto bufferLines = ofBufferFromFile("intro.txt").getText();
	for (int i = 0; i < bufferLines.size(); i++) {
		str += bufferLines[i];
	}
}

//--------------------------------------------------------------
void ofApp::draw()
{
	ofBackground(0, 255, 0);

	string t = "你好";

	ofSetColor(255, 255, 255);
	font.drawString(t, 20, 50);
	ofSetColor(255, 0, 255);
	font.drawString(str, 20, 70);
}