when i using design a titled map with 1280 * 1920 and put it into cocostudio the convas size set 960* 640.
in cpp appdelegate i set designresoutionsize 960*640
if i do not sacle CCTMXLayer.cpp with  _contentScaleFactor the map will show in 480 * 320 in screen, and in this case value of _contentScaleFactor is 4,
you can run testcase cocos2dxv3.0rc0  to check titled map on different device simulator, you will find the map scale will different.