I tested Xcode 7 with but my cocos2d 2.1 games crash on simulator or on devices:
ccShader_PositionColorLenghtTexture_frag.h
2015-06-15 22:36:13.319 NanoWar[18789:456971] cocos2d: ERROR: 0:12: '' : syntax error: #extension must always be before any non-preprocessor tokens
and
cocos2d: ERROR: 0:26: Invalid call of undeclared identifier 'fwidth'
This class crash the game
#extension GL_OES_standard_derivatives : enable
#ifdef GL_ES
varying mediump vec4 v_color;
varying mediump vec2 v_texcoord;
#else
varying vec4 v_color;
varying vec2 v_texcoord;
#endif
void main()
{
#ifdef GL_OES_standard_derivatives
#if defined GL_OES_standard_derivatives
gl_FragColor = v_color*smoothstep(0.0, length(fwidth(v_texcoord)), 1.0 - length(v_texcoord));
#else
gl_FragColor = v_color*step(0.0, 1.0 - length(v_texcoord));
#endif
#endif
}