c++ - Failed to compile vertex shader OpenGL iOS -

i trying use opengl first time , i've ran error can not figure out.

i using code:

here vertex shader code:

attribute vec4 position; //attribute mediump vec4 inputtexturecoordinate; // //varying mediump vec2 texturecoordinate;  attribute vec4 inputtexturecoordinate;  varying vec2 texturecoordinate;  void main() {     gl_position = position;     texturecoordinate = inputtexturecoordinate.xy; } 

and here code trying load with

nsstring *vertshaderpathname, *fragshaderpathname;  // create shader program. *programpointer = glcreateprogram();  // create , compile vertex shader. vertshaderpathname = [[nsbundle mainbundle] pathforresource:vertexshadername oftype:@"vsh"]; if (![self compileshader:&vertexshader type:gl_vertex_shader file:vertshaderpathname]) {     nslog(@"failed compile vertex shader"); 

and error of failed compile vertex shader , crashes application. know how can fix issue?