It breaks on line 61

EDCubeDemoViewController.m

- (BOOL)loadShaders
{
    GLuint vertShader, fragShader;
    NSString *vertShaderPathname, *fragShaderPathname;
    
    // Create shader program.
    program = glCreateProgram();
    
    // Create and compile vertex shader.
    vertShaderPathname = [[NSBundle mainBundle] pathForResource:@"Shader" ofType:@"vsh"];
    if (![self compileShader:&vertShader type:GL_VERTEX_SHADER file:vertShaderPathname])
    {
        NSLog(@"Failed to compile vertex shader");
        return FALSE;
    }
    
    // Create and compile fragment shader.
    fragShaderPathname = [[NSBundle mainBundle] pathForResource:@"Shader" ofType:@"fsh"];
    if (![self compileShader:&fragShader type:GL_FRAGMENT_SHADER file:fragShaderPathname])
    {
        NSLog(@"Failed to compile fragment shader");
        return FALSE;
    }
    
    // Attach vertex shader to program.
    glAttachShader(program, vertShader);
    
    // Attach fragment shader to program.
    glAttachShader(program, fragShader);
    
    // Bind attribute locations.
    // This needs to be done prior to linking.
    glBindAttribLocation(program, ATTRIB_VERTEX, "position");
    glBindAttribLocation(program, ATTRIB_TEXTURE_COORD, "texture_coord");
    
    // Link program.
    if (![self linkProgram:program])
    {
        NSLog(@"Failed to link program: %d", program);
        
        if (vertShader)
        {
            glDeleteShader(vertShader);
            vertShader = 0;
        }
        if (fragShader)
        {
            glDeleteShader(fragShader);
            fragShader = 0;
        }
        if (program)
        {
            glDeleteProgram(program);
            program = 0;
        }
        
        return FALSE;
    }
    
    // Get uniform locations.
    uniforms[UNIFORM_MVP_MATRIX] = glGetUniformLocation(program, "mvp_matrix");
    uniforms[UNIFORM_TEXTURE] = glGetUniformLocation(program, "texture");
    
    // Release vertex and fragment shaders.
    if (vertShader)
        glDeleteShader(vertShader);
    if (fragShader)
        glDeleteShader(fragShader);
    
    return TRUE;
}

- (BOOL)compileShader:(GLuint *)shader type:(GLenum)type file:(NSString *)file
{
    GLint status;
    const GLchar *source;
    
    source = (GLchar *)[[NSString stringWithContentsOfFile:file encoding:NSUTF8StringEncoding error:nil] UTF8String];
    if (!source)
    {
        NSLog(@"Failed to load vertex shader");
        return FALSE;
    }
    
    *shader = glCreateShader(type);
    glShaderSource(*shader, 1, &source, NULL);
    glCompileShader(*shader);
        
    glGetShaderiv(*shader, GL_COMPILE_STATUS, &status);
    if (status == 0)
    {
        glDeleteShader(*shader);
        return FALSE;
    }
    
    return TRUE;
}

Shader.fsh

varying highp vec2 texCoordVarying;

uniform sampler2D texture;

void main()
{
    gl_FragColor = texture2D(texture, texCoordVarying);
    gl_FragColor.a = 0.85;

}

Shader.vsh

attribute vec4 position;
attribute vec4 texture_coord;

varying vec2 texCoordVarying;

uniform mat4 mvp_matrix;

void main()
{
    gl_Position = mvp_matrix * position;
    
    texCoordVarying = texture_coord.st;
}