title: how to change background color of seizer path
body: <p>I have unbutton  as below,</p>
  
  <pre><code>    taskBtn=[[PNTButton alloc]initWithFrame:CGRectMake(0,0,app.screenwidth,app.screenheight/2)];
      [taskBtn setBackgroundColor:[UIColor clearColor]];
      [taskBtn addTarget:self action:@selector(taskBtnClicked:) forControlEvents:UIControlEventTouchUpInside];
      [self.view addSubview:taskBtn];
  </code></pre>
  
  <p>i have drawn a triangle using beizerpath on task button ,when user clicks on triangle i need to change  change the background color of triangle but i was unable to change background color.its giving error as:</p>
  
  <p><code>CGContextSetFillColorWithColor</code>: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.</p>
  
  <p>can anyone help me how to change background color of beizerpath triangle when user clicks on it.</p>