title: error appears when I type on UITextfield with physical keyboard in iOS7
body: <p>Recently I upgrade my Xcode to Xcode5...</p>
  
  <p>Sometimes running my app on my iPhone/iPad Simulator when I try to write on any UITextfield of my app (with my physical keyboard) this error appears on my Xcode5 ouptut window:</p>
  
  <pre><code>&lt;Error&gt;: CGContextSetBlendMode: 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.
  </code></pre>
  
  <p>if I use the keyboard of the simulator (screen), it works fine, but for testing purposes I'd rather typing on my Mac's Keyboard for quick development/testing, any ideas how to fix this???</p>
  
  <p>thanks in advance</p>