title: Twitter API issues.“Authentication needed”"Failed to validate oauth signature and token"
body: <p>Friends,I got a question,and I have googled it,but I didn't find the answer.</p>
  
  <p>I create an iOS twitter app,and apply for a twitter API.
  I used my API key in my app,Xcode returns error.
  Just like this: <a href="http://tinypic.com/r/262ksnk/8" rel="nofollow">http://tinypic.com/r/262ksnk/8</a><br>
  ("Failed to validate oauth signature and token")</p>
  
  <p>and this picture is my twitter api status
  (sorry,I do not have enough coin to upload a pic,so post my pic <a href="http://tinypic.com/r/ifd8jq/8" rel="nofollow">here</a>. )</p>
  
  <p>what is wrong with my twitter api,can anyone help me?</p>
  
  <p>Thanks very much.</p>
  
  <p>What is wrong?</p>
  
  <p>Best regards.</p>