title: how do i let text fit to UIButton?
body: <h2>problem:</h2>
  
  <p>Button size is enough, however when I change title, the title text cannot fit the button width. Any SDK function can solve this problem, or I need to manually code to solve it?</p>
  
  <p>Please refer to following pictures.</p>
  
  <p>design in the nib file. 
  <img src="https://i.stack.imgur.com/May9F.png" alt="enter image description here"></p>
  
  <p>initial show in simulator
  <img src="https://i.stack.imgur.com/2r4Zr.png" alt="enter image description here"></p>
  
  <p>when I change the title text
  <img src="https://i.stack.imgur.com/Zeakm.png" alt="enter image description here"></p>
  
  <h2>tried some ways before</h2>
  
  <ol>
  <li><p>_button.titleLabel.adjustsFontSizeToFitWidth = YES;<br>
  the way will change my font size. I cannot accept the way.</p></li>
  <li><p>[_button setTitleEdgeInsets:UIEdgeInsetsMake(10.0, 10.0, 0.0,0.0)];  <br>
  the way change label's position only, not label size.</p></li>
  <li><p>[_button.titleLabel sizeToFit];<br>
  result is same with picture(3).</p></li>
  <li><p>[_button sizeToFit]; <br>
  title moved to upper left corner, and the title still the same result.</p></li>
  </ol>
  
  <p>Just confused, my button size is big enough, why title size is so small?</p>