title: Calculate the range of visible text in UILabel
body: <p>I have an <code>UILabel</code> with fixed size, the text that I set into this <code>UILabel</code> can be 200, 5 or 500 characters long. What I want to do is to calculate how much visible text can I put into this <code>UILabel</code> with the current <code>UILabel</code> size.</p>
  
  <p>Why I want to do that? Because I want to add a <code>...Read more</code> text at the end of the text, but not at the end of the whole text, just at the end of the visible text in the <code>UILabel</code>.</p>
  
  <p>Thanks in advance.</p>