title: How to concatenate char and string on iPhone?
body: <p>I want to add some marks to separate some strings. 
  How to add a char to a string?</p>
  
  <p>e.g. add '\x01' to "Hello", add '\x02' before "World" and add '\x03' after "World".</p>
  
  <p>So I can create a string "\x01 Hello \x02 World \x03" which has some separate marks.</p>