title: Get a substring from an NSString until arriving to a specific word
body: <p>Let us say I have this <code>NSString</code>: <code>@"Country Address Tel:number"</code>.
  How can I do to get the substring that is before <code>Tel</code>? (Country Address )
  And then How can I do to get the substring that is after <code>Tel</code>? (number)</p>