title: How to get first four letters from string in Swift 3?
body: <p>I am trying to do IFSCCode validation in swift, but the problem I'm facing is I am not able to fetch the first four letters in string.</p>
  
  <p>IFSC Code example:</p>
  
  <blockquote>
    <p>ABCD0200000</p>
  </blockquote>
  
  <p>This is how an IFSC Code looks:</p>
  
  <ol>
  <li>First four characters in IFSC Code are always alphabets</li>
  <li>Fifth character is always a zero.</li>
  <li>And rest can be anything</li>
  <li>The length of IFSC Code should not be greater than or less than 11. It should 11 in length.</li>
  </ol>
  
  <p>I have written code for ifs code validation in Objective C, but I am not that familiar in Swift so getting a problem in replicating the same in Swift.</p>
  
  <p>The following is the code which I have written in Objective C:</p>
  
  <pre><code>- (BOOL)validateIFSCCode:(NSString*)ifsccode {
    if (ifsccode.length &lt; 4) {
      return FALSE;
    }
    for (int i = 0; i &lt; 4; i++) {
      if (![[NSCharacterSet letterCharacterSet]
              characterIsMember:[ifsccode characterAtIndex:i]]) {
        return FALSE;
      }
    }
    if (ifsccode.length &lt; 10) {
      return FALSE;
    }
    if ([ifsccode characterAtIndex:4] != '0') {
      return FALSE;
    } else {
      return TRUE;
    }
  }
  </code></pre>
  
  <p>In Swift 3</p>
  
  <pre><code>func validateIfscCode(_ ifscCode : String) -&gt; Bool{
      if(ifscCode.characters.count &lt; 4){
          return false;
      }
  
      for( _ in 0 ..&lt; 4){
          let charEntered = (ifscCode as NSString).character(at: i)
      }
      if(ifscCode.characters.count &lt; 10){
          return false;
      }
  
      let idx = ifscCode[ifscCode.index(ifscCode.startIndex, offsetBy: 4)]
  
      print("idx:%d",idx)
      if (idx == "0"){
      }
      return true
  }
  </code></pre>