title: How to add/subtract time in swift
body: <p>To get the current date and time im using the below code: </p>
  
  <pre><code>var currentTime = getFormatedDateTime(dateTime: Date()) 
  </code></pre>
  
  <p>i have to check if the current date and time is same as the selected timezone.
  To get the Eastern Standard Time i'm using this code:</p>
  
  <pre><code>    TimeZone.ReferenceType.default = TimeZone(abbreviation: "EST")!
      let formatter = DateFormatter()
      formatter.timeZone = TimeZone.ReferenceType.default
      formatter.dateFormat = "yyyy-MM-dd hh:mm a"
      let strDate = formatter.string(from: Date())
      print("time : \(strDate)")
  </code></pre>
  
  <p>Can you help me to add/subtract time from the current time to the timezone?</p>