title: how can I add one minutes in current NSDate of iphone and save in NSDate?
body: <p>I can get current date of iphone via this code as </p>
  
  <pre><code>NSDate *currentDate = [NSDate date];
  NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
  [dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm"];
  
  NSString *dateString = [dateFormatter1 stringFromDate:currentDate];
  </code></pre>
  
  <p>Now I just want to increase one mint then save NSString format,
  how can I?</p>