title: maximum/minimum on incrementing buttons
body: <p>I'm fairly new to Xcode/Swift and am wondering how to set a maximum and minimum for amounts that result in a plus and minus button being touched. My existing code is below. The notifyBeforeAvailabilty I want to go from 1-20 and the ratePerMinute I want to go from $0.00 to $15.00.</p>
  
  <pre><code>var notifyBeforeAvailability: Int!
  var ratePerMin: Float!
  
  
  notifyBeforeAvailability = 1
  updateNotifyBeforeAvailability()
  ratePerMin = 0.10
  updateRatePerMin()
  
  
   @IBAction func notifyBeforeAvailabilityPlus(sender: AnyObject) {
      notifyBeforeAvailability = notifyBeforeAvailability + 1
      updateNotifyBeforeAvailability()
  }
  @IBAction func notifyBeforeAvailabilityMinus(sender: AnyObject) {
      notifyBeforeAvailability = notifyBeforeAvailability - 1
      updateNotifyBeforeAvailability()
  }
  func updateNotifyBeforeAvailability() {
      lblNotifyTime.text = String(notifyBeforeAvailability) + "min"
  }
  
  
  @IBAction func ratePerMinPlus(sender: AnyObject) {
      ratePerMin = ratePerMin + 0.10
      updateRatePerMin()
  }    
  @IBAction func ratePerMinMinus(sender: AnyObject) {
      ratePerMin = ratePerMin - 0.10
      updateRatePerMin()
  }
  func updateRatePerMin() {
      let currentValue = ratePerMin
      let current_string = String.localizedStringWithFormat("%.2f", currentValue)
      lblYourRate.text = "$" + current_string
  }
  </code></pre>