Date formatters, lazily instantiated once
This isn't the way to compare two dates...it violates one of my commandments.  We can &amp; should use NSCalendar's compareDate method:

extension NSDate {
    func isSameDayAs(date: NSDate) -&gt; Bool {
        let calendar = NSCalendar.currentCalendar()
        let dif = calendar.compareDate(self, toDate: date, toUnitGranularity: .DayCalendarUnit)
        return dif = .OrderedSame
    }
}




Moreover, your date formatter methods don't have any business in the view controller.  These make more sense also as NSDate extension methods.  However, creating NSDateFormatters is actually a pretty expensive operation.  We don't want to do it more often than necessary.  So, let's make a struct to handle one formatter per style we want:

extension NSDate {
    private struct Formatters {
        static let timeFormatter = { (Void) -&gt; NSDateFormatter in
            let formatter = NSDateFormatter()
            formatter.dateFormat = "hh:mm"
            return formatter
        }()

        static let yearMonthDayFormatter = { (Void) -&gt; NSDateFormatter in
            let formatter = NSDateFormatter()
            formatter.dateFormat = "yyyy/MM/dd"
            return formatter
        }()
    }

    var timeString: String {
        get {
            return Formatters.timeFormatter.stringFromDate(self)
        }
    }

    var yearMonthDayString: String {
        get {
            return Formatters.yearMonthDayFormatter.stringFromDate(self)
        }
    }
}


Importantly, using this approach makes unit testing (which you should definitely be doing) quite easy.  And, we've put code in places where it makes sense.