How to turn a NSDate into readable Date (Singleton)

Question

I'm using an extension to NSDate:

extension NSDate {
    func toDayMonthYear() -> String {
        let formatter = NSDateFormatter()
        formatter.dateFormat = "dd.MM.yy"
        return formatter.stringFromDate(self)
    }
}

This way I can easily turn any values to NSDate

print(NSDate().toDayMonthYear)   => "12.11.2015"

But I understand that each and every time this gets called, an instance of NSDateFormatter is created which is - performancewise - catastrofic...

How can I do that more elegantly?

how often is called toDayMonthYear() ? For usual usage it seems fine — nsinvocation, Nov 12 '15 at 20:46
See http://stackoverflow.com/questions/28504589/whats-the-best-practice-for-nsdateformatter-in-swift. — Martin R, Nov 12 '15 at 20:47
It is used very often. That's why I'm worried about performance. And it's not quite as easy as Martin R says, because I'm within an extension. I want this independantly from any other classes. — Timm Kent, Nov 12 '15 at 20:49

Martin R · Accepted Answer · 2015-11-12T21:07:11.870

You can define a static property (which is assigned only once) locally in functions or (extension) methods, but you need to embed it in a structure:

extension NSDate {

    func toDayMonthYear() -> String {

        struct Statics {
            static var formatter : NSDateFormatter = {
                let fmt = NSDateFormatter()
                fmt.dateFormat = "dd.MM.yy"
                return fmt
            }()
        }

        return Statics.formatter.stringFromDate(self)
    }
}

How to turn a NSDate into readable Date (Singleton)

1 Answers1