Issues with localising greeting message

I am just finishing up my first app and have been localising different features. I have one feature in my app that I am not sure if I can localise or not.

Basically, when users open my app, they are greeted with a message that says 'good afternoon', 'good morning' or 'good evening'. I created some code that checks the prefix of the time to decide what message to display, however since different countries format time differently, I'm not sure how I can localise this.

Will I have to figure out the countries that it does work in and add an if statement that decides whether the app can display this greeting or not? Otherwise display a greeting based on their name instead?

Here is my code:

var date = NSDate()
    let dateFormatter = NSDateFormatter()
    dateFormatter.timeStyle = .ShortStyle
    let time = dateFormatter.stringFromDate(date)

    var currentTimeOfDay = ""

    if time.hasPrefix("0") {
        currentTimeOfDay = "morning"
    } else if time.hasPrefix("10") {
        currentTimeOfDay = "morning"
    } else if time.hasPrefix("11") {
        currentTimeOfDay = "morning"
    } else if time.hasPrefix("12") {
        currentTimeOfDay = "morning"
    } else if time.hasPrefix("13") {
        currentTimeOfDay = "afternoon"
    } else if time.hasPrefix("14") {
        currentTimeOfDay = "afternoon"
    } else if time.hasPrefix("15") {
        currentTimeOfDay = "afternoon"
    } else if time.hasPrefix("16") {
        currentTimeOfDay = "afternoon"
    } else if time.hasPrefix("17") {
        currentTimeOfDay = "afternoon"
    } else if time.hasPrefix("18") {
        currentTimeOfDay = "evening"
    } else if time.hasPrefix("19") {
        currentTimeOfDay = "evening"
    } else if time.hasPrefix("2") {
        currentTimeOfDay = "evening"
    }

Solution

You should not use a localized time string to determine the time of the day.

Use NSCalendar and NSDateComponents:

let now = NSDate()
let cal = NSCalendar.currentCalendar()
let comps = cal.components(.CalendarUnitHour, fromDate: now)
let hour = comps.hour

Now hour is an integer in the range 0 ... 23.

var currentTimeOfDay = ""
switch hour {
case 0 ... 12:
    currentTimeOfDay = "morning"
case 13 ... 17:
    currentTimeOfDay = "afternoon"
default:
    currentTimeOfDay = "evening"
}