I can get the 24 hour style time, but how do I get the 12 hour format with the am and pm?
let date = NSDate()
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Hour, .Minute, .Second], fromDate: date)
let hour = components.hour
let minutes = components.minute
As you say, you should use NSDateFormatter for your desired format. Hope this will help you.
let date = NSDate()
let formatter = NSDateFormatter()
formatter.dateFormat = "hh:mm a"
let time = formatter.stringFromDate(date)
For more information about date formatter see NSDateFormatter
Swift 3.1 Answer
let date = Date() //Jun 1, 2017, 10:22 AM"
let formatter = DateFormatter() //<NSDateFormatter: 0x608000244380>
formatter.dateFormat = "hh:mm a" //<NSDateFormatter: 0x608000244380>
let time = formatter.string(from: date) //"10:22 AM"
Time format must be in 'hh' not HH
formatter.dateFormat = "hh:mm a"
let str=dict["startDateTime"] as! String //if the date is in the array
let str="16:00" //if you want to use static date
let index=str.index(str.startIndex, offsetBy: 11)
let end_index=str.index(str.endIndex, offsetBy:-3)
let dateAsString = str[index ..< end_index]
let dateFormatter=DateFormatter()
dateFormatter.dateFormat="HH:mm"
let date = dateFormatter.date(from: String(dateAsString))
dateFormatter.dateFormat = "h:mm a"
let Date12 = dateFormatter.string(from: date!)
print(Date12)
来源：https://stackoverflow.com/questions/36096533/how-can-i-convert-the-24-hour-time-format-to-12-hour-time-format