[swift4] NSdateとStringの相互変換関数

NSdateとStringの相互変換関数を記述しておく

class DateUtils {
    class func dateFromString(string: String, format: String) -> NSDate {
        let formatter: DateFormatter = DateFormatter()
        _ = Calendar(identifier: .gregorian) // グレゴリオ歴
        formatter.dateFormat = format
        return formatter.date(from: string)! as NSDate
    }
    
    class func stringFromDate(date: NSDate, format: String) -> String {
        let formatter: DateFormatter = DateFormatter()
        _ = Calendar(identifier: .gregorian) // グレゴリオ歴
        formatter.dateFormat = format
        return formatter.string(from: date as Date)
    }
}

使い方

let date = DateUtils.dateFromString(string: "2018-12-25 12:00:00", format: "yyyy-MM-dd HH:mm:ss")

let srt = DateUtils.stringFromDate(date, format: "yyyy-MM-dd HH:mm:ss"))