[objc/swift] unix 와 같은 13자리 timestamp 얻기

objc:

long long milliseconds = (long long)([[NSDate date] timeIntervalSince1970] * 1000.0);

swift:

// ex1)
let currentDate = NSNumber(value:Int64(Date().timeIntervalSince1970 * 1000))

// ex2)
extension Date {
    
    func toMillis() -> NSNumber {
        return NSNumber(value:Int64(timeIntervalSince1970 * 1000))
    }
    
    var timestamp: Int64 {
        Int64(timeIntervalSince1970 * 1000)
    }
}