这基本上和@TristanLorach发布的答案是一样的，只是为Swift 3重新编码:

   /// Method to get Unix-style time (Java variant), i.e., time since 1970 in milliseconds. This 
   /// copied from here: http://stackoverflow.com/a/24655601/253938 and here:
   /// http://stackoverflow.com/a/7885923/253938
   /// (This should give good performance according to this: 
   ///  http://stackoverflow.com/a/12020300/253938 )
   ///
   /// Note that it is possible that multiple calls to this method and computing the difference may 
   /// occasionally give problematic results, like an apparently negative interval or a major jump 
   /// forward in time. This is because system time occasionally gets updated due to synchronization 
   /// with a time source on the network (maybe "leap second"), or user setting the clock.
   public static func currentTimeMillis() -> Int64 {
      var darwinTime : timeval = timeval(tv_sec: 0, tv_usec: 0)
      gettimeofday(&darwinTime, nil)
      return (Int64(darwinTime.tv_sec) * 1000) + Int64(darwinTime.tv_usec / 1000)
   }

// Timestamp after converting to milliseconds.

NSString * timeInMS = [NSString stringWithFormat:@"%lld", [@(floor([date timeIntervalSince1970] * 1000)) longLongValue]];

获取当前日期的毫秒数。

斯威夫特4 +:

func currentTimeInMilliSeconds()-> Int
    {
        let currentDate = Date()
        let since1970 = currentDate.timeIntervalSince1970
        return Int(since1970 * 1000)
    }

我需要一个NSNumber对象，包含[[NSDate date] timeIntervalSince1970]的确切结果。因为这个函数被调用了很多次，我并不真的需要创建一个NSDate对象，性能不是很好。

所以要得到原始函数给我的格式，试试这个:

#include <sys/time.h>
struct timeval tv;
gettimeofday(&tv,NULL);
double perciseTimeStamp = tv.tv_sec + tv.tv_usec * 0.000001;

这应该给你完全相同的结果[[NSDate date] timeIntervalSince1970]

如果你正在考虑使用这个相对定时(例如游戏或动画)，我宁愿使用CACurrentMediaTime()

double CurrentTime = CACurrentMediaTime();

哪一种是推荐的方式;NSDate从网络的同步时钟中提取，并且在与网络重新同步时偶尔会打嗝。

它返回当前的绝对时间，以秒为单位。

如果你只想要小数部分(通常在同步动画时使用)，

let ct = CACurrentMediaTime().truncatingRemainder(dividingBy: 1)

CFAbsoluteTimeGetCurrent ()

Absolute time is measured in seconds relative to the absolute reference date of Jan 1 2001 00:00:00 GMT. A positive value represents a date after the reference date, a negative value represents a date before it. For example, the absolute time -32940326 is equivalent to December 16th, 1999 at 17:54:34. Repeated calls to this function do not guarantee monotonically increasing results. The system time may decrease due to synchronization with external time references or due to an explicit user change of the clock.