到目前为止，我发现gettimeofday在iOS (iPad)上是一个很好的解决方案，当你想执行一些间隔评估(比如帧速率，渲染帧的计时……):

#include <sys/time.h>
struct timeval time;
gettimeofday(&time, NULL);
long millis = (time.tv_sec * 1000) + (time.tv_usec / 1000);

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.

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)

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)
    }

let timeInMiliSecDate = Date()
let timeInMiliSec = Int (timeInMiliSecDate.timeIntervalSince1970 * 1000)
print(timeInMiliSec)

到目前为止，我发现gettimeofday在iOS (iPad)上是一个很好的解决方案，当你想执行一些间隔评估(比如帧速率，渲染帧的计时……):

#include <sys/time.h>
struct timeval time;
gettimeofday(&time, NULL);
long millis = (time.tv_sec * 1000) + (time.tv_usec / 1000);