NSTimeInterval time = ([[NSDate date] timeIntervalSince1970]); //double
long digits = (long)time; //first 10 digits        
int decimalDigits = (int)(fmod(time, 1) * 1000); //3 missing digits
/*** long ***/
long timestamp = (digits * 1000) + decimalDigits;
/*** string ***/
NSString *timestampString = [NSString stringWithFormat:@"%ld%03d",digits ,decimalDigits];

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);

It may be useful to know about CodeTimestamps, which provide a wrapper around mach-based timing functions. This gives you nanosecond-resolution timing data - 1000000x more precise than milliseconds. Yes, a million times more precise. (The prefixes are milli, micro, nano, each 1000x more precise than the last.) Even if you don't need CodeTimestamps, check out the code (it's open source) to see how they use mach to get the timing data. This would be useful when you need more precision and want a faster method call than the NSDate approach.

http://eng.pulse.me/line-by-line-speed-analysis-for-ios-apps/

如果你不想包含Quartz框架，[NSDate timeintervalsincerely eferencedate]是另一个选项。它返回一个double，表示秒数。

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

在Swift中，我们可以创建一个函数，并如下所示

func getCurrentMillis()->Int64{
    return  Int64(NSDate().timeIntervalSince1970 * 1000)
}

var currentTime = getCurrentMillis()

虽然它在Swift 3.0中工作得很好，但我们可以修改和使用Date类而不是3.0中的NSDate

斯威夫特3.0

func getCurrentMillis()->Int64 {
    return Int64(Date().timeIntervalSince1970 * 1000)
}

var currentTime = getCurrentMillis()