iPhone: How to get current milliseconds?

What is the best way to get the current system time milliseconds?

If you're looking at using this for relative timing (for example for games or animation) I'd rather use CACurrentMediaTime()

double CurrentTime = CACurrentMediaTime();

Which is the recommended way; NSDate draws from the networked synch-clock and will occasionally hiccup when re-synching it against the network.

It returns the current absolute time, in seconds.

If you want only the decimal part (often used when syncing animations),

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

[[NSDate date] timeIntervalSince1970];

It returns the number of seconds since epoch as a double. I'm almost sure you can access the milliseconds from the fractional part.

I benchmarked all the other answers on an iPhone 4S and iPad 3 (release builds). CACurrentMediaTime has the least overhead by a small margin. timeIntervalSince1970 is far slower than the others, probably due to NSDate instantiation overhead, though it may not matter for many use cases.

I'd recommend CACurrentMediaTime if you want the least overhead and don't mind adding the Quartz Framework dependency. Or gettimeofday if portability is a priority for you.

iPhone 4S

CACurrentMediaTime: 1.33 µs/call
gettimeofday: 1.38 µs/call
[NSDate timeIntervalSinceReferenceDate]: 1.45 µs/call
CFAbsoluteTimeGetCurrent: 1.48 µs/call
[[NSDate date] timeIntervalSince1970]: 4.93 µs/call

iPad 3

CACurrentMediaTime: 1.25 µs/call
gettimeofday: 1.33 µs/call
CFAbsoluteTimeGetCurrent: 1.34 µs/call
[NSDate timeIntervalSinceReferenceDate]: 1.37 µs/call
[[NSDate date] timeIntervalSince1970]: 3.47 µs/call

In Swift we can make a function and do as follows

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

var currentTime = getCurrentMillis()

Though its working fine in Swift 3.0 but we can modify and use the Date class instead of NSDate in 3.0

Swift 3.0

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

var currentTime = getCurrentMillis()