ios - Convert a NSDate to milliseconds epoch time

Question

I need to be able to convert a date to a time stamp, an epoch in milliseconds. All I see online are for converting milliseconds to NSDate and not the other way round. Any help out there?

Answer 1

NSTimeInterval is a double that already contains sub-second data after the decimal point. Depending what you need, your conversion could be a simple as multiplying by 1000.

- (void)testDateFormat
{
    NSDate *date = [NSDate date];
    NSLog(@"Time: %f", floor([date timeIntervalSince1970] * 1000));
    NSLog(@"Time: %f", floor([date timeIntervalSince1970]));
    NSLog(@"Time: %lli", [@(floor([date timeIntervalSince1970] * 1000)) longLongValue]);
    NSLog(@"Time: %lli", [@(floor([date timeIntervalSince1970])) longLongValue]);
}

// Result
// 2013-04-15 13:28:11.284 TestApp[10469:907] Time: 1366057691284.000000
// 2013-04-15 13:28:11.286 TestApp[10469:907] Time: 1366057691.000000
// 2013-04-15 13:28:11.287 TestApp[10469:907] Time: 1366057691284
// 2013-04-15 13:28:11.288 TestApp[10469:907] Time: 1366057691