NSNumber和NSTimeInterval

Question

I am trying to get the system time in milliseconds. For that I have declared:

 NSNumber *createdTimeInMilliSec; //in class declaration

and in one of my instance functions, I doing:

 self.createdTimeInMilliSec= ([NSDate timeIntervalSinceReferenceDate]*1000); //ERROR: incompatible type for argument 1 of 'setCreatedTimeInMilliSec:'

timeIntervalSinceReferenceDate returns in NSTimeInterval , so how to convert that into NSNumber ? Or what I am doing wrong?

Answer 1

NSTimeInterval is typedefed as follow : typedef double NSTimeInterval; .

To create a NSNumber with, use :

NSNumber *n = [NSNumber numberWithDouble:yourTimeIntervalValue];

Answer 2

I'm not sure it's clear from the other answers - but NSTimeInterval is actually just a typedef'ed double. You can get an NSNumber from it by doing [NSNumber numberWithDouble:timeInterval] or even more succinctly @(timeInterval) .

Answer 3

NSTimeInterval is a typedef for a double. So use NSNumber 's convenience constructor numberWithDouble: as follows:

self.createdTimeInMilliSec= [NSNumber numberWithDouble:([NSDate timeIntervalSinceReferenceDate]*1000)];

Answer 4

由于NSTimeInterval是双倍的，你可以做到

NSNumber *myNumber = [NSNumber numberWithDouble: myTimeInterval];