How do I count time in iOS?
ios, nsdate, nstimeinterval, nstimer, objective-c
Solution
Your second approach is correct. Save the current date in an `NSDate` object and use `timeIntervalSinceDate:` to get the passed time since then. The result will be of type `NSTimeInterval` which is a floating point number. It specifies time differences in seconds, but since it's a floating point number it can store fractions of a second as well.
NSTimeInterval is always specified in seconds; it yields sub-millisecond precision over a range of 10,000 years.
Problem
I don't want to set up a timer that "fires" (and does something) after a certain amount of time has passed. Therefore, I'm not interested in the `NSTimer` class and its methods. All I'm interested in is counting the time that passes by while, for example, some while-loop is executing. I could use `NSDate` as follows I guess : ``` NSDate currentDate = [[NSDate alloc] init]; while(someConditionIsTrue) { // executing.. } timeElapsed = [self timeIntervalSinceDate:currentDate]; NSLog(@"time elapsed was: %i", timeElapsed); ``` However, if I understand correctly, `timeIntervalSinceDate:` can only count seconds. Is there a way I can count the time that is passing by in milliseconds? In other words, what is the smallest unit I can count passing time in and how ?