减少Objective-C中的时间

Question

I have a number of hours and a number of minutes, and I want a reduce the time of 1 second. So, I think I must create a nsdate object with my time, and after find the method to decrease the time. I looked in the apple documentation but I don't find how to do this.

Answer 1

You can use this

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MM/dd/yyyy"];
NewDateString = [formatter stringFromDate:[NSDate dateWithTimeIntervalSinceNow:-1]

Answer 2

You want NSDateComponents . Note, you need to use it with a specific calendar. A code example is listed on the page to which I linked.

Answer 3

Don't reinvent the wheel. There are many open source NSDate additions that you can use here. See here