Convert NSString to a Time, and then calculate "Time Until"

Question

I have been on SO for awhile now trying to get this problem solved but have not had any luck.

In a nutshell I want to take a string like this: "2011-11-21 11:20:00" and calculate the "Time Until". In a format like "1 day 36 mins" which would be a string I could display in a label.

I cant wrap my head around this. Anyone have some sample code from doing this before? Any help would be greatly appreciated.

Answer 1

This code should help you out.

    NSDate * date;

    //Assume dateString is populated and of format NSString * dateString =@"2011-11-21 11:20:00";
    NSDateFormatter * dateFormatter = [[NSDateFormatter alloc] init];

    //EDITED date formatter to correct behavior
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    if (dateString != nil)  {
        date = [dateFormatter dateFromString:dateString];
    }
    [dateFormatter release];

    NSTimeInterval difference = [date timeIntervalSinceDate:[NSDate date]];
    int days = difference/(3600*24);
    difference -= (float) (days*3600*24);
    int hours = difference/(3600);
    difference -= (float) (hours*3600);
    int minutes = difference/(60);

    NSString * timeRemaining = [NSString stringWithFormat:@"%dd %dh %dm", days, hours, minutes];