iOS - How to Calculate Age in iPhone

use timeIntervalSinceDate 


 NSString *selectDate = @"05/29/1984";
    NSDate *currentDate = [NSDate date];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"MM/dd/yyyy"];
    int time = [currentDate timeIntervalSinceDate:[dateFormatter dateFromString:selectDate]];

NSLog(@"time pass %d',time)

// get num  of day count ((time / 60) / 60) / 24