NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"MM/dd/yyyy hh:mm:ss a";
NSString *dateString = @"12/24/2014 10:32:42 PM";
NSDate *date = [formatter dateFromString:dateString];
NSLog(@"date: %@", [formatter stringFromDate:date]);
Next thing you'll need to figure out is the time zones.