I got a new solution about how long have you been alive

Objective-C Programming (2nd Edition) 14. More Messages
1

this is the codes below:
#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
@autoreleasepool {
NSDate *borntime = [NSDate dateWithTimeIntervalSinceReferenceDate: 1987-12-30];
NSDate *now = [NSDate date];
unsigned int seconds = [now timeIntervalSinceDate:borntime];
NSLog(@“I have born %u seconds”,seconds);
// insert code here…

    NSDateComponents *comps = [[NSDateComponents alloc] init];
    [comps setYear:1999];
    [comps setMonth:12];
    [comps setDay:9];
    [comps setHour:10];
    [comps setMinute:50];
    [comps setSecond:21];
    NSCalendar *g = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    NSDate *date0fBirth = [g dateFromComponents:comps];
    NSLog(@"Jack's date of birth is %@.",date0fBirth);
    NSLog(@"Hello, World!");
}
return 0;

}