学步园

获取时间、考虑时区、时间格式

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    
    //获取当前时间
    NSDate *now = [NSDate date];
    NSLog(@"It's %@ now,",now);
    
    //获取距离某个时间点的时间
    NSDate *then = [[NSDate alloc] initWithTimeInterval:3600 sinceDate:now];
    NSLog(@"after 3600 second:%@",then);
    
    //考虑时区
    NSTimeZone *zone = [NSTimeZone systemTimeZone];
    NSInteger interval = [zone secondsFromGMTForDate:now];
    NSDate *localDate = [now dateByAddingTimeInterval:interval];
    NSLog(@"the local date is %@",localDate);
    
    //时间格式
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    
    [dateFormatter setDateFormat:@"年月日 YYYY/mm/dd 时间 hh:mm:ss"];  //设置时间格式
    NSString *dateString = [dateFormatter stringFromDate:[NSDate date]];
    NSLog(@"dateString = %@",dateString);
    
    [dateFormatter setDateFormat:@"YYYY-MM-dd"];
    NSString *date = [dateFormatter stringFromDate:[NSDate date]];
    NSLog(@"年月日 date = %@",date);
    
    [dateFormatter setDateFormat:@"hh:mm:ss"];
    NSString *time = [dateFormatter stringFromDate:[NSDate date]];
    NSLog(@"时间 time = %@",time);
}

日期的比较