NSDate获得当前应用程序系统时间

  NSTimeZone *zone = [NSTimeZone defaultTimeZone];//获得当前应用程序默认的时区

    NSInteger interval = [zone secondsFromGMTForDate:[NSDate date]];//以秒为单位返回当前应用程序与世界标准时间（格林威尼时间）的时差

    NSDate *localeDate = [[NSDate date] dateByAddingTimeInterval:interval];

    NSDate *nowDate=[NSDate dateWithTimeIntervalSinceNow:interval];

    UIDatePicker *datePicker=[[UIDatePicker alloc] init];

    [datePicker setDate:nowDate];

    NSLog(@"datePicker==%@",[datePicker date]);

    NSLog(@"interval===%i",interval);

    NSLog(@"localeDate==%@",localeDate);

    NSLog(@"nowDate==%@",nowDate);

    NSLog(@" [localeDate description]==%@", [localeDate description]);

  NSDate *date=[[NSDate alloc] initWithTimeIntervalSinceNow:0];   

NSLog(@" date ==%@", date);