日期，时区

    NSDateFormatter *format = [[NSDateFormatter alloc] init];

    [format setLocalizedDateFormatFromTemplate:@"yyyy-MM-dd HH:mm:ss"];

    [format setTimeZone:[NSTimeZone systemTimeZone]];

    NSLog(@"%@",[format stringFromDate:[NSDate date]]);

    

    NSCalendar *calendar1 = [NSCalendar currentCalendar];

    [calendar1 setTimeZone:[NSTimeZone systemTimeZone]];

    NSLog(@"%ld",[calendar1 component:NSHourCalendarUnit fromDate:[NSDate date]]);

 

　　NSDate *date = [NSDate date];

　　NSTimeZone *zone = [NSTimeZone systemTimeZone];

　　NSInteger interval = [zone secondsFromGMTForDate: date];

　　NSDate *localeDate = [date  dateByAddingTimeInterval: interval];  

　　NSLog(@"%@", localeDate);