字符串转换时间，时区问题

1.字符串转化为时间，解决了关于相差8个小时的时区问题

    NSString *dateStr= @"2012-05-17 11:23:23";

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

    

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

    

    NSDate *fromdate=[format dateFromString:dateStr];

    

    NSTimeZone *fromzone = [NSTimeZone systemTimeZone];

    

    NSInteger frominterval = [fromzone secondsFromGMTForDate: fromdate];

    

    NSDate *fromDate = [fromdate  dateByAddingTimeInterval: frominterval];

    

    NSLog(@"fromdate=%@",fromDate);