NSDate*date = [NSDate date];// 获得时间对象
NSDateFormatter *forMatter = [[NSDateFormatter alloc] init];
NSTimeZone *zone = [NSTimeZone systemTimeZone]; // 获得当前系统的时区
[forMatter setTimeZone:zone];// 设定时区
[forMatter setDateFormat:@"yyyyMMdd"];
NSString*dateStr = [forMatter stringFromDate:date];
