//获取时间字符串--
HUD.detailsLabelText=[NSString stringWithFormat:@"%@",_currentDate.text];
-(void)updateLabel {
//获得系统日期
NSDate * senddate=[NSDate date];
NSDateFormatter *dateformatter=[[NSDateFormatter alloc] init];
[dateformatter setDateFormat:@"上次更新时间: YYYY年MM月dd日 HH:mm:ss"];
NSString * locationString=[dateformatter stringFromDate:senddate];
_currentDate.text=locationString;
[dateformatter release];
}