//计算两个日期之间的天数
- (NSInteger)calcDaysFromBegin:(NSDate *)beginDate end:(NSDate *)endDate {
NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm"];
//取两个日期对象的时间间隔:
NSTimeInterval time= [endDate timeIntervalSinceDate:beginDate];
int days=((int)time)/ (3600*24);
return days;
}