比较两个日期的大小

/**
*  比较两个日期的先后顺序
*
*  @param oneDay     时间1
*  @param anotherDay 时间2
*
*  @return 1: 时间1是未来的时间;  返回-1:时间1是过去的时间;  返回0:两个时间相等
*/
+(int)compareOneDay:(NSDate *)oneDay withAnotherDay:(NSDate *)anotherDay
{
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd"];
NSString *oneDayStr = [dateFormatter stringFromDate:oneDay];
NSString *anotherDayStr = [dateFormatter stringFromDate:anotherDay];
NSDate *dateA = [dateFormatter dateFromString:oneDayStr];
NSDate *dateB = [dateFormatter dateFromString:anotherDayStr];
NSComparisonResult result = [dateA compare:dateB];
NSLog(@"date1 : %@, date2 : %@", oneDay, anotherDay);
if (result == NSOrderedDescending) {
//NSLog(@"Date1  is in the future");
return 1;
}
else if (result == NSOrderedAscending){

//NSLog(@"Date1 is in the past");
return -1;
}
//NSLog(@"Both dates are the same");
return 0;

}