日期比较

//时间比较
-(BOOL)compareDate:(NSString*)startDateStr withDate:(NSString*)endDateStr{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy-MM-dd"];
    
    NSDate *startDate = [formatter dateFromString:startDateStr];
    NSDate *endDate = [formatter dateFromString:endDateStr];
    
    NSComparisonResult result = [startDate compare:endDate];
    if (result == NSOrderedDescending) {
        return NO;
    } else if (result == NSOrderedAscending) {
        return YES;
    } else if (result == NSOrderedSame) {
        return YES;
    }
    return YES;
}