iOS当前时间和后台返回时间做比较大小

#pragma mark -得到当前时间
- (NSDate *)CurrentTime{
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
    //当前时间格式
    [formatter setDateFormat:@"yyyy-MM-dd"];
    NSString *dateTime=[formatter stringFromDate:[NSDate date]];
    NSDate *date = [formatter dateFromString:dateTime];

    NSLog(@"---------- currentDate == %@",date);
    return date;
}
#当前时间和后台返回的时间比较方法，返回一个int类型的数据
//oneDay:当前时间
//anotherDay:返回时间
- (int)compareCurrentTimeDay:(NSDate *)oneDay withAnotherDay:(NSDate *)anotherDay
{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    //这个时间格式需要和当前得到时间格式相同才能做比较
    [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");
        //当前时间大于返回时间
        return 1;
    }
    else if (result == NSOrderedAscending){
        //NSLog(@"Date1 is in the past");
        //当前时间小于返回时间
        return -1;
    }
    //NSLog(@"Both dates are the same");
    //完全相等（NSOrderedDescending，NSOrderedAscending，NSOrderedSame这三个是一个枚举类型）
    return 0;

}