Question

NSData* myData = [NSData dataWithBytes:&pEvent length:sizeof(pEvent)];
    wTimerId = 99;

    [m_cAppIdMap setObject:myData forKey:[NSNumber numberWithUnsignedShort:wTimerId]];
    wTimerId = 96;
    [m_cAppIdMap setObject:myData forKey:[NSNumber numberWithUnsignedShort:wTimerId]];
    wTimerId = 97;
    [m_cAppIdMap setObject:myData forKey:[NSNumber numberWithUnsignedShort:wTimerId]];
    wTimerId = 98;
    [m_cAppIdMap setObject:myData forKey:[NSNumber numberWithUnsignedShort:wTimerId]];
    wTimerId = 95;
    [m_cAppIdMap setObject:myData forKey:[NSNumber numberWithUnsignedShort:wTimerId]];

I’m storing the data with the key value in the order 99,96,97,98,95. But it gets stored as

{
    98 = <b0c71000 01000000>;
    97 = <b0c71000 01000000>;
    96 = <b0c71000 01000000>;
    99 = <b0c71000 01000000>;
    95 = <b0c71000 01000000>;
}

why is it so.Is there any way to arrange the dictionary in the way which gets stored first.

Answer 1

Dictionaries are inherently unordered. If you want order, use an array.

If you want both order and key based lookup, store both the array and dictionary; one to preserve order, the other to preserve key based lookup.

Just keep ’em in sync.