False order when reading Dictionary from PList

Question

Hi, I have a plist from which i am trying to access its animations in sequence (as defined in the PList) but when I store it in NSDictionary and then try to play animation one by one it is not playing them in sequence. e.g,

int index = 0;
[self playAnimation:[animTypes objectAtIndex:index++]];
[self playAnimation:[animTypes objectAtIndex:index++]];

This is the code of my Plist:

<plist version="1.0">
<dict>
<key>Boy</key>
    <dict>
    <key>Enter</key>
    <dict>
        <key>disabled</key>
        <false/>
        <key>halfCycle</key>
        <true/>
        <key>fps</key>
        <integer>1</integer>
        <key>defaultFrame</key>
        <integer>0</integer>
        <key>useZwoptex</key>
        <true/>
        <key>frames</key>
        <array>
            <string>boy-000.png</string>
        </array>
    </dict>
    <key>Jump</key>
    <dict>
        <key>disabled</key>
        <false/>
        <key>halfCycle</key>
        <true/>
        <key>fps</key>
        <integer>13</integer>
        <key>defaultFrame</key>
        <integer>0</integer>
        <key>useZwoptex</key>
        <true/>
        <key>frames</key>
        <array>
            <string>boyjump-000.png</string>
            <string>boyjump-001.png</string>
            <string>boyjump-002.png</string>
        </array>
    </dict>
    <key>Turnaround</key>
    <dict>
        <key>disabled</key>
        <false/>
        <key>halfCycle</key>
        <true/>
        <key>fps</key>
        <integer>21</integer>
        <key>defaultFrame</key>
        <integer>0</integer>
        <key>useZwoptex</key>
        <true/>
        <key>frames</key>
        <array>
            <string>boyturnaround-000.png</string>
            <string>boyturnaround-001.png</string>
            <string>boyturnaround-002.png</string>
        </array>
    </dict>
</dict>
</plist>

---

Plz guide me how to load the animations in sequence?

Answer 1

Dictionarys don't store objects in order in a sequence like an array, they store key-value pairs so the structure could in effect be in any order.

I suggest putting your NSDict objects (that define your animation sequences) in an NSArray

<plist version="1.0">
<array>
    <dict>
        <key>Name</key>
        <string>Boy</string>
        <key>disabled</key>
        <false/>
        <key>halfCycle</key>
        <true/>
        <key>fps</key>
        <integer>1</integer>
        <key>defaultFrame</key>
        <integer>0</integer>
        <key>useZwoptex</key>
        <true/>
        <key>frames</key>
        <array>
            <string>boy-000.png</string>
        </array>
    </dict>
    <dict>
        <key>Name</key>
        <string>Jump</string>
        <key>disabled</key>
        <false/>
        <key>halfCycle</key>
        <true/>
        <key>fps</key>
        <integer>13</integer>
        <key>defaultFrame</key>
        <integer>0</integer>
        <key>useZwoptex</key>
        <true/>
        <key>frames</key>
        <array>
            <string>boyjump-000.png</string>
            <string>boyjump-001.png</string>
            <string>boyjump-002.png</string>
        </array>
    </dict>
    <dict>
        <key>Name</key>
        <string>Enter</string>
        <key>disabled</key>
        <false/>
        <key>halfCycle</key>
        <true/>
        <key>fps</key>
        <integer>21</integer>
        <key>defaultFrame</key>
        <integer>0</integer>
        <key>useZwoptex</key>
        <true/>
        <key>frames</key>
        <array>
            <string>boyturnaround-000.png</string>
            <string>boyturnaround-001.png</string>
            <string>boyturnaround-002.png</string>
        </array>
    </dict>
</array>
</plist>

Answer 2

Yes, djhworld is correct - NSDictionary objects don't return entries in the order they're created.

I'm fairly new to Objective C and came up against the very same problem. The solution I cooked up allowed me to still use a single NSDictionary, but before using it I sort the entries based on the key. In a util class, I sort the keys and return a sorted array:

+(NSArray *) sortedKeysForDictionary:(NSDictionary *)dict {
    NSArray *keys = [dict allKeys];
    NSMutableArray *anArray = [NSMutableArray arrayWithArray:keys];
    keys = [anArray sortedArrayUsingSelector:@selector(localizedCompare:)]; 
    return keys;
}

Then I just run through the keys pulling them from the Dictionary in order...

-(void) processEntries {
    NSArray *keys = [Utils sortedKeysForDictionary:myDictionary];
    for (int i=0; i<keys.count; i++){
        NSString *key = [keys objectAtIndex:i];
        id dictEntry = [myDictionary valueForKey:key];

        // process the entry here

    }

}

The only caveat is that you have to use keys that sort properly. I've adopted a convention of using keys in the form nnn:keyName, so I can sort them but still provide human-readable names. e.g. 001:process XYZ.