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Edit:

I solved this problem by adding the process identifier that is exposed from the NSXPCConnection class as that is unique per connection as the key.

Problem:

I'm facing a problem where I need to store a key-value pair in a NSMutableDictionary (where an object of type NSXPCConnection is stored as the key). But I'm unable to do so as NSXPCConnection does not conform to NSCopying.

This is my code:

- (void)addDataToDict:(MyClass *)obj Connection:(NSXPCConnection *)connection
{   
    assert(obj);
    
    LogInfo("Assert success");
    
    if([_dict objectForKey:connection])
    {
        LogError("Connection already in dictionary, abort");
        return;
    }
    else
        LogInfo("Adding connection to dict");
    
    NSObject<NSCopying> *key = connection;
    
    [_dict setObject:obj forKey:key];
}

But this throws the following warning:

Incompatible pointer types initializing 'NSObject<NSCopying> *' with an expression of type 'NSXPCConnection *'

and the following error during runtime:

-[NSXPCConnection copyWithZone:]: unrecognized selector sent to instance 0x127a4b0d0

Any suggestions on how I can do this better are welcome!

jormen651
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1 Answers1

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Although you've already solved this for your specific use-case by using a different key type, one alternative is to use an NSMapTable, which behaves very much like NSDictionary but allows you to have different semantics for keys and values.

Specifically, for this use-case, a +strongToStrongObjectsMapTable would be appropriate as it retains keys instead of copying them, allowing you to key by non-NSCopying objects like NSXPCConnection.

Itai Ferber
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  • Ah - this is exactly what I was looking for. But I was kind of reluctant to save the connection directly (for memory purposes) but this is good info for the future! – jormen651 Feb 15 '22 at 06:05