Instantiate an arbitrary class in Objective C

Question

I have an NSMutableArray of objects in Objective C. I'm filling this up based on the contents of a data file, which contains the class each element should be and a list of parameters. All of the possible classes inherit from a common parent class.

Is there any way of instantiating each element of the array without hard-coding each of the possible classes inside a massive if-else test?

Answer 1

Yes, I guess memset() will be of help

Answer 2

You currently store the name of the class in the data file as well as the object's parameters.

You can therefore use NSClassFromString to instantiate that custom class object and initialize its state:

NSString *_myCustomClass = // get custom class name from data file...
id _myCustomObject = [[NSClassFromString(_myCustomClass) alloc] init];
// set up _myCustomObject's state from data file's parameters...
[_myMutableArray addObject:_myCustomObject];
[_myCustomObject release];

Answer 3

If you're in control of writing that data file too, you might find it easier to just use standard objective C archiving (called serialization in other languages). It's an easy way to write and read objects into and from a file.