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I’m a C/C++ coder who is just starting to learn Objective-C. I have run into a few snags with the memory management sytem: release, autorelease, and retain. For example, I understand that some methods will retain an object that is passed in as a parameter and others will not.

Does the method setDataSource: of NSTableView retain its parameter? For example, what is the correct syntax for adding a new empty array as the data source? This is what I have, but I don’t know if it is correct:

[myTableView setDataSource:[NSMutableArray array]];

Does the array returned by [NSMutableArray array] have a retain count of 1? Is that ok? Is this programatically stupid???

it’s an autoreleased array. it will be released at the end of the current run loop.

One other question, do I need to retain/autorelease with this call?

[myTableView setDataSource:[NSMutableArray arrayWithObject:someDictionary]]

you would need to retain it, but see below…

Thanks for any help, JoeCrow.

No, a tableview will not retain its data source - it doesn’t own it, it just asks it for data to display. You can’t use an array as a data source for a table view anyway (unless you’ve added the NSTableDataSource protocol methods as a category on NSArray.) A NSTableView’s dataSource can be any class that implements the required methods from the NSTableDataSource protocol. You would typically have the data source be a NSWindowController subclass that is acting as FilesOwner for the table view’s nib if you’re loading the table view in a separate nib, or else you could use your NSDocument class or app delegate.

What if I’m using a “Table Delegate”?

A table’s delegate has no real effect on its data source - they’re often the same object, but mostly for convenience or it “just makes sense” to do it that way.