Question

So I’m having trouble with OOAD, properties, the self keyword, etc. I wanted to just create a simple test project that has a UITableView. I have an ivar of

NSArray *tableData;

how would I write a setter and getter method for this? I thought my setter would look like:

- (void)setTableData:(NSArray *)array {
    [tableData autorelease];
    tableData = [array retain];
}

Then when I try to use this method in my viewDidLoad, I realize that I need to create an instance of my ViewController. This seems like what not to do when I look at how it’s done in books where they create a property for the NSArray, then in viewDidLoad just do a

NSArray *array = [[NSArray alloc] initWithObjects:@"1", @"2", @"3", @"4", nil];
    self.tableData = array;
[array release];

I’m kind of just trying to understand what goes on behind the scenes, to try to understand OOAD principles, ivars, properties, self, etc. Thanks in advance.

Answer 1

I’m sure you already know that using @synthesize will create setter/getter methods for you, but it’s good to know what’s going on “under the hood” to understand the concepts.

As far as a setter method goes, you’re probably better off with something like this:

- (void)setTableData:(NSArray *)array {
    if (tableData != array) {
        [tableData release];
        tableData = [array retain];
    }
}

This basically checks to make sure the new array is actually different than the current. If it is, it releases the old instance and sets the new one.

For a getter method, just use:

- (NSArray *)tableData (
    return tableData;
}

This can be accessed by calling self.tableData. And of course setting the array is done just as you have done, with self.tableData = array;

I hope that helps. If you need more information, just say so and I’ll be happy to try and explain further