What is the proper way to access local variables in a delegate?

Question

I'm trying to access an NSMutableArray which is a data member of my AppDelegate class. It is synthesized in the implementation, and is an array of a custom class which has a "name" NSString data member.

I currently use it to fill a Table View (a SubView) like this:

cell.textLabel.text = [[[delegate contentArray] objectAtIndex:indexPath.row] name];

This works, but I get a warning:

warning: no '-contentArray' method found

It won't compile as:

cell.textLabel.text = [[delegate.contentArray objectAtIndex:indexPath.row] name];

I get this in that case:

error: request for member 'contentArray' in something not a structure or union

What is the proper way to access an array in the delegate?

Update: To declare delegate, in the table view controller header file, I include @class MainAppDelegate; and in the @interface I declare a data member MainAppDelegate *delegate;. In the table view controller's @implementation I do @synthesize delegate;.

Answer 1

You wil have to cast the delegate to the correct type. Like this:

cell.textLabel.text = [[[(MyAppDelegate*) delegate contentArray]
    objectAtIndex:indexPath.row] name]

Answer 2

I think I solved it. The MainAppDelegate.h header file was not imported into the table view controller's .m file. I guess it doesn't make sense to me to have both the main AppDelegate.h file and the table view's ViewController.h file both importing each other.

Answer 3

To declare delegate, in the table view controller header file, I include @class MainAppDelegate; and in the @interface I declare a[n instance variable] MainAppDelegate *delegate;. In the table view controller's @implementation I do @synthesize delegate;.

So you have forward-declared the class name MainAppDelegate and used it to declare an instance variable. Since you are @synthesizing a property, I assume you declared one of those, too.

I currently use it to fill a Table View (a SubView) like this:

cell.textLabel.text = [[[delegate contentArray] objectAtIndex:indexPath.row] name];

This works, but I get a warning:

warning: no '-contentArray' method found

It won't compile as:

cell.textLabel.text = [[delegate.contentArray objectAtIndex:indexPath.row] name];

I get this in that case:

error: request for member 'contentArray' in something not a structure or union

That's because the compiler doesn't know what methods or properties delegate has. You've declared the name of its class, but the compiler doesn't know anything else about it, because you haven't provided an @interface for that class.

The solution is to #import the header file for the delegate class into the table view controller class's implementation file, probably immediately after #importing the table view controller class's own header.

Also, I suspect that the array more properly belongs to the table view controller than to the app delegate, but I don't know enough about Cocoa Touch to say for sure.