Local declaration of tableView hides instance variable?

I understand why I get the warning in the title when I define my own tableView property in my own class and then use a local varia开发者_开发技巧ble name tableView.

What I want to know is why DON'T I get this warning when I derive my class from UITableViewController, which has it's own tableView property? Does the compiler/editor only look at my class and not the parent class?

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When you’re implementing a method, parameters/local variables share the same namespace as instance variables. However, they don’t share the same namespace as declared properties, which means that a class can declare a property named someData (or inherit it from one of its superclasses), have the backing instance variable with some other name, and the implementation of a method of that class can also have a parameter/local variable named someData — the compiler won’t give a warning in that case.

I assume you have a declared property named tableView and also an instance variable named tableView, the latter being either explicitly declared in the interface or automatically created when synthesizing the property. In that case, if you define a method that takes a parameter named tableView or declares a local variable named tableView, this local declaration will hide the instance variable named tableView (but not the property).

In the case of UITableViewController, there is no instance variable named tableView. There is a declared property named tableView which, because it’s in a different namespace, won’t be hidden by a local (variable) declaration.

One easy fix to avoid the compiler warnings is to give a different name to the instance variable. For instance, the instance variable can be named _tableView, and the property would still be named tableView but synthesized as @synthesize tableView = _tableView.

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Post the exact code that is generating the warning.

"Local declaration" typically implies that you have something like:

- (void) foo {
    int thisIsTheNameOfAnInstanceVariable;
}

There are likely other permutations via which you could cause this to happen, though.

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I'm not exactly sure if I'm answering this correctly, but if you want to access variables in the super classes (e.g. UITableView, since your class is deriving form it) you have to use "self." then the variable name form the super class. Whenever you directly call a variables, e.g. 'myVariable', it will only look for local instances.