Properties for Class and Its Subclasses Only

objective-c properties protected instance-variables
Jay Haase picture Jay Haase · Nov 24, 2010 · Viewed 13.4k times · Source

Is it possible to define properties that are only available to the class they are defined in, and that class's subclasses?

Stated another way, is there a way to define protected properties?

Answer

Dave DeLong picture Dave DeLong · Nov 24, 2010

Technically, no. Properties are really just methods, and all methods are public. The way we "protect" methods in Objective-C is by not letting other people know about them.

Practically, yes. You can define the properties in a class extension, and still @synthesize them in your main implementation block.

Related questions

Workaround to accomplish protected properties in Objective-C

I've been trying to find a workaround to declare @protected properties in Objective-C so only subclasses in the hierarchy can access them (read only, not write). I read that there is no documented way of doing this so I thought …

Read More
What's the difference between the atomic and nonatomic attributes?

What do atomic and nonatomic mean in property declarations? @property(nonatomic, retain) UITextField *userName; @property(atomic, retain) UITextField *userName; @property(retain) UITextField *userName; What is the operational difference between these three?

Read More
Objective-C ARC: strong vs retain and weak vs assign

There are two new memory management attributes for properties introduced by ARC, strong and weak. Apart from copy, which is obviously something completely different, are there any differences between strong vs retain and weak vs assign? From my understanding, the …

Read More