Unrecognized selector when adding an object to NSMutableArray

Question

I have a singleton class with a NSMutableArray property to which I want to add objects and remove objects. For some reason I am getting:

-[__NSDictionaryI s         


        

Answer 1

Your

@property (nonatomic, copy) NSMutableDictionary *p_outbox;

is creating a copy of that object which you assign to it. As you are assigning a NSMutableDictionary to it, it's creates a copy of NSMutableDictionary object which is NSDictionary which is not a mutable copy.

So change it to

For Non ARC

@property (nonatomic, retain) NSMutableDictionary *p_outbox;

For ARC

@property (nonatomic, strong) NSMutableDictionary *p_outbox;

Answer 2

The problem is with your property:

@property (nonatomic, copy) NSMutableDictionary *p_outbox;

The copy semantics of the property result in a copy of the dictionary being made when you assign a value to the property. But the copy method for a dictionary always returns an immutable NSDictionary, even when called on an NSMutableDictionary.

To solve this problem you must create your own setter method for the property:

// I'm a little unclear what the actual name of the method will be.
// It's unusual to use underscores in property names. CamelCase is the standard.
- (void)setP_outbox:(NSMutableDictionary *)dictionary {
    p_outbox = [dictionary mutableCopy];
}