Question

I’m sorry for the little confusing title but say I have a class with an interface that looks like this:

@interface Class : NSObject {

    NSArray *items;
}

@property (nonatomic, retain) NSArray *items;

@end

In the impementation I actually want to do some adding operations thus using NSMutableArray and then the user using the class should be able to retrieve the data as an NSArray.

Answer 1

Declare mutable array as instance variable, declare the property as readonly NSArray and overwrite the getter.

@interface SomeClass : NSObject {

    NSMutableArray *mutableItems;
}

@property (nonatomic, readonly) NSArray *items;

@end

@implementation SomeClass

- (NSArray *)items {
    return [NSArray arrayWithArray:mutableItems];
}

@end