How should objects be stored using weak references inside collections?

To store objects using weak references within collections in iOS (Swift or Objective-C), special containers are usually used that do not hold strong references to objects, to avoid retain cycles and memory leaks.

In Swift, you can use NSHashTable or NSMapTable with the weak references option:

let weakSet = NSHashTable<AnyObject>.weakObjects()
weakSet.add(someObject)

This allows storing objects without increasing the reference count, and when an object is deallocated, it is automatically removed from the collection.

If you use regular collections (like arrays), you can wrap objects in a helper structure for weak references:

class WeakRef<T: AnyObject> {
    weak var value: T?
    init(value: T) {
        self.value = value
    }
}

var weakArray: [WeakRef<MyClass>] = []
weakArray.append(WeakRef(value: someObject))

Thus, the collection holds weak references, and objects can be deallocated when there are no more strong references to them.