One problem with strong references is caching, particular with very large structures like images. Suppose you have an application which has to work with user-supplied images, like the web site design tool I work on. Naturally you want to cache these images, because loading them from disk is very expensive and you want to avoid … Read more
Using a WeakReference in Android isn’t any different than using one in plain old Java. You should think about using one whenever you need a reference to an object, but you don’t want that reference to protect the object from the garbage collector. A classic example is a cache that you want to be garbage … Read more
Java provides two different types/classes of Reference Objects: strong and weak. Weak Reference Objects can be further divided into soft and phantom. Strong Weak soft phantom Let’s go point by point. Strong Reference Object StringBuilder builder = new StringBuilder(); This is the default type/class of Reference Object, if not differently specified: builder is a strong … Read more
Create a generic wrapper as: class Weak<T: AnyObject> { weak var value : T? init (value: T) { self.value = value } } Add instances of this class to your array. class Stuff {} var weakly : [Weak<Stuff>] = [Weak(value: Stuff()), Weak(value: Stuff())] When defining Weak you can use either struct or class. Also, to … Read more
Both weak and unowned references do not create a strong hold on the referred object (a.k.a. they don’t increase the retain count in order to prevent ARC from deallocating the referred object). But why two keywords? This distinction has to do with the fact that Optional types are built-in the Swift language. Long story short … Read more
It helps not to focus on the strong or weak part of the discussion. Instead focus on the cycle part. A retain cycle is a loop that happens when Object A retains Object B, and Object B retains Object A. In that situation, if either object is released: Object A won’t be deallocated because Object … Read more
From Understanding Weak References, by Ethan Nicholas: Weak references A weak reference, simply put, is a reference that isn’t strong enough to force an object to remain in memory. Weak references allow you to leverage the garbage collector’s ability to determine reachability for you, so you don’t have to do it yourself. You create a … Read more