Table of Contents
When should you use unowned or weak?
Use a weak reference whenever it is valid for that reference to become nil at some point during its lifetime. Conversely, use an unowned reference when you know that the reference will never be nil once it has been set during initialization.
What is a weak reference in Swift?
Weak References. A weak reference is a reference that doesn’t keep a strong hold on the instance it refers to, and so doesn’t stop ARC from disposing of the referenced instance. This behavior prevents the reference from becoming part of a strong reference cycle.
What is the difference between strong and weak references in Swift?
A strong reference means that you want to “own” the object you are referencing with this property/variable. In contrast, with a weak reference you signify that you don’t want to have control over the object’s lifetime.
Why delegates are weak in Swift?
Why delegate should be weak var? Before you begin I highly recommend you to check ARC story. We will design protocol and classes in order to show retain cycle on delegates. With using lazy keyword we are not initializing delegate which means there is no memory leak right now.
How do you use weak?
“Use a weak reference whenever it is valid for that reference to become nil at some point during its lifetime. Conversely, use an unowned reference when you know that the reference will never be nil once it has been set during initialization.”
What is the difference between strong and weak references?
strong is the default. An object remains “alive” as long as there is a strong pointer to it. weak specifies a reference that does not keep the referenced object alive. A weak reference is set to nil when there are no strong references to the object.
What is a weak reference and how could it be useful to us?
Weak reference objects, which do not prevent their referents from being made finalizable, finalized, and then reclaimed. Weak references are most often used to implement canonicalizing mappings. Suppose that the garbage collector determines at a certain point in time that an object is weakly reachable.
Why should delegates be weak?
The reason that objects weakly retain their delegates is to avoid retain cycles. Imagine the following scenario: object a creates b and retains it, then sets itself as b ‘s delegate. a is released by its owner, leaving a retain cycle containing a and b . This is actually a very common scenario.
What is retain cycle in Swift?
What are retain cycles and memory leaks? A memory leak in iOS is when an amount of allocated space in memory cannot be deallocated due to retain cycles. Since Swift uses Automatic Reference Counting (ARC), a retain cycle occurs when two or more objects hold strong references to each other.