What is a weak objective?

What is a weak objective?

weak: will assign the incoming value to it without retaining it. So the basic difference is the retaining of the new variable. Generaly you want to retain it but there are situations where you don’t want to have it otherwise you will get a retain cycle and can not free the memory the objects.

What is strong property in Objective-C?

strong (default) Strong just means you have a reference to an object and you will keep that object alive. As long as you hold that reference to the object in that property, that object will not be deallocated and released back into memory.

What is strong reference and weak reference in Objective-C?

Objective-C uses reference counting to manage the memory of its objects through the concept of object ownership. There are two types of object reference: Strong references, which keep an object “alive” in memory. Weak references, which have no effect on the lifetime of a referenced object.

What is a retain cycle?

One example is retain cycles, which occur when two objects reference each other, making it impossible for either to ever get deallocated — because both of their retain counts will always be one or greater.

Why do you generally create a weak reference when using self in a block?

It does ensure self doesn’t get deallocated while executing the block.

What is weak and strong property in IOS?

A weak reference is just a pointer to an object that doesn’t protect the object from being deallocated by ARC. While strong references increase the retain count of an object by 1, weak references do not. In addition, weak references zero out the pointer to your object when it successfully deallocates.

What is weak VAR in Swift?

A weak reference is a reference that does not keep a stronghold on the instance it refers to, and so does not stop ARC from disposing of the referenced instance. This behavior prevents the reference from becoming part of a strong reference cycle.

What is Nonatomic property?

Nonatomic means multiple thread access the variable (dynamic type). Nonatomic is thread unsafe. But it is fast in performance. Nonatomic is NOT default behavior; we need to add nonatomic keyword in property attribute.

What is strong and weak references?

What is the difference between weak and unowned?

The main difference between weak and unowned is that weak is optional while unowned is non-optional. By declaring it weak you get to handle the case that it might be nil inside the closure at some point. If you try to access an unowned variable that happens to be nil, it will crash the whole program.

How are property attributes declared in Objective C?

Property Attributes in Objective-C. In Objective-C, when you declare a property, after you type @property, there are sometimes words in parentheses (strong or weak; copy or retain).

What happens to weak reference in Objective C?

If you have a reference to an object and all of the strong references to it go away and it gets deallocated, your weak reference does not point to some junk memory, which can give you crashes. It will just automatically nil itself out. Then, in Objective-C, you can safely send messages to nil and nothing happens.

What is the difference between strong and weak property attributes?

Strong just means you have a reference to an object and you will keep that object alive. As long as you hold that reference to the object in that property, that object will not be deallocated and released back into memory. Strong’s analog is weak. Weak gives you a reference so you can still “talk” to that object, but you are not keeping it alive.

What’s the difference between a strong object and a weak object?

The default is called strong. Strong just means you have a reference to an object and you will keep that object alive. As long as you hold that reference to the object in that property, that object will not be deallocated and released back into memory. Strong’s analog is weak.