Why Delegates Are Weak In Swift?

What is difference between weak and strong 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.

A weak reference is like observing the tree from afar.


What is delegate method?

A delegate method is a method that the delegate object is expected to implement. … A delegate is simply a reference to another object and a delegate method is a method of the delegate. A delegate method implements the callback mechanism which usually takes the sender as one of the parameter to be called.

What is data source in Swift?

To manage the data, you provide the table with a data source object—that is, an object that implements the UITableViewDataSource protocol. A data source object responds to data-related requests from the table. It also manages the table’s data directly, or coordinates with other parts of your app to manage that data.

Why we use delegates in Swift?

Delegation is used for everything from handling table view events using UITableViewDelegate , to modifying cache behavior using NSCacheDelegate . The core purpose of the delegate pattern is to allow an object to communicate back to its owner in a decoupled way.

What is unowned in Swift?

Swift version: 5.2. Unowned variables are similar to weak variables in that they provide a way to reference data without having ownership. However, weak variables can become nil – they are effectively optional.

What is delegate and datasource in Swift?

A data source is an outlet held by NSView and UIView objects such as table views and outline views that require a source from which to populate their rows of visible data. The data source for a view is usually the same object that acts as its delegate, but it can be any object.

How do you call a delegate in Swift?

Key Steps to DelegationCreate a delegate protocol that defines the messages sent to the delegate.Create a delegate property in the delegating class to keep track of the delegate.Adopt and implement the delegate protocol in the delegate class.Call the delegate from the delegating object.Nov 9, 2015

Should delegates be weak or strong?

Delegates should always generally be weak.

What is difference between delegate and datasource in iOS?

A data source is almost identical to a delegate. The difference is in the relationship with the delegating object. Instead of being delegated control of the user interface, a data source is delegated control of data.

How do delegates work in Swift?

A delegate is an object that acts on behalf of, or in coordination with, another object when that object encounters an event in a program. The delegating object is often a responder object–that is, an object inheriting from NSResponder in AppKit or UIResponder in UIKit–that is responding to a user event.

What is Delegates in iOS?

Delegate is simply just a means of communication between objects of iOS applications. You can think delegation as a simple way of connecting objects and communicate with each other. In other words we can say that delegate allows one object to send message to other object when any event occurs.

What is datasource in Swift?

The object that acts as the data source of the table view. Availability.

What are swift delegates?

Delegates are a design pattern that allows one object to send messages to another object when a specific event happens. … Imagine an object A calls an object B to perform an action.

What is weak keyword in Swift?

A weak reference is just a pointer to an object that doesn’t protect the object from being deallocated by ARC. In Swift, all weak references are non-constant Optionals (think var vs. … let ) because the reference can and will be mutated to nil when there is no longer anything holding a strong reference to it.

What is difference between protocol and delegate in Swift?

Protocol is a set of methods (either optional or required) that would be implemented by the class which conforms to that protocol. While, delegate is the reference to that class which conforms to that protocol and will adhere to implement methods defined in protocol. Have a look at this Apple doc for more detail.

What is optional in Swift?

An optional in Swift is basically a constant or variable that can hold a value OR no value. The value can or cannot be nil. It is denoted by appending a “?” after the type declaration. … This is a big impact on the language Swift itself because what that means is that anything non-optional types can never be nil.

What is delegate and protocol in iOS?

Protocols are a way to specify a set of methods you want a class to implement if it wants to work with one of your classes. Delegates and Data Sources like UITableViewDelegate and UITableViewDataSource are protocols indeed. … You can also declare some optional methods by declaring them after the @optional specifier.

Why delegates are weak iOS?

For delegation patters in iOS, the delegated object is the parent, because there is no need for the delegate caller to exist without the delegated object. … When you define a delegate object as property, it’s used a weak reference in the object it is defined in(lets say A, i.e. the delegate object is a property of A).