What Is Optional Methods In Swift Protocol?

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 are protocols in Swift?

Protocols are used to define a “blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality.” Swift checks for protocol conformity issues at compile-time, allowing developers to discover some fatal bugs in the code even before running the program.

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

CAN protocols have properties?

A protocol can have properties as well as methods that a class, enum or struct conforming to this protocol can implement. A protocol declaration only specifies the required property name and type. It doesn’t say anything about whether the property should be a stored one or a computed one.

What is unowned self in Swift?

The most common place you’ll see unowned variables is with closures that declare [unowned self] – this means “I want to reference self inside this closure but I don’t want to own it.” Why unowned rather than weak ? Both would work, but let’s face it: if self is nil inside a closure, something has gone wrong!

What is datasource in Swift?

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

What is delegate method in Swift?

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.

Why is delegate weak in 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).

What is a retain cycle 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.

How do I create a custom delegate in Swift?

How To Create A Custom Delegate In SwiftThe Delegate Pattern in Swift.Create A Delegate Protocol.Extend A Delegate Protocol.Implement A Custom Delegate.How To Use A Custom Delegate.Creating Optional Delegate Methods.Jan 3, 2021

What are extensions in Swift?

Extensions add new functionality to an existing class, structure, enumeration, or protocol type. This includes the ability to extend types for which you don’t have access to the original source code (known as retroactive modeling). Extensions are similar to categories in Objective-C.

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.

How do I override a swift extension?

It is not possible to override functionality (like properties or methods) in extensions as documented in Apple’s Swift Guide. Extensions can add new functionality to a type, but they cannot override existing functionality. The compiler is allowing you to override in the extension for compatibility with Objective-C.

Can you extend a struct Swift?

Swift extensions are similar to categories in Objective-C, and can be used to extend a class, struct, enum, or protocol. Swift extensions can be used to add new initializers, methods, computed properties, and nested types. You can even use them to provide default implementations for protocol methods.

How do you use protocols?

A protocol defines a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. The protocol can then be adopted by a class, structure, or enumeration to provide an actual implementation of those requirements.

What are the different types of Swift messages?

SWIFT groups message types into the following categories:Customer Payments and Cheques.Financial Institution Transfers.Treasury Markets: Foreign Exchange and Derivatives.Collections and Cash Letters.Securities Markets.Treasury Markets: Precious Metals and Syndications.Documentary Credits and Guarantees.More items…

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.

Why delegates are weak in Swift?

With using lazy keyword we are not initializing delegate which means there is no memory leak right now. Let’s break that. Object will be created and there will be memory leak. … Therefore, if the object conforming to the protocol needs to be stored in a weak property then the protocol must be a class-only protocol.

What is lazy in Swift?

Swift has a mechanism built right into the language that enables just-in-time calculation of expensive work, and it is called a lazy variable. These variables are created using a function you specify only when that variable is first requested.

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.

What are IOS protocols?

A protocol defines a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. The protocol can then be adopted by a class, structure, or enumeration to provide an actual implementation of those requirements.