Question: What Are Delegates And Protocols In IOS?

What are 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..

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 protocol give example?

A protocol is a standard set of rules that allow electronic devices to communicate with each other. … Protocols exist for several different applications. Examples include wired networking (e.g., Ethernet), wireless networking (e.g., 802.11ac), and Internet communication (e.g., IP).

What is a delegate class?

A delegate is a type that represents references to methods with a particular parameter list and return type. … Any method from any accessible class or struct that matches the delegate type can be assigned to the delegate. The method can be either static or an instance method.

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 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 is difference between protocol and delegate in iOS?

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 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 I use delegates in Swift?

The basic steps to use delegation are the same for both Objective-C and Swift:Create 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.More items…•Nov 9, 2015

Why Swift is protocol oriented programming?

Swift checks for protocol conformity issues at compile-time, allowing developers to discover some fatal bugs in the code even before running the program. Protocols allow developers to write flexible and extensible code in Swift without having to compromise the language’s expressiveness.

What are delegates in iOS 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 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.

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).

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.

What is GCD in iOS Swift?

Grand Central Dispatch (GCD) is a low-level API for managing concurrent operations. It can help you improve your app’s responsiveness by deferring computationally expensive tasks to the background. It’s an easier concurrency model to work with than locks and threads.