Question: What Are IOS Protocols?

Why protocols are needed in Swift?

Protocols are used to define a “blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality.” …

Protocols allow developers to write flexible and extensible code in Swift without having to compromise the language’s expressiveness..

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.

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 UIViewController in iOS?

Overview. The UIViewController class defines the shared behavior that is common to all view controllers. You rarely create instances of the UIViewController class directly. Instead, you subclass UIViewController and add the methods and properties needed to manage the view controller’s view hierarchy.

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 formal and informal protocol in iOS?

An informal protocol is a category on NSObject, which implicitly makes almost all objects adopters of the protocol. … A formal protocol declares a list of methods that client classes are expected to implement. Formal protocols have their own declaration, adoption, and type-checking syntax.

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.

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.

Should delegates be weak or strong?

Delegates should always generally be weak.

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 delegates and protocols in iOS?

Delegates are a use of the language feature of protocols. The delegation design pattern is a way of designing your code to use protocols where necessary. In the Cocoa frameworks, the delegate design pattern is used to specify an instance of a class which conforms to a particular protocol.

What is protocol in iOS Swift?

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 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 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 delegate methods?

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 a protocol in Objective C?

Objective-C allows you to define protocols, which declare the methods expected to be used for a particular situation. Protocols are implemented in the classes conforming to the protocol. … We have a delegate object that holds the reference of the calling object that implements the protocol.

How do you delegate in Objective C?

Objective C Delegation by ExampleCreate a protocol.Create a delegate property in the class that performs the assigned task.Once the task is complete, delegate property to be used to return the result.Implement the protocol.