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.
Is delegate a protocol?
Delegation works hand in hand with protocols because it allows a class to specify a delegate property which conforms to some protocol. Then a second class which actually conforms to that protocol can be assigned to that property.
What is iOS delegation pattern?
The core purpose of the delegate pattern is to allow an object to communicate back to its owner in a decoupled way. By not requiring an object to know the concrete type of its owner, we can write code that is much easier to reuse and maintain.
How delegates are implemented in iOS?
To create your own delegate, first you need to create a protocol and declare the necessary methods, without implementing. And then implement this protocol into your header class where you want to implement the delegate or delegate methods. This is the service class where some task should be done.
Can delegation be implemented without a protocol?
You don’t have to use protocols…but you should if you want to keep things flexible. Delegation is in essence asking someone else to do something for you. If you enforce a contract, then its more likely they will do it for you.
What is protocol in Swift iOS?
In Swift, a protocol defines a blueprint of methods or properties that can then be adopted by classes (or any other types).
Can delegation be implemented without protocol if yes then why do we need protocol?
What is difference between delegate and DataSource in Swift?
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 is difference between data source and delegate?
A data source is like a delegate except that, instead of being delegated control of the user interface, it is delegated control of data. 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.
Why do we need protocol 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.
Could you explain what is the difference between delegate and KVO?
KVO is useful to listen “without the class knowing”, although of course that’s not the case, the class on which KVO is applied does not need to be changed. Show activity on this post. Delegation is a design pattern that you use when you want some other object to modify the sender’s behavior.
What is difference between delegate and datasource in IOS?
What is difference between delegate and DataSource in IOS?
What’s the difference between using a delegate and notification?
use delegates when you want the receiving object to influence an action that will happen to the sending object. use notifications when you need to inform multiple objects of an event.
Is it possible to prevent the adoption of a protocol by a struct?
A protocol defines a blueprint of methods, properties, and other requirements. The protocol can then be adopted by a class, structure, or enumeration to provide an actual implementation of those requirements. But there would be a time when you want to restrict protocols to be adopted by a specific class.
What is the difference between a delegate and an Nsnotification?
Delegates, in much the same way, create a link between two objects, and you don’t need to know what type the delegate will be, it simply has to implement the protocol. On the other hand, NSNotifications are like a radio station. They broadcast their message to whoever is willing to listen.
Can you explain KVO and how it’s used on Apple’s platforms?
Key-value observing is a Cocoa programming pattern you use to notify objects about changes to properties of other objects. It’s useful for communicating changes between logically separated parts of your app—such as between models and views. You can only use key-value observing with classes that inherit from NSObject .
What is delegate and datasource in IOS?
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.
How do I use Notification Center in Swift?
First, register an observer for a notification with: addObserver(_:selector:name:object:) Then, post a notification with post(name:object:userInfo:) … … after which your selector is called. And don’t forget to remove the observer with removeObserver()
Can structs conform to protocols?
Structs do not inherit from protocols, they conform to protocols.
What is the difference between delegate and notification in Swift?
Delegate is passing message from one object to other object. It is like one to one communication while nsnotification is like passing message to multiple objects at the same time. All other objects that have subscribed to that notification or acting observers to that notification can or can’t respond to that event.
What is difference between KVC and KVO?
Key-Value-Observing (KVO) allows you to observe changes to a property or value. To observe a property using KVO you would identify to property with a string; i.e., using KVC. Therefore, the observable object must be KVC compliant.
What is the difference between delegate and DataSource?
How do I use protocol and delegate in Swift 4?
Key Steps to Delegation
- 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.
- Call the delegate from the delegating object.
What is the difference between a protocol and a delegate?
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. Show activity on this post.
What are protocols and delegates in Objective-C?
Protocols and delegates are not restricted only to Objective-C and Mac/iOS development, but the Objective-C language and the Apple frameworks make heavy use of this awesome language feature and design pattern. Here’s an example. In the UIKit framework of Cocoa Touch, there is a UITextFieldDelegate protocol.
Where does the delegate protocol live?
The delegate protocol, in general, lives with the delegate property since it is someone else who will be the delegate. It is the other class that is going to conform to the protocol. Where to place the protocol? Place the protocol with the delegate property. The protocol goes with the property.
What is the use of delegate pattern?
It is a design pattern in which an object called the delegate acts on behalf of, and at the request of, another object. At some point in execution, it sends a message to its delegate; the message tells the delegate that some event is about to happen and asks for some response.