Quick Answer: What Is Delegate And Datasource In Swift?

What is dequeueReusableCell in Swift?

dequeueReusableCell(withIdentifier:) Returns a reusable table-view cell object located by its identifier.

Availability.

Declaration.

Parameters.

Return Value..

What is a delegate in Swift?

Swift version: 5.2. Delegates are extremely common in iOS development, but fortunately they are easy to understand: a delegate is any object that should be notified when something interesting has happened.

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 reuseIdentifier in Swift?

As per the Apple’s doc – reuseIdentifier is a string used to identify the cell object if it is to be reused for drawing multiple rows of a table view. Pass nil if the cell object is not to be reused. You should use the same reuse identifier for all cells of the same form. –

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.

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 is delegate in xcode?

A delegate is an object that another class can pass messages to. … Delegate protocols exist so that you can make sure that the delegate object has the necessary methods to deal with your messages. Methods in a delegate protocol can be @optional or enforced. Any methods that are optional don’t have to be defined.

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 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.

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 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 interface in Swift?

2. 17. Instead of interface swift have 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.

How can we use a reusable cell in Uitableview?

The right way to do this is to configure the prepareForReuse() method inside the NewsCell class. This method is called whenever a tableView dequeues a cell. So any cached data should be cleared here or it will persist in the dequeued cell unless you manually change it before returning it in the cellForRowAt method.

What is datasource in Swift?

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

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 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 is a delegate in IOS?

Delegation is a simple and powerful pattern in which one object in a program acts on behalf of, or in coordination with, another object. The delegating object keeps a reference to the other object—the delegate—and at the appropriate time sends a message to it.

What is delegate in iOS with example?

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 Swift is called protocol oriented language?

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.

How do you stop reusing cells in Uitableview?

4 Answers. Try to implement prepareForReuse method in your custom cell and set all fields text to nil. You shouldn’t prevent that, but if you really want to, I think that not setting cell identifier to your UITableViewCell should do the trick.