What is category and extension in IOS?

Use category when you need to want to add any methods to a class whose source code is not available to you OR you want to break down a class into several files depending on its functionality. Use class extensions when you want to add some required methods to your class outside the main interface file.

What is category in IOS?

A category allow you to add (only) methods to a class by declaring them in an interface file (. h) and defining them in an implementation file (. m), like in a basic Objective-C class. Sadly a category can’t declare additional instance variable for a class.

What is the difference between an extension and a protocol extension?

Protocols let you describe what methods something should have, but don’t provide the code inside. Extensions let you provide the code inside your methods, but only affect one data type – you can’t add the method to lots of types at the same time.

What is the use of extension?

An extension adds features and functions to a browser. It’s created using familiar web-based technologies—HTML, CSS, and JavaScript. It can take advantage of the same web APIs as JavaScript on a web page, but an extension also has access to its own set of JavaScript APIs.

What is extension in Swift?

In Swift, we can add new functionality to existing types. We can achieve this using an extension. We use the extension keyword to declare an extension. For example, // class definition class Temperature { } // extension of Temperature class extension Temperature { // add new methods }

Why do we use extensions in Swift?

Extensions in Swift are super powerful, because they help you organize your code better. You use an extension to add new functionality to an existing class. And they’re especially useful if you don’t have access to the original code of that class!

Where is category in App Store?

On the left menu, select Grow > Store presence > Store settings. In the “App category” section, select an application type and category.

What’s the difference between a protocol and a class in Swift?

You can create objects from classes, whereas protocols are just type definitions. Try to think of protocols as being abstract definitions, whereas classes and structs are real things you can create.

What are Swift extensions?

A Swift extension allows you to add functionality to a type, a class, a struct, an enum, or a protocol. But extensions are more powerful than that.

Why are extensions used in Swift?

What is extension example?

The definition of an extension is an addition such as to a building, an extra phone line connected to the main line or an extra amount of time given to someone to pay a debt. An example of an extension is adding a second story to a single story house. An example of an extension is line two on a business line.

What is lazy in Swift?

A lazy var is a property whose initial value is not calculated until the first time it’s called. It’s part of a family of properties in which we have constant properties, computed properties, and mutable properties.

What is class extension in Swift?

Swift Class Extensions Another way to add new functionality to a Swift class is to use an extension. Extensions can be used to add features such as methods, initializers, computed properties and subscripts to an existing class without the need to create and reference a subclass.

Why do we use extensions?

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

What is an app category?

App Categories

Category	Description
Entertainment	Apps designed to entertain the user. These apps can contain audio, visual, and other types of content.
Games	Apps where the primary interaction is to play a game. Games can be single or multiplayer. A subcategory must be selected for Games.

What are the main categories of application?

Different Categories of Applications

• Gaming Apps. This is the most popular category of apps housing more than 24% apps in the App store.
• Business Apps. These apps are called as productivity apps and are second most demanded app among users.
• Educational Apps.
• Lifestyle Apps.
• 5. Entertainment Apps.
• Utility Apps.
• Travel Apps.

What is the difference between a class extension and a category?

A category is a way to add methods to existing classes. They usually reside in files called “Class+CategoryName.h”, like “NSView+CustomAdditions.h” (and .m, of course). A class extension is a category, except for 2 main differences: The category has no name.

What is the class extension model in X++?

In this article This article describes the new class extension model in X++. Because over-layering is a very intrusive feature, we recommend that you not use it. The alternative to over-layering is extension. Extension lets you extend existing artifacts in a new model.

What is a class extension in Clang?

Class extensions are like anonymous categories, except that the methods they declare must be implemented in the main @implementation block for the corresponding class. Using the Clang/LLVM 2.0 compiler, you can also declare properties and instance variables in a class extension.

Why are class extensions called Anonymous categories?

Because no name is given in the parentheses, class extensions are often referred to as anonymous categories. Unlike regular categories, a class extension can add its own properties and instance variables to a class. If you declare a property in a class extension, like this: