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Dependency Injection in Swift

Dependency injection could also be a fundamental pattern that’s very easy to adopt. Dependency Injection (DI) in Swift, as in other programming languages, is a technique for achieving Inversion of Control (IoC) by externalizing the construction and setting of dependencies of an object.

Swift Dependency injection means giving an object it’s instance variables. Dependency injection is nothing more injecting dependencies into an object instead of tasking the thing with the responsibility of making its dependencies or as DM sure put it you give an object its instance variables rather than creating them within the thing.

What does one Gain?

Beginners could also be wondering what they gain by using dependency injection. Here is a list of the advantages of dependency injection.

Transparency

    By injecting the dependencies of an object, the responsibilities and requirements of a category or structure become clearer and more transparent.

    By injecting an invitation manager into a view controller, we understand that a view controller dependence on the request manager and that we can assume that a view controller is liable for request managing or handling.

    Testing:

    Unit testing is such very easier with dependency injection. Dependency injection makes it very easy to exchange an object dependency with mock objects making units tests easier to line up an isolated behaviour.

    Separation of Concerns:

    Dependency injection promotes the separation of concerns by reducing the coupling between components. Each component focuses on its specific task, enhancing maintainability and scalability.

    Coupling Reduction:

    Dependency injection helps in reducing tight coupling between classes, which enhances flexibility, promotes reusability, and makes the software easier to maintain and extend.

    Types of Swift Dependency Injection

    Initializer Injection:

    Dependencies are provided through a class constructor or structure.

    Example

    class DataService {
    private let networkManager: NetworkManager

    init(networkManager: NetworkManager) {
        self.networkManager = networkManager
    }

    // Use networkManager in other methods
}

// Usage
let networkManager = NetworkManager()
let dataService = DataService(networkManager: networkManager)
    Swift

    Property Injection:

    Dependencies are set through public properties of the class.

    Example:

    class DataService {
    var networkManager: NetworkManager?

    // Other methods can use networkManager
}

// Usage
let dataService = DataService()
dataService.networkManager = NetworkManager()
    Swift

    Method Injection:

    Dependencies are provided through methods of the class.

    Example:

    class DataService {
    func fetchData(using networkManager: NetworkManager) {
        // Use networkManager to fetch data
    }
}

// Usage
let dataService = DataService()
let networkManager = NetworkManager()
dataService.fetchData(using: networkManager)
    Swift

    Frameworks and Libraries for Dependency Injection:

    • Swinject: A lightweight dependency injection framework for Swift.
    • Dip: Dip is a dependency injection container framework for Swift.
    • Cleanse: A lightweight dependency injection framework compatible with Swift and Objective-C.

    Author: TCF Editorial
    Copyright The Cloudflare.

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