Introduction to Business Logic

What is Business Logic?

Business logic is the part of a software application that encodes the real-world business rules that determine how data can be created, stored, and changed. It is the bridge between the raw data and the end-user experience, ensuring that the data adheres to the rules and regulations of the business domain.

Importance of Business Logic in iOS Development

In iOS development, business logic is crucial for creating robust and maintainable applications. It helps in abstracting the core functionality from the user interface, making the app more scalable and easier to test. By separating business logic from other components, developers can focus on individual parts of the application without affecting the entire system.

Components of Business Logic

Business logic is typically composed of the following components:

• Validation: Ensures that the data entered by the user meets the required criteria before processing.
• Business Rules: The rules that define the operations, definitions, and constraints that apply to an organization.
• Data Transformation: Converts data from one format or structure to another.
• Processing: The core logic that manipulates data and performs the necessary operations.

Example: Implementing Business Logic in an iOS App

Let's consider an example where we need to implement business logic to validate user input in an iOS app. We will create a function that checks if a given email address is valid.

func isValidEmail(_ email: String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"
    let emailPred = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
    return emailPred.evaluate(with: email)
}
                

import XCTest
@testable import YourApp

class EmailValidationTests: XCTestCase {

    func testValidEmail() {
        XCTAssertTrue(isValidEmail("test@example.com"))
    }

    func testInvalidEmail() {
        XCTAssertFalse(isValidEmail("test@example"))
        XCTAssertFalse(isValidEmail("test@.com"))
        XCTAssertFalse(isValidEmail("test@com"))
    }
}