iOS Test Assessment

This project is an iOS application designed to fetch and display posts from a remote server using the https://jsonplaceholder.typicode.com/posts API. The app demonstrates key concepts in iOS development, including networking, table views, view models, and efficient data handling with caching.

Features

Fetches and displays posts from the JSONPlaceholder API.
Implements a table view to display posts and a loading indicator for pagination.
Uses a view model (PostViewModel) to manage the data and business logic.
Optimizes heavy computations and caches results to improve performance.
Provides a detail view for individual posts.
Includes unit tests for key components.

Project Structure

MainViewController.swift: Manages the main interface of the app, displaying the list of posts.
PostViewModel.swift: Handles data fetching and business logic for posts.
NetworkManager.swift: Manages network requests to fetch posts.
DetailViewController.swift: Displays detailed information about a selected post.
ComputationCache.swift: Caches computation results to optimize performance.
Constants.swift: Stores constants used throughout the project.
UITableView+Extensions.swift: Adds table view cell registration extension.

Getting Started

Prerequisites

Xcode 12.0 or later
iOS 14.0 or later

Installation

Clone the repository:

git clone https://github.com/your-username/ios-test-assessment.git
cd ios-test-assessment

Open the project in Xcode:
```
open IOS\ Test\ Assessment.xcodeproj
```
Build and run the project on your preferred simulator or device.

Usage

MainViewController

The main view controller manages the list of posts. It uses the PostViewModel to fetch data and update the table view.

PostViewModel

The view model fetches posts from the NetworkManager and updates the UI through a callback. It handles pagination and ensures that data is not fetched multiple times simultaneously.

NetworkManager

The network manager fetches posts from the JSONPlaceholder API. It handles network requests and JSON decoding.

DetailViewController

The detail view controller displays detailed information about a selected post. It uses memoization to avoid redundant computations and re-rendering.

ComputationCache

The computation cache stores results of heavy computations to improve performance. It uses NSCache for efficient in-memory storage.

Unit Tests

The project includes unit tests for the PostViewModel and NetworkManager classes. These tests ensure that data fetching, error handling, and pagination work as expected.

To run the tests, open the project in Xcode and select Product > Test or press Cmd+U.

Documentation

Inline documentation and comments are provided throughout the codebase to explain the purpose and functionality of each component. Here's an example of the performHeavyComputation method documentation:

/// Performs a heavy computation for a given post ID and caches the result to avoid re-computation.
///
/// This method checks if the computation result for the given post ID is already cached. If the result
/// is cached, it uses the cached result. Otherwise, it performs the heavy computation, caches the result,
/// and logs the time taken for the computation.
///
/// - Parameter postId: The ID of the post for which the heavy computation is performed.
private func performHeavyComputation(for postId: Int) {
    // Check if the result is already cached
    if let cachedResult = computationCache[postId] {
        // Use the cached result
        print("Computation result (cached): \(cachedResult)")
        return
    }

    // Start timing the computation
    let startTime = CFAbsoluteTimeGetCurrent()

    // Perform some heavy computation
    var result = 0
    for i in 0..<10000 {
        result += i
    }

    // End timing the computation
    let timeElapsed = CFAbsoluteTimeGetCurrent() - startTime
    print("Time taken for heavy computation: \(timeElapsed) seconds")

    // Create the computation result string
    let computationResult = "Computation result for \(postId): \(result)"

    // Cache the result
    computationCache[postId] = computationResult

    // Log the computation result
    print("Computation result (new): \(computationResult)")
}

Contributing

Contributions are welcome! Please fork the repository and submit a pull request with your changes. Make sure to include tests for any new features or bug fixes.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Acknowledgments

JSONPlaceholder for providing a free API for testing and prototyping.
The Swift community for their valuable resources and support.

itrunks / IOS-Test-Assessment