Day 1: Introduction to Concurrency in iOS

Session 1: Understanding Concurrency and Multithreading

• What is concurrency, and why is it important in iOS development?
• Difference between synchronous vs. asynchronous execution.
• Overview of main thread vs. background threads.

Session 2: Introduction to Grand Central Dispatch (GCD)

• What is Grand Central Dispatch (GCD)?
• Understanding dispatch queues (serial vs. concurrent).
• Performing basic asynchronous tasks using GCD.

Session 3: Executing Tasks in Background Threads

• Using DispatchQueue.global() and DispatchQueue.main().
• Running CPU-intensive and I/O tasks asynchronously.
• Switching between background and main thread for UI updates.

Day 2: Advanced GCD Concepts

Session 1: Managing Concurrent Tasks with Dispatch Groups

• Introduction to Dispatch Groups.
• Waiting for multiple tasks to complete using notify() and wait().
• Implementing asynchronous dependency management.

Session 2: Synchronization and Thread Safety in GCD

• Understanding race conditions and data corruption.
• Using Dispatch Barriers for thread-safe resource access.
• Implementing Dispatch Semaphores for resource control.

Session 3: Optimizing Task Execution with QoS and Prioritization

• Understanding Quality of Service (QoS) levels in GCD.
• Assigning priorities to tasks for better performance.
• Using concurrent queues with task prioritization.

Day 3: Introduction to Operation Queues

Session 1: Understanding Operation and OperationQueue

• Introduction to NSOperation and NSOperationQueue.
• Differences between GCD and Operation Queues.
• Creating and running simple operations using OperationQueue.

Session 2: Managing Task Dependencies with Operation Queues

• Setting up dependencies between operations.
• Cancelling operations and handling failures.
• Using maxConcurrentOperationCount for controlled execution.

Session 3: Customizing and Subclassing NSOperation

• Creating custom operations by subclassing Operation.
• Implementing asynchronous operations within Operation.
• Using KVO (Key-Value Observing) for operation state tracking.

Day 4: Best Practices for Concurrency and Debugging Issues

Session 1: Handling Background Tasks Efficiently

• Using BackgroundTask API for long-running operations.
• Implementing WorkManager and scheduled tasks.
• Handling low memory and system termination scenarios.

Session 2: Debugging Multithreading Issues in iOS

• Identifying deadlocks, race conditions, and UI freezes.
• Using Xcode’s Thread Debugger to analyze concurrent execution.
• Debugging with Thread Sanitizer and runtime logs.

Session 3: Performance Optimization in Concurrency

• Best practices for minimizing thread overhead.
• Using lazy loading and caching to improve responsiveness.
• Avoiding excessive context switching for optimal performance.

Day 5: Hands-On Project and Real-World Application

Session 1: Implementing Concurrency in a Real-World App

• Designing a multithreaded iOS application.
• Using GCD and OperationQueue for background processing.
• Implementing parallel API calls and data processing.

Session 2: Applying Advanced Concurrency Features

• Combining GCD and OperationQueue for optimized execution.
• Using Combine framework for reactive programming.
• Handling thread-safe database access with Core Data.

Session 3: Best Practices and Final Review

• Structuring concurrent code for scalability and maintainability.
• Reviewing common pitfalls and how to avoid them.
• Final Q&A and discussion on real-world concurrency challenges.