The == operator checks if the values of two instances are equal, while the === operator checks if two instances refer to the same object instance in memory.

Optionals in Swift are variables that can hold either a value or nil, indicating the absence of a value. They are declared using a question mark (?) after the type.

Combine is a framework that lets you process asynchronous values over time. It uses publishers and subscribers to manage data streams, and it's often used with SwiftUI for reactive programming.

In Swift, use let to declare constants (immutable values) and var to declare variables (mutable values). This helps enforce safer and more predictable code.

The defer statement in Swift is used to schedule a block of code to be executed just before the current scope exits, regardless of how the scope is exited, ensuring that resources are cleaned up properly. 

A Swift playground is an interactive environment in Xcode that lets you write Swift code and see the results immediately. It's ideal for learning Swift or testing code snippets quickly.

You can use the enumerated() method to iterate over a collection with both index and element:​

for (index, element) in collection.enumerated() {
    // Use index and element
}

Lazy properties in Swift are properties whose initial values are not calculated until the first time they are used, which can improve performance by delaying computation until necessary.

Protocols define a blueprint of methods, properties, and other requirements that suit a particular piece of functionality. Classes, structs, and enums can adopt protocols to provide implementations of these requirements.

Swift provides a robust error handling model using do, try, and catch keywords, allowing developers to write safer and more reliable code by handling potential errors gracefully.

Swift offers modern syntax, type safety, and features like optionals, making it more user-friendly and less error-prone compared to Objective-C.

Swift uses Automatic Reference Counting (ARC) to track and manage memory usage, ensuring efficient allocation and deallocation of memory.

Extensions in Swift allow you to add new functionality to existing classes, structs, enums, or protocols without modifying their original source code, promoting code organization and reuse. 

You can handle optional values safely using optional binding (if let or guard let), optional chaining, or the nil-coalescing operator (??) to provide default values.​

The guard statement in Swift is used for early exits in functions or loops. It allows you to handle conditions that must be true for the rest of the code to execute, improving readability and safety. ​

Higher-order functions are functions that take other functions as parameters or return functions as results. Examples in Swift include map, filter, and reduce.

Swift is a powerful and intuitive programming language developed by Apple Inc. for building applications on iOS, macOS, watchOS, and tvOS platforms.

Structs and classes in Swift are both used to create custom data types. The key difference is that structs are value types and copied when assigned, while classes are reference types and passed by reference.

SwiftUI is a modern UI framework by Apple that uses declarative syntax to build user interfaces for all Apple platforms. You write views and layouts with concise code, making development faster and more intuitive.

The typealias keyword in Swift allows you to define a new name for an existing type, improving code readability and making complex type declarations more manageable.

Tuples in Swift allow you to group multiple values into a single compound value. They can hold different types of data and are useful for returning multiple values from a function. ​

Synchronous code runs in sequence, blocking the thread until execution finishes. Asynchronous code in Swift allows tasks to run in the background, improving app responsiveness—often implemented with async/await or GCD.

Closures are self-contained blocks of functionality that can be passed around and used in your code. They can capture and store references to variables and constants from the surrounding context.

Swift supports functional programming paradigms through features like first-class functions, closures, higher-order functions, and immutability, allowing developers to write concise and expressive code. 

Type inference allows Swift to automatically deduce the type of a variable or constant based on the assigned value, reducing the need for explicit type annotations.