Learn Swift

Declare values with let and var, rely on type inference, and use Swift's basic types.

Build strings with interpolation and multi-line literals, and understand that Swift strings are Unicode-correct.

Branch with if and switch, loop with for-in, while and ranges, and exit early with guard.

Represent missing values with Optional, and unwrap them safely with if let, guard let, ?? and optional chaining.

Store values in Array, Dictionary and Set, and transform them with map, filter and reduce.

Define functions with argument labels, default values, variadic and inout parameters, and multiple returns via tuples.

Write closure expressions, use trailing-closure and shorthand syntax, and understand capture and @escaping.

Model data with structs: stored properties, memberwise initializers, methods and mutating.

Use classes for shared, identity-bearing objects: initializers, inheritance, overrides and the === operator.

Define enums with raw values, associated values and methods, and match them exhaustively with switch.

Use computed properties, lazy properties, property observers and access control on setters.

Define protocols with property and method requirements, conform types to them, and add default implementations.

Add methods, computed properties, initializers and protocol conformances to existing types with extensions.

Write generic functions and types, constrain type parameters with protocols and where clauses, and use associated types.

Choose between opaque types (some P) and existential types (any P) and understand their cost and limits.

Write property wrappers to reuse property logic, and understand result builders behind SwiftUI's view syntax.

Throw and handle errors with do/catch, try?, try!, typed throws and the Result type.

Encode and decode JSON with Codable, JSONEncoder and JSONDecoder, CodingKeys and decoding strategies.

Structure code into modules with Swift Package Manager, control visibility with access levels, and test with Swift Testing.

Call and write async functions, start work from synchronous code with Task, and combine async with throws.

Run child tasks in parallel with async let and task groups, and make long work respond to cancellation.

Protect mutable state with actors, run UI code on @MainActor, and understand actor reentrancy.

Understand Sendable, how the Swift 6 language mode rejects data races at compile time, and how to fix common errors.

Reason about isolation inheritance, region-based isolation, the sending keyword and how async functions choose where to run.

See how automatic reference counting frees class instances, and break retain cycles with weak and unowned references.

Implement copy-on-write for your own value types and avoid accidental copies, retain/release traffic and existential overhead.

Use ~Copyable types to model unique resources, and control ownership with borrowing, consuming and consume.

Use freestanding and attached macros, understand how they expand at compile time, and know what writing one involves.