Interview Questions
Type casting in class hierarchies involves: 1) Using 'is' for type checking, 2) 'as?' for conditional downcasting, 3) 'as!' for forced downcasting, 4) 'as' for upcasting, 5) Type casting patterns in switch statements, 6) Handling inheritance relationships, 7) Protocol conformance checking, 8) Runtime type determination.
Nested types in Swift: 1) Define types within other types, 2) Provide namespace scoping, 3) Support access control relationships, 4) Enable related type grouping, 5) Support generic type constraints, 6) Allow internal implementation hiding, 7) Improve code organization, 8) Support builder pattern implementation.
Observer pattern implementation includes: 1) Using delegation, 2) NotificationCenter usage, 3) Key-Value Observing (KVO), 4) Custom observer protocols, 5) Combine framework integration, 6) Weak reference handling, 7) Event broadcasting mechanisms, 8) Memory management considerations.
Convenience initializers: 1) Provide alternative initialization patterns, 2) Must call designated initializer, 3) Support initialization abstraction, 4) Reduce code duplication, 5) Enable default parameter values, 6) Support initialization delegation, 7) Improve initialization readability, 8) Maintain initialization safety.
Composition vs Inheritance considerations: 1) Favor composition over inheritance, 2) Use protocols for shared behavior, 3) Implement delegation patterns, 4) Consider value type composition, 5) Use generic constraints, 6) Implement dependency injection, 7) Handle state sharing, 8) Manage object lifecycle.
Factory method patterns include: 1) Static factory methods, 2) Factory protocol implementation, 3) Generic factory methods, 4) Abstract factory pattern, 5) Factory method inheritance, 6) Dependency injection support, 7) Error handling in factories, 8) Configuration-based creation.
Key differences include: 1) Classes are reference types while structures are value types, 2) Classes support inheritance while structures don't, 3) Classes have deinitializers, structures don't, 4) Classes allow reference counting with ARC, 5) Structures automatically get a memberwise initializer, 6) Classes can participate in type casting, 7) Structures are preferred for data models in Swift for better performance and thread safety, 8) Classes are better for shared resources and when identity is important.
Swift inheritance features include: 1) Single inheritance only (no multiple inheritance), 2) Method overriding using 'override' keyword, 3) Preventing overrides with 'final' keyword, 4) Super class initialization requirements, 5) Property override rules, 6) Access control in inheritance hierarchy, 7) Protocol inheritance is allowed and can be multiple, 8) Required initializers in subclasses. Limitations include no multiple class inheritance and strict initialization rules.
Type methods and properties belong to the type itself: 1) Declared using 'static' or 'class' keywords, 2) 'static' prevents override in subclasses, 3) 'class' allows override in subclasses, 4) Can access other type properties and methods, 5) Cannot access instance methods or properties directly, 6) Useful for utility functions and shared resources, 7) Support computed and stored properties, 8) Thread-safe by default.
Swift supports polymorphism through: 1) Inheritance-based method overriding, 2) Protocol conformance for interface polymorphism, 3) Generic type parameters, 4) Type casting and runtime checks, 5) Dynamic dispatch for class methods, 6) Static dispatch optimization when possible, 7) Protocol extensions for default implementations, 8) Associated types in protocols for type relationships.
Initializers in Swift classes serve multiple purposes: 1) Designated initializers as primary initializers, 2) Convenience initializers for initialization shortcuts, 3) Required initializers that must be implemented by subclasses, 4) Failable initializers that might return nil, 5) Two-phase initialization process, 6) Initializer inheritance rules, 7) Super class initialization requirements, 8) Automatic initializer inheritance conditions.
Deinitializers in Swift: 1) Declared using 'deinit' keyword, 2) Called automatically when object is deallocated, 3) Only available in classes, not structures, 4) Cannot be called directly, 5) No parameters or parentheses, 6) Used for cleanup operations, 7) Important for resource management, 8) Called in reverse order of initialization for inheritance hierarchies.
Computed properties: 1) Calculate value dynamically rather than storing it, 2) Can have getter and optional setter, 3) Useful for derived values, 4) Cannot use property observers, 5) Can be overridden in subclasses, 6) Support access control, 7) Can depend on other properties, 8) Useful for encapsulation and maintaining consistency. They're ideal when a property's value depends on other properties.
Method dispatch in Swift classes involves: 1) Dynamic dispatch by default for instance methods, 2) Static dispatch for final methods, 3) Table dispatch for protocol methods, 4) Message dispatch for @objc methods, 5) Dispatch optimization by compiler, 6) Override table maintenance, 7) Performance implications of different dispatch types, 8) Direct dispatch for private methods.
Access control provides: 1) Encapsulation of implementation details, 2) Interface-based programming, 3) Five access levels (open, public, internal, fileprivate, private), 4) Module-level boundaries, 5) Subclass and override control, 6) Property getter/setter control, 7) Protocol conformance requirements, 8) Framework API design control. It's crucial for maintaining proper encapsulation and API design.
Reference cycle management includes: 1) Using weak references for optional references, 2) Unowned references for non-optional references, 3) Closure capture lists, 4) Parent-child relationship considerations, 5) Delegate pattern implementation, 6) Property observer cleanup, 7) Deinitializer usage, 8) ARC (Automatic Reference Counting) understanding.
Property wrappers provide: 1) Reusable property behavior encapsulation, 2) Separation of concerns in property implementation, 3) Custom getter/setter logic, 4) State management patterns, 5) Validation and transformation logic, 6) Thread safety implementation, 7) Dependency injection patterns, 8) Observable property patterns.
Singleton implementation includes: 1) Static shared instance property, 2) Private initializer to prevent external creation, 3) Thread-safety considerations, 4) Lazy initialization support, 5) Property wrapper usage for singletons, 6) Testing considerations, 7) Dependency injection alternatives, 8) Access control implementation.
The 'final' keyword: 1) Prevents method overriding in subclasses, 2) Prevents class inheritance, 3) Enables compiler optimizations, 4) Improves method dispatch performance, 5) Helps maintain API contract, 6) Supports design by contract, 7) Reduces runtime overhead, 8) Important for framework design.
Method overloading allows: 1) Multiple methods with same name but different parameters, 2) Return type differentiation, 3) Generic type constraints, 4) Parameter label variations, 5) Default parameter values, 6) Type-specific implementations, 7) Operator overloading, 8) Protocol requirement satisfaction.
Inheritance best practices include: 1) Favoring composition over inheritance, 2) Using protocols for shared behavior, 3) Keeping inheritance hierarchies shallow, 4) Documenting inheritance requirements, 5) Proper use of override keyword, 6) Access control consideration, 7) Initialization pattern implementation, 8) Memory management awareness.
Decorator pattern implementation includes: 1) Protocol-based interface definition, 2) Base class implementation, 3) Decorator class hierarchy, 4) Composition over inheritance, 5) Dynamic behavior addition, 6) Property forwarding, 7) Method delegation, 8) Stack-based decoration.
Dependency injection practices include: 1) Constructor injection, 2) Property injection, 3) Method injection, 4) Protocol-based dependencies, 5) Container management, 6) Scope management, 7) Testing considerations, 8) Circular dependency prevention.
Class cluster implementation involves: 1) Abstract factory pattern usage, 2) Private subclass creation, 3) Public interface definition, 4) Factory method implementation, 5) Type-specific optimization, 6) Initialization pattern design, 7) Inheritance hierarchy management, 8) API simplification.
Builder pattern implementation includes: 1) Method chaining support, 2) Default value handling, 3) Validation logic, 4) Immutable object creation, 5) Complex object construction, 6) Optional parameter management, 7) Fluent interface design, 8) Result builder integration.
Thread-safe implementation includes: 1) Serial queue usage, 2) Property wrapper implementation, 3) Atomic operations, 4) Lock mechanisms, 5) Barrier flags, 6) Read-write synchronization, 7) Thread-safe property access, 8) Concurrent queue management.