Swift Patterns

A curated collection of idiomatic design & application patterns for Swift language.

Creational Patterns

Pattern	Description	Status
Abstract Factory	Provides an interface for creating families of releated objects	✔
Builder	Builds a complex object using simple objects	✘
Factory Method	Defers instantiation of an object to a specialized function for creating instances	✔
Object Pool	Instantiates and maintains a group of objects instances of the same type	✘
Singleton	Restricts instantiation of a type to one object	✔

Structural Patterns

Pattern	Description	Status
Bridge	Decouples an interface from its implementation so that the two can vary independently	✘
Composite	Encapsulates and provides access to a number of different objects	✘
Decorator	Adds behavior to an object, statically or dynamically	✘
Facade	Uses one type as an API to a number of others	✘
Flyweight	Reuses existing instances of objects with similar/identical state to minimize resource usage	✘
Proxy	Provides a surrogate for an object to control it's actions	✘

Behavioral Patterns

Pattern	Description	Status
Chain of Responsibility	Avoids coupling a sender to receiver by giving more than object a chance to handle the request	✘
Command	Bundles a command and arguments to call later	✘
Mediator	Connects objects and acts as a proxy	✘
Memento	Generate an opaque token that can be used to go back to a previous state	✘
Observer	Provide a callback for notification of events/changes to data	✘
Registry	Keep track of all subclasses of a given class	✘
State	Encapsulates varying behavior for the same object based on its internal state	✘
Strategy	Enables an algorithm's behavior to be selected at runtime	✘
Template	Defines a skeleton class which defers some methods to subclasses	✘
Visitor	Separates an algorithm from an object on which it operates	✘

Synchronization Patterns

Pattern	Description	Status
Condition Variable	Provides a mechanism for threads to temporarily give up access in order to wait for some condition	✘
Lock/Mutex	Enforces mutual exclusion limit on a resource to gain exclusive access	✘
Monitor	Combination of mutex and condition variable patterns	✘
Read-Write Lock	Allows parallel read access, but only exclusive access on write operations to a resource	✘
Semaphore	Allows controlling access to a common resource	✘

Concurrency Patterns

Pattern	Description	Status
N-Barrier	Prevents a process from proceeding until all N processes reach to the barrier	✘
Bounded Parallelism	Completes large number of independent tasks with resource limits	✘
Broadcast	Transfers a message to all recipients simultaneously	✘
Coroutines	Subroutines that allow suspending and resuming execution at certain locations	✘
Generators	Yields a sequence of values one at a time	✘
Reactor	Demultiplexes service requests delivered concurrently to a service handler and dispatches them syncronously to the associated request handlers	✘
Parallelism	Completes large number of independent tasks	✘
Producer Consumer	Separates tasks from task executions	✘

Messaging Patterns

Pattern	Description	Status
Fan-In	Funnels tasks to a work sink (e.g. server)	✘
Fan-Out	Distributes tasks among workers (e.g. producer)	✘
Futures & Promises	Acts as a place-holder of a result that is initially unknown for synchronization purposes	✘
Publish/Subscribe	Passes information to a collection of recipients who subscribed to a topic	✘
Push & Pull	Distributes messages to multiple workers, arranged in a pipeline	✘

Stability Patterns

Pattern	Description	Status
Bulkheads	Enforces a principle of failure containment (i.e. prevents cascading failures)	✘
Circuit-Breaker	Stops the flow of the requests when requests are likely to fail	✘
Deadline	Allows clients to stop waiting for a response once the probability of response becomes low (e.g. after waiting 10 seconds for a page refresh)	✘
Fail-Fast	Checks the availability of required resources at the start of a request and fails if the requirements are not satisfied	✘
Handshaking	Asks a component if it can take any more load, if it can't, the request is declined	✘
Steady-State	For every service that accumulates a resource, some other service must recycle that resource	✘

Profiling Patterns

Pattern	Description	Status
Timing Functions	Wraps a function and logs the execution	✘

Idioms

Pattern	Description	Status
Functional Options	Allows creating clean APIs with sane defaults and idiomatic overrides	✘

Anti-Patterns

Pattern	Description	Status
Cascading Failures	A failure in a system of interconnected parts in which the failure of a part causes a domino effect	✘

Credits

Inspired by:

• @tmrts's go-pattern

Dependencies

• SwiftLint

Support

If you have a question, find a bug, or just want to say hi, please open an issue on GitHub.

If you want to contribute, please read the guide.

License

MIT License © Islam Temirbek