Copyright (c) 2025 Cong Le. All Rights Reserved.
These notes cover a wide array of subjects with varying levels of depth and detail. I aim to present iOS development concepts and practices using visual representations.
Below is a sample of note in this repo.
---
title: Design Patterns in Mixed Languages
config:
layout: elk
look: handDrawn
theme: dark
---
%%{
init: {
'fontFamily': 'verdana',
'themeVariables': {
'primaryColor': '#BB2528',
'primaryTextColor': '#f529',
'primaryBorderColor': '#7C0000',
'lineColor': '#F8B229',
'secondaryColor': '#006100',
'tertiaryColor': '#fff'
}
}
}%%
graph LR
A[Identify the core<br>problem] --> B{Is the<br>problem<br>related to}
B -- Creating objects --> C(Creational)
B -- Assembling objects --> D(Structural)
B -- Object interactions/<br>responsibilities --> E(Behavioral)
B -- Managing memory/resources --> M(Memory Management)
subgraph Creational_Patterns["Creational Patterns"]
direction LR
C --> CR1[Need single instance<br>per app/module] --> S(Singleton)
C --> CR2[Decouple object creation<br>from usage] --> FM(Factory Method)
C --> CR3[Create families of<br>related objects] --> AF(Abstract Factory)
C --> CR4[Create duplicate objects<br>efficiently] --> P(Prototype)
C --> CR5[Construct complex objects<br>step by step] --> BLD(Builder)
C --> CR6[Create objects based on<br> runtime parameters] --> BO(Builder with Options)
end
subgraph Structural_Patterns["Structural Patterns"]
direction LR
D --> ST1[Simplify complex<br>subsystems] --> F(Facade);
D --> ST2["Make incompatible interfaces<br>compatible<br>(Swift/ObjC/C++)"] --> AD(Adapter);
D --> ST3["Represent part-whole<br>hierarchies<br>(Views)"] --> CP(Composite);
D --> ST4["Control access to objects<br>(Network, Files)"] --> PR(Proxy);
D --> ST5["Dynamically add/remove<br>behavior<br>(at runtime)"] --> DC(Decorator);
D --> ST6[Decouple abstraction from<br>implementation] --> BR(Bridge);
D --> ST7[Efficiently share large numbers<br>of fine-grained objects] --> FW(Flyweight);
D --> ST8[Combine multiple objects<br>into a single interface] --> AGG(Aggregator);
end
subgraph Behavioral_Patterns["Behavioral Patterns"]
direction LR
E --> BH1["Define a family of<br>algorithms<br>(Networking)"] --> STG(Strategy)
E --> BH2[Define algorithm skeleton,<br> defer steps to subclasses] --> TM(Template Method)
E --> BH3["Encapsulate requests as objects<br>(Undo/Redo)"] --> CMD(Command)
E --> BH4[Separate operations from<br>objects they operate on] --> V(Visitor)
E --> BH5["Encapsulate state-specific<br>behavior<br>(Game States)"] --> STE(State)
E --> BH6["Maintain a consistent state by<br>being notified of changes<br>(KVO, Combine, Delegates)"] --> O(Observer)
E --> BH7[Traverse collections without<br>exposing internals] --> I(Iterator)
E --> BH8[Reduce coupling between<br>communicating objects] --> MED(Mediator)
E --> BH9[Capture and restore an<br>object's internal state] --> MEM(Memento)
E --> BH10[Provide a way to access elements<br>of an aggregate object sequentially] --> CHN(Chain of Responsibility)
E --> BH11[Convert the interface of a class<br>into another interface clients expect] --> INT(Interpreter);
end
subgraph Memory_Management_Patterns["Memory Management Patterns"]
direction LR
M --> MM1[Automatic Reference Counting] --> ARC(ARC)
M --> MM2[Manual Reference Counting] --> MRC(MRC)
M --> MM3[Retain Cycles] --> RC(Retain Cycles)
M --> MM4[Object Pooling] --> OP(Object Pool)
end
style CR1 fill:#1f1111,stroke:#fed7aa
style CR2 fill:#1f1111,stroke:#fed7aa
style CR3 fill:#1f1111,stroke:#fed7aa
style CR4 fill:#1f1111,stroke:#fed7aa
style CR5 fill:#1f1111,stroke:#fed7aa
style CR6 fill:#1f1111,stroke:#fed7aa
style ST1 fill:#1f1111,stroke:#fed7aa
style ST2 fill:#1f1111,stroke:#fed7aa
style ST3 fill:#1f1111,stroke:#fed7aa
style ST4 fill:#1f1111,stroke:#fed7aa
style ST5 fill:#1f1111,stroke:#fed7aa
style ST6 fill:#1f1111,stroke:#fed7aa
style ST7 fill:#1f1111,stroke:#fed7aa
style ST8 fill:#1f1111,stroke:#fed7aa
style BH1 fill:#121f91,stroke:#82b366
style BH2 fill:#121f91,stroke:#82b366
style BH3 fill:#121f91,stroke:#82b366
style BH4 fill:#121f91,stroke:#82b366
style BH5 fill:#121f91,stroke:#82b366
style BH6 fill:#121f91,stroke:#82b366
style BH7 fill:#121f91,stroke:#82b366
style BH8 fill:#121f91,stroke:#82b366
style BH9 fill:#121f91,stroke:#82b366
style BH10 fill:#121f91,stroke:#82b366
style BH11 fill:#121f91,stroke:#82b366
style MM1 fill:#1f1111,stroke:#feda11
style MM2 fill:#1f1111,stroke:#feda11
style MM3 fill:#1f1111,stroke:#feda11
style MM4 fill:#1f1111,stroke:#feda11
style S fill:#e1d5,stroke:#1a73a6
style FM fill:#e1d5,stroke:#1a73a6
style AF fill:#e1d5,stroke:#1a73a6
style P fill:#e1d5,stroke:#1a73a6
style BLD fill:#e1d5,stroke:#1a73a6
style BO fill:#e1d5,stroke:#1a73a6
style F fill:#818129,stroke:#9673a6
style AD fill:#818129,stroke:#9673a6
style CP fill:#818129,stroke:#9673a6
style PR fill:#818129,stroke:#9673a6
style DC fill:#818129,stroke:#9673a6
style BR fill:#818129,stroke:#9673a6
style FW fill:#818129,stroke:#9673a6
style AGG fill:#818129,stroke:#9673a6
style STG fill:#d51114,stroke:#82b366
style TM fill:#d51114,stroke:#82b366
style CMD fill:#d51114,stroke:#82b366
style V fill:#d51114,stroke:#82b366
style STE fill:#d51114,stroke:#82b366
style O fill:#d51114,stroke:#82b366
style I fill:#d51114,stroke:#82b366
style MED fill:#d51114,stroke:#82b366
style MEM fill:#d51114,stroke:#82b366
style CHN fill:#d51114,stroke:#82b366
style INT fill:#d51114,stroke:#82b366
style ARC fill:#c511f3,stroke:#824c68
style MRC fill:#c511f3,stroke:#824c68
style RC fill:#c511f3,stroke:#824c68
style OP fill:#c511f3,stroke:#824c68
style C fill:#c111f3,stroke:#824c68
style D fill:#623ddd,stroke:#fbbd20
style E fill:#911297,stroke:#4d884d
style M fill:#f199,stroke:#4d884d
style B fill:#e91f11,stroke:#b85450
style A fill:#4e899f,stroke:#6c8ebf
S -.-> SI1(Single instance<br>'static let shared = ...')
FM -.-> SI2(Single instance<br>of concrete factory)
FM -.-> IM("Implement<br>using:<br>'protocol Product { ... }'<br>'protocol Factory { ... }'")
FM -.-> CFD(Configure factory<br>dynamically)
CFD -.-> SI3(Single instance<br>of factory manager)
AF -.-> IM2(Implement using:<br>Multiple factories<br>conforming to a protocol)
P -.-> IM3("Implement using:<br>'NSCopying' (ObjC)<br>Custom 'clone()' (Swift)")
BLD -.-> IM4(Implement using:<br>Separate 'Builder' class<br>with fluent interface)
BO -.-> IM4
BO -.-> USO(Use for:<br>Complex object creation<br>with many options)
F -.-> USF(Use for:<br>Networking, Database access)
AD -.-> IM5("Implement using:<br>Protocol extensions (Swift)<br>Category (ObjC)<br>Wrapper class")
AD -.-> USO2(Use for:<br>Bridging Swift/ObjC/C++)
CP -.-> CC(Creating composites<br>of 'UIView's)
CP -.-> IM6(Implement using:<br>Recursive data structure)
PR -.-> USPR(Use for:<br>Lazy loading, access control)
DC -.-> AR(Add responsibility<br>to objects dynamically)
DC -.-> OU(Often uses)
CP -.-> CU(Composed using)
CP -.-> CSSVG(Chaining skin versus guts<br>Good for 'UITableViewCell')
FW -.-> USFW(Use for:<br>Drawing large numbers<br>of similar objects)
AGG -.-> IMAG(Implement Using<br>Multiple Services and Combine)
AGG -.-> USAG(Use for<br>Microservices, Data Aggregation)
STG -.-> DAS(Define algorithm<br>steps as protocols)
STG -.-> IM7("Implement using:<br>'protocol Algorithm { ... }'")
STG -.-> USSTG(Use for:<br>Networking protocols,<br>Data processing)
TM -.-> IM8(Implement using:<br>'open' and 'final' methods)
TM -.-> USTM(Use for:<br>Customizable 'UIViewController's)
CMD -.-> IM9("Implement using:<br>'protocol Command { ... }'<br>Invoker, Receiver")
CMD -.-> USCMD(Use for:<br>Undo/Redo, Operations)
V -.-> IM10(Implement using:<br>Double dispatch)
V -.-> USV(Use for:<br>Operating on a hierarchy<br>of objects)
STE -.-> IM11("Implement using:<br>'enum State { ... }'<br>Context class")
STE -.-> USSTE(Use for:<br>Game states, UI states)
O -.-> IMO(Implement using:<br>Delegates, Notifications,<br>Combine, KVO)
O -.-> USO3(Use for:<br>Reacting to model changes)
I -.-> IMI("Implement using:<br>'IteratorProtocol' (Swift)")
I -.-> USI(Use for:<br>Custom collection types)
MED -.-> IMMED(Implement using:<br>Centralized communication object)
MED -.-> USMED(Use for:<br>Complex UI interactions)
MEM -.-> IMMEM(Implement using:<br>Originator, Caretaker, Memento)
MEM -.-> USMEM(Use for:<br>Saving and restoring game state)
CHN -.-> IMCHN(Implement using:<br>Chain of handlers)
CHN -.-> USCHN(Use for:<br>Event handling, Error handling)
INT -.-> IMINT("Implement using:<br>Abstract Syntax Tree<br>(AST)")
INT -.-> USINT(Use for:<br>Parsing, DSLs)
ARC -.-> IMARC(Swift's primary memory management)
MRC -.-> IMMRC(Objective-C, manual retain/release)
RC -.-> IMARC
RC -.-> IMRC
RC -.-> UMRC(Use Weak/Unowned References)
OP -.-> IMOP(Reusable objects to avoid allocation)
OP -.-> USOP(UITableViewCells, UICollectionReusableView)
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This software is licensed under the MIT License. You may use, copy, modify, merge, publish, distribute, and sublicense it, provided that you include the original license in all copies or substantial portions of the software.
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