Mode:
Duration:
1
Coding works best on desktop or with an external keyboard.
Shopping Cart - Objective-c Typing CST Test
Shopping Cart — Objective-c Code
Adds and removes items in a shopping cart with total cost.
#import <Foundation/Foundation.h>
int main(int argc, const char * argv[]) {
@autoreleasepool {
NSMutableArray *cart = [NSMutableArray array];
NSMutableArray *prices = [NSMutableArray array];
void (^addItem)(NSString*, NSNumber*) = ^(NSString *item, NSNumber *price){
[cart addObject:item];
[prices addObject:price];
NSLog(@"Cart: %@", cart);
NSLog(@"Total: %@", [prices valueForKeyPath:@"@sum.self"]);
};
void (^removeItem)(NSInteger) = ^(NSInteger index){
[cart removeObjectAtIndex:index];
[prices removeObjectAtIndex:index];
NSLog(@"Cart: %@", cart);
NSLog(@"Total: %@", [prices valueForKeyPath:@"@sum.self"]);
};
// Simulate actions
addItem(@"Apple", @2);
addItem(@"Banana", @3);
removeItem(0);
}
return 0;
}Objective-c Language Guide
Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to C. It has been the primary language for macOS and iOS development before Swift, enabling developers to create applications for Apple platforms with dynamic runtime capabilities.
Primary Use Cases
- ▸macOS and iOS application development
- ▸Legacy Apple framework integration
- ▸Developing Cocoa and Cocoa Touch applications
- ▸Creating reusable Objective-C libraries
- ▸High-performance system-level Apple apps
Notable Features
- ▸Object-oriented with classes and categories
- ▸Dynamic runtime with message passing
- ▸Automatic Reference Counting (ARC) for memory management
- ▸Protocol-based polymorphism
- ▸Interoperable with C and C++ code
Origin & Creator
Developed in the early 1980s by Brad Cox and Tom Love, combining C with Smalltalk-style object-oriented messaging.
Industrial Note
Objective-C remains critical for maintaining legacy macOS and iOS applications and for interfacing with older Apple frameworks that are not fully migrated to Swift.
Quick Explain
- ▸Objective-C extends C with object-oriented features and a dynamic runtime.
- ▸It uses a messaging syntax inspired by Smalltalk, allowing flexible method calls and dynamic behavior.
- ▸Widely used in legacy iOS/macOS applications, frameworks, and libraries, though Swift is increasingly preferred for new development.
Core Features
- ▸C language foundation with object-oriented extensions
- ▸Selectors and dynamic messaging system
- ▸Categories for extending existing classes
- ▸Protocols for interface definition
- ▸Blocks for closures and callback functions
Learning Path
- ▸Learn C fundamentals
- ▸Understand object-oriented concepts in Objective-C
- ▸Practice message sending and method calls
- ▸Explore Cocoa/Cocoa Touch frameworks
- ▸Build and test simple iOS/macOS apps
Practical Examples
- ▸Defining classes and methods
- ▸Implementing delegate patterns
- ▸Using categories to extend functionality
- ▸Creating simple iOS/macOS apps
- ▸Interfacing Objective-C with C/C++ code
Comparisons
- ▸More verbose and lower-level than Swift
- ▸Provides dynamic runtime not present in Swift
- ▸Better for legacy Apple projects
- ▸Full C interoperability, unlike Swift in early versions
- ▸Declining popularity as Swift adoption grows
Strengths
- ▸Stable and mature language with long Apple ecosystem support
- ▸Full access to low-level C performance and system APIs
- ▸Dynamic runtime enables flexible behaviors
- ▸Large codebase of libraries and frameworks
- ▸Still supported in Xcode for iOS/macOS development
Limitations
- ▸Verbosity and less readable syntax compared to modern Swift
- ▸Steeper learning curve for newcomers
- ▸Manual memory management pre-ARC can be error-prone
- ▸Slower adoption of modern language features
- ▸Declining community focus compared to Swift
When NOT to Use
- ▸New iOS/macOS projects (prefer Swift)
- ▸Cross-platform development outside Apple ecosystem
- ▸Projects requiring modern, concise syntax
- ▸Applications prioritizing rapid prototyping
- ▸Non-Apple platform development
Cheat Sheet
- ▸@interface / @implementation - class declaration
- ▸@property - declare class properties
- ▸@protocol - define interfaces
- ▸[object method] - send message
- ▸ARC - automatic memory management
FAQ
- ▸Is Objective-C free?
- ▸Yes, open-source compiler and Apple frameworks.
- ▸Can Objective-C run on Windows?
- ▸Not natively; primarily macOS/iOS platforms.
- ▸Is Objective-C still relevant?
- ▸Yes, for legacy apps and Apple framework interoperability.
- ▸Can Objective-C work with Swift?
- ▸Yes, mixed projects support interoperability.
- ▸Is Objective-C object-oriented?
- ▸Yes, it extends C with object-oriented features and messaging.
30-Day Skill Plan
- ▸Week 1: C basics and Objective-C syntax
- ▸Week 2: Classes, methods, and memory management
- ▸Week 3: Delegates, protocols, and categories
- ▸Week 4: Framework integration (UIKit, AppKit)
- ▸Week 5: Building and debugging full apps
Final Summary
- ▸Objective-C is a mature, dynamic, object-oriented language for Apple platforms.
- ▸It provides full C interoperability and access to Cocoa/Cocoa Touch frameworks.
- ▸Still essential for maintaining legacy iOS/macOS applications.
- ▸ARC and runtime features simplify memory management and dynamic behaviors.
- ▸Swift is now the preferred language for new development, but Objective-C knowledge remains valuable.
Project Structure
- ▸Classes/ - Objective-C class files
- ▸Resources/ - images, XIBs, storyboards
- ▸Frameworks/ - linked Apple or third-party libraries
- ▸Tests/ - unit and UI tests
- ▸Supporting Files/ - plist and configuration files
Monetization
- ▸App Store distribution
- ▸Enterprise iOS/macOS applications
- ▸Custom frameworks for commercial software
- ▸Legacy system maintenance contracts
- ▸Training and consulting for Objective-C apps
Productivity Tips
- ▸Use Xcode templates and snippets
- ▸Leverage Interface Builder for UI design
- ▸Regularly refactor to maintain readability
- ▸Automate builds and tests with Xcode schemes
- ▸Use CocoaPods or Swift Package Manager for dependencies
Basic Concepts
- ▸Classes, objects, and methods
- ▸Instance and class variables
- ▸Message passing using selectors
- ▸Protocols and delegates
- ▸Memory management (ARC and manual retain/release)
Official Docs
- ▸Apple Developer Objective-C documentation
- ▸Cocoa and Cocoa Touch framework references
- ▸Clang/LLVM Objective-C compiler docs