What Are Some Common Objective-c Design Patterns in 2025?

Common Objective-C Design Patterns in 2025

As we progress further into 2025, Objective-C remains a relevant and critical language for iOS and macOS application development. Despite the rise of Swift, many legacy systems and applications still utilize Objective-C, making it essential for developers to grasp its design patterns to maintain and improve these systems effectively. Here’s a look at some of the most common Objective-C design patterns you’ll encounter today.

1. Model-View-Controller (MVC)

MVC is arguably the most widely used design pattern in Objective-C app development. It bifurcates the application structure into three interconnected components: - Model: Manages the data, logic, and rules of the application. - View: Displays the data to the user and sends user commands to the controller. - Controller: Acts as an intermediary between model and view, updating the view as the model changes.

Benefits:

• Separation of Concerns: Each component handles different aspects, making it easy to manage and scale applications.

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2. Singleton Pattern

The Singleton pattern restricts the instantiation of a class to one “single” instance. This is particularly useful when exactly one object is needed to coordinate actions throughout the system.

Implementation:

A Singleton in Objective-C is often implemented using a static variable and a class method to return the shared instance.

+ (instancetype)sharedManager {
    static MyManager *sharedManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedManager = [[self alloc] init];
    });
    return sharedManager;
}

3. Observer Pattern

The Observer pattern enables a subject to notify a list of observers about any state changes, typically implemented using the NSNotificationCenter in Objective-C.

Use Case:

Utilize this pattern when you need different parts of your application to react to specific events or changes in application state.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleNotification:) name:@"CustomNotificationName" object:nil];

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4. Delegation Pattern

The Delegation pattern allows an object to hand off tasks and responsibilities to another object. It is implemented using protocols in Objective-C, providing a clean way to respond to changes or actions occurring in other objects.

Example:

A common use is with UITableView, where the delegate provides information about which rows are visible and interacts with row selections.

@protocol MyDelegate <NSObject>
- (void)didPerformAction;
@end

@interface MyClass : NSObject
@property (nonatomic, weak) id<MyDelegate> delegate;
@end

5. Blocks

Objective-C blocks are a powerful feature that provides a way to create function pointers on the fly. They are often used for callbacks, completion handlers, or iterations.

Benefit:

Utilize blocks to encapsulate units of computation efficiently and pass them within your program.

For a detailed exploration on documenting these, visit Objective-C blocks.

Conclusion

Understanding and implementing these design patterns can significantly enhance your Objective-C applications’ architecture. They offer a blueprint to create robust, reusable, and maintainable code, essential for the demands of complex applications in 2025. Whether you’re delving into legacy systems or creating new ones, mastering these patterns should be a part of every Objective-C developer’s toolkit.