How to Create an Objective-c Singleton in 2025?

Creating a singleton in Objective-C has been a common pattern for sharing a single instance of a class across an entire application. As of 2025, the process remains straightforward but involves some key best practices to ensure thread safety and maintainability. Here’s a step-by-step guide to implementing a singleton in Objective-C:

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Step-by-Step Guide to Creating a Singleton

Step 1: Declare the Interface

In your class header file (e.g., MySingletonClass.h), declare a class method that will provide access to the singleton instance.

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@interface MySingletonClass : NSObject

+ (instancetype)sharedInstance;

@end

Step 2: Implement the Singleton

In the implementation file (e.g., MySingletonClass.m), define the sharedInstance method. The most efficient way to ensure thread safety and lazy instantiation is to use Grand Central Dispatch (GCD).

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#import "MySingletonClass.h"

@implementation MySingletonClass

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

@end

Step 3: Customize Initialization

Customize the init method if you need to perform additional setup when the singleton is first created. Ensure that the custom initializer is only called once.

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- (instancetype)init {
    self = [super init];
    if (self) {
        // Perform initialization of instance variables, if needed
    }
    return self;
}

Best Practices

• Thread Safety: Using dispatch_once ensures that your singleton is safely created even when accessed from multiple threads.
• Memory Management: The singleton instance should be allocated and initialized only once and live for the lifetime of the application.

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By following these guidelines, you can create a robust and efficient singleton in Objective-C while staying informed about trends and best practices across different programming languages. Use these insights to influence and enhance your development workflow.