Learn OBJECTIVE-C with Real Code Examples

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int count = 0;
        BOOL isDark = NO;

        void (^updateUI)(void) = ^{
        NSLog(@"Counter: %d", count);
        NSLog(@"Theme: %@", isDark ? @"Dark" : @"Light");
        };

        void (^increment)(void) = ^{ count++; updateUI(); };
        void (^decrement)(void) = ^{ count--; updateUI(); };
        void (^reset)(void) = ^{ count = 0; updateUI(); };
        void (^toggleTheme)(void) = ^{ isDark = !isDark; updateUI(); };

        // Simulate actions
        updateUI();
        increment();
        increment();
        toggleTheme();
        decrement();
        reset();
    }
    return 0;
}

Demonstrates a simple counter with theme toggling using Objective-C console output (can be adapted for iOS apps).

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        for (int i = 1; i <= 3; i++) {
        int num = arc4random_uniform(100) + 1;
        NSLog(@"Random %d: %d", i, num);
        }
    }
    return 0;
}

Generates random numbers between 1 and 100 and prints them.

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSMutableArray *todos = [NSMutableArray array];

        void (^addTask)(NSString *) = ^(NSString *task){ [todos addObject:task]; NSLog(@"%@", todos); };
        void (^removeTask)(NSInteger) = ^(NSInteger index){ [todos removeObjectAtIndex:index]; NSLog(@"%@", todos); };

        // Simulate actions
        addTask(@"Buy milk");
        addTask(@"Write Objective-C code");
        removeTask(0);
    }
    return 0;
}

Maintains a simple todo list with add and remove functionality.

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        for (int i = 1; i <= 3; i++) {
        int roll = arc4random_uniform(6) + 1;
        NSLog(@"Roll %d: %d", i, roll);
        }
    }
    return 0;
}

Rolls a six-sided dice three times.

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int count = 5;
        while(count >= 0) {
        NSLog(@"Countdown: %d", count);
        count--;
        }
        NSLog(@"Done!");
    }
    return 0;
}

Counts down from 5 to 0.

#import <Foundation/Foundation.h>

BOOL isPrime(int n){
    if(n<2) return NO;
    for(int i=2;i*i<=n;i++){
        if(n%i==0) return NO;
    }
    return YES;
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int nums[] = {7,10,13};
        for(int i=0;i<3;i++){
        NSLog(@"%d is %@", nums[i], isPrime(nums[i])?@"Prime":@"Not Prime");
        }
    }
    return 0;
}

Checks if numbers are prime.

#import <Foundation/Foundation.h>

float cToF(float c){ return c*9/5 +32; }
float fToC(float f){ return (f-32)*5/9; }

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSLog(@"25°C = %.1f°F", cToF(25));
        NSLog(@"77°F = %.1f°C", fToC(77));
    }
    return 0;
}

Converts Celsius to Fahrenheit and vice versa.

#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;
}

Adds and removes items in a shopping cart with total cost.

#import <Foundation/Foundation.h>

void greet(NSString *name){
    NSLog(@"Hello, %@! Welcome!", name);
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        greet(@"Saurav");
        greet(@"Alice");
        greet(@"Bob");
    }
    return 0;
}

Greets users by name.

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int time = 0;
        while(time < 5){
        NSLog(@"Stopwatch: %d seconds", time);
        time++;
        }
        NSLog(@"Done!");
    }
    return 0;
}

Simulates a stopwatch incrementing seconds.