Objective-C

Module 1 – Objective-C — first steps

Page 1 of 3 · About 15 minutes per lesson, including practice.

Your first explainable program

15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.

A program is a set of instructions. Read the example from its entry point to the output statement. Text in quotes is data; the output operation is an instruction. Predict the printed line before running. Change only the message, run again, then remove one required punctuation mark and read the first error. Restore the working source.

Square brackets send a message to a receiver: [plan completed]. @interface declares methods and @implementation defines them. These GNUstep exercises use explicit memory management, not Apple ARC.

#import <Foundation/Foundation.h>
#include <stdio.h>
#include <assert.h>

int main(void) {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSString *message = @"Ready";
    puts([message UTF8String]);
    [pool drain];
    return 0;
}

Expected result: Ready

Practice and evidence

Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.

Language reference

Example code on Agila Forge ↗