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justFI's solution

to Hello World in the Objective-C Track

Published at May 13 2021 · 1 comment
Instructions
Test suite
Solution

The classical introductory exercise. Just say "Hello, World!".

"Hello, World!" is the traditional first program for beginning programming in a new language or environment.

The objectives are simple:

  • Write a function that returns the string "Hello, World!".
  • Run the test suite and make sure that it succeeds.
  • Submit your solution and check it at the website.

If everything goes well, you will be ready to fetch your first real exercise.

Setup

There are two different methods of getting set up to run the tests with Objective-C:

  • Create an Xcode project with a test target which will run the tests.
  • Use the ruby gem objc as a test runner utility.

Both are described in more detail here: http://exercism.io/languages/objective-c

Submitting Exercises

When submitting an exercise, make sure your solution file is in the same directory as the test code.

The submit command will look something like:

exercism submit <path-to-exercism-workspace>/objective-c/hello-world/HelloWorld.m

You can find the Exercism workspace by running exercism debug and looking for the line beginning with Workspace.

Source

This is an exercise to introduce users to using Exercism http://en.wikipedia.org/wiki/%22Hello,_world!%22_program

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

HelloWorldTest.m

#import <XCTest/XCTest.h>

#if __has_include("HelloWorldExample.h")
# import "HelloWorldExample.h"
# else
# import "HelloWorld.h"
#endif

NS_ASSUME_NONNULL_BEGIN

@interface HelloWorldTest : XCTestCase

@end

@implementation HelloWorldTest

- (HelloWorld *)helloWorld {
  return [[HelloWorld alloc] init];
}

- (void)testNoName {
  NSString *input = nil;
  NSString *expected = @"Hello, World!";
  NSString *result = [[self helloWorld] hello:input];
  XCTAssertEqualObjects(expected, result);
}

- (void)testSampleName {
  NSString *input = @"Alice";
  NSString *expected = @"Hello, Alice!";
  NSString *result = [[self helloWorld] hello:input];
  XCTAssertEqualObjects(expected, result);
}
  
- (void)testOtherSampleName {
  NSString *input = @"Bob";
  NSString *expected = @"Hello, Bob!";
  NSString *result = [[self helloWorld] hello:input];
  XCTAssertEqualObjects(expected, result);
}

@end
NS_ASSUME_NONNULL_END
//
//  HelloWorld.m
//  ExerciseName-Tests.
//
//  Created by yanghui on 2021/5/13.
//

#import "HelloWorld.h"

@implementation HelloWorld

- (NSString *)hello:(NSString *)string {
    return [NSString stringWithFormat:@"Hello, %@!", string?:@"World"];

}
@end

Community comments

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Avatar of justFI
justFI
Solution Author
commented 40 days ago

good

What can you learn from this solution?

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

  • What compromises have been made?
  • Are there new concepts here that you could read more about to improve your understanding?