1,695
students have developed their Objective-C skills on Exercism.

Students
1,695
Submissions
1,788
Mentoring Discussions
74

The Objective-C track needs attention ⚠️

Building

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Use your knowledge to build the Objective-C track itself

Build Test Runners

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Create Test Runners that have the single responsibility of taking a solution, running all tests and returning a standardized output.

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Build Analyzers

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Build an Analyzer for Objective-C: Exercism's analyzers automatically assess student's submissions and provide mentor-style commentary.

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Build Representers

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Build a Representer: a bit of code that has the single responsibility of taking a solution and returning a normalized representation of it.

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Create Practice Exercises

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Practice Exercises are exercises designed to allow students to solve an arbitrary problem, with the aim of them making use of the concepts they have learned so far.

Next goal: Implement 129 practice exercises. Find out more.

Usage statistics

51 active practice exercises
Started
Attempts
Completions
Mentoring requests
Hello World Hello World
480
351 (avg. 0.7)
246 (51.2%)
0 (0.0%)
Bob Bob
228
283 (avg. 1.2)
185 (81.1%)
21 (9.2%)
Difference of Squares Difference of Squares
55
64 (avg. 1.2)
42 (76.4%)
5 (9.1%)
Gigasecond Gigasecond
52
58 (avg. 1.1)
42 (80.8%)
3 (5.8%)
Leap Leap
76
85 (avg. 1.1)
63 (82.9%)
5 (6.6%)
Reverse String Reverse String
38
37 (avg. 1.0)
26 (68.4%)
1 (2.6%)
Space Age Space Age
37
34 (avg. 0.9)
30 (81.1%)
1 (2.7%)
Sum of Multiples Sum of Multiples
42
48 (avg. 1.1)
32 (76.2%)
1 (2.4%)
Two Fer Two Fer
105
101 (avg. 1.0)
57 (54.3%)
27 (25.7%)
ETL ETL
32
32 (avg. 1.0)
25 (78.1%)
0 (0.0%)
Flatten Array Flatten Array
21
25 (avg. 1.2)
15 (71.4%)
0 (0.0%)
Grade School Grade School
41
43 (avg. 1.0)
31 (75.6%)
0 (0.0%)
Hamming Hamming
91
108 (avg. 1.2)
84 (92.3%)
4 (4.4%)
Isogram Isogram
18
24 (avg. 1.3)
14 (77.8%)
0 (0.0%)
Nucleotide Count Nucleotide Count
41
49 (avg. 1.2)
37 (90.2%)
3 (7.3%)
Prime Factors Prime Factors
15
12 (avg. 0.8)
9 (60.0%)
0 (0.0%)
Raindrops Raindrops
38
37 (avg. 1.0)
26 (68.4%)
3 (7.9%)
RNA Transcription RNA Transcription
10
12 (avg. 1.2)
7 (70.0%)
0 (0.0%)
Atbash Cipher Atbash Cipher
11
12 (avg. 1.1)
8 (72.7%)
0 (0.0%)
Clock Clock
13
12 (avg. 0.9)
8 (61.5%)
0 (0.0%)
Collatz Conjecture Collatz Conjecture
8
8 (avg. 1.0)
5 (62.5%)
0 (0.0%)
Grains Grains
8
8 (avg. 1.0)
6 (75.0%)
0 (0.0%)
Perfect Numbers Perfect Numbers
11
9 (avg. 0.8)
8 (72.7%)
0 (0.0%)
Phone Number Phone Number
26
28 (avg. 1.1)
24 (92.3%)
1 (3.8%)
Robot Name Robot Name
27
28 (avg. 1.0)
21 (77.8%)
0 (0.0%)
Scrabble Score Scrabble Score
13
11 (avg. 0.8)
8 (61.5%)
0 (0.0%)
Secret Handshake Secret Handshake
8
7 (avg. 0.9)
5 (62.5%)
0 (0.0%)
Series Series
8
3 (avg. 0.4)
3 (37.5%)
0 (0.0%)
Sieve Sieve
8
6 (avg. 0.8)
5 (62.5%)
0 (0.0%)
Strain Strain
8
6 (avg. 0.8)
5 (62.5%)
0 (0.0%)
Sublist Sublist
15
14 (avg. 0.9)
10 (66.7%)
0 (0.0%)
Triangle Triangle
13
8 (avg. 0.6)
7 (53.8%)
0 (0.0%)
Acronym Acronym
10
9 (avg. 0.9)
7 (70.0%)
0 (0.0%)
All Your Base All Your Base
13
8 (avg. 0.6)
8 (61.5%)
0 (0.0%)
Allergies Allergies
10
11 (avg. 1.1)
7 (70.0%)
0 (0.0%)
Anagram Anagram
39
49 (avg. 1.3)
36 (92.3%)
1 (2.6%)
Beer Song Beer Song
12
11 (avg. 0.9)
9 (75.0%)
0 (0.0%)
Binary Search Binary Search
8
8 (avg. 1.0)
4 (50.0%)
0 (0.0%)
Crypto Square Crypto Square
7
3 (avg. 0.4)
3 (42.9%)
0 (0.0%)
Largest Series Product Largest Series Product
8
6 (avg. 0.8)
5 (62.5%)
0 (0.0%)
Meetup Meetup
9
7 (avg. 0.8)
4 (44.4%)
0 (0.0%)
Nth Prime Nth Prime
8
7 (avg. 0.9)
4 (50.0%)
0 (0.0%)
Pangram Pangram
10
5 (avg. 0.5)
5 (50.0%)
0 (0.0%)
Pascal's Triangle Pascal's Triangle
7
7 (avg. 1.0)
4 (57.1%)
0 (0.0%)
Say Say
5
2 (avg. 0.4)
2 (40.0%)
0 (0.0%)
Transpose Transpose
6
3 (avg. 0.5)
3 (50.0%)
0 (0.0%)
Word Count Word Count
51
65 (avg. 1.3)
48 (94.1%)
2 (3.9%)
Matching Brackets Matching Brackets
8
7 (avg. 0.9)
4 (50.0%)
0 (0.0%)
Luhn Luhn
10
8 (avg. 0.8)
5 (50.0%)
0 (0.0%)
Roman Numerals Roman Numerals
6
4 (avg. 0.7)
4 (66.7%)
0 (0.0%)
Run-Length Encoding Run-Length Encoding
10
5 (avg. 0.5)
5 (50.0%)
0 (0.0%)
78 unimplemented practice exercises
Affine Cipher Affine Cipher
Alphametics Alphametics
Armstrong Numbers Armstrong Numbers
Bank Account Bank Account
Binary Search Tree Binary Search Tree
Book Store Book Store
Bottle Song Bottle Song
Bowling Bowling
Change Change
Circular Buffer Circular Buffer
Complex Numbers Complex Numbers
Connect Connect
Custom Set Custom Set
D&D Character D&D Character
DOT DSL DOT DSL
Darts Darts
Diamond Diamond
Dominoes Dominoes
Error Handling Error Handling
Food Chain Food Chain
Forth Forth
Go Counting Go Counting
Grep Grep
Hangman Hangman
High Scores High Scores
House House
ISBN Verifier ISBN Verifier
Killer Sudoku Helper Killer Sudoku Helper
Kindergarten Garden Kindergarten Garden
Knapsack Knapsack
Ledger Ledger
Lens Person Lens Person
Linked List Linked List
List Ops List Ops
Markdown Markdown
Matrix Matrix
Micro Blog Micro Blog
Minesweeper Minesweeper
OCR Numbers OCR Numbers
POV POV
PaaS I/O PaaS I/O
Palindrome Products Palindrome Products
Parallel Letter Frequency Parallel Letter Frequency
Pig Latin Pig Latin
Poker Poker
Protein Translation Protein Translation
Proverb Proverb
Pythagorean Triplet Pythagorean Triplet
Queen Attack Queen Attack
REST API REST API
Rail Fence Cipher Rail Fence Cipher
Rational Numbers Rational Numbers
React React
Rectangles Rectangles
Resistor Color Resistor Color
Resistor Color Duo Resistor Color Duo
Resistor Color Trio Resistor Color Trio
Robot Simulator Robot Simulator
Rotational Cipher Rotational Cipher
SGF Parsing SGF Parsing
Saddle Points Saddle Points
Satellite Satellite
Scale Generator Scale Generator
Simple Cipher Simple Cipher
Simple Linked List Simple Linked List
Spiral Matrix Spiral Matrix
Square Root Square Root
State of Tic-Tac-Toe State of Tic-Tac-Toe
Tournament Tournament
Tree Building Tree Building
Twelve Days Twelve Days
Two Bucket Two Bucket
Variable Length Quantity Variable Length Quantity
Word Search Word Search
Wordy Wordy
Yacht Yacht
Zebra Puzzle Zebra Puzzle
Zipper Zipper