Objective-C Tutorial i OBJECTIVE-C TUTORIAL Simply Easy Learning by tutorialspoint.com tutorialspoint.com TUTORIALS POINT Simply Easy Learning Page 1 ABOUT THE TUTORIAL Objective-c tutorial Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. This is the main programming language used by Apple for the OS X and iOS operating systems and their respective APIs, Cocoa and Cocoa Touch. This reference will take you through simple and practical approach while learning Objective-C Programming language. Audience This reference has been prepared for the beginners to help them understand the basic to advanced concepts related to Objective-C Programming languages. Prerequisites Before you start doing practice with various types of examples given in this reference, I'm making an assumption that you are already aware about what is a computer program and what is a computer programming language? Compile/Execute Objective-C Programs For most of the examples given in this tutorial, you will find Try it option to compile and execute Objective-C programs online, so just make use of it and enjoy your learning. Try the following example using Try it option available at the top right corner of the below sample code box: #import <Foundation/Foundation.h> int main() { /* my first program in Objective-C */ NSLog(@"Hello, World! \n"); return 0; } TUTORIALS POINT Simply Easy Learning Page 2 Table of Content Objective-c tutorial 1 Audience 1 Prerequisites 1 Compile/Execute Objective-C Programs 1 Objective-C Overview 9 Object-Oriented Programming 9 Example Code 9 Foundation Framework 9 Learning Objective-C 9 Use of Objective-C 10 Objective-C Environment Setup 11 Try it Option Online 11 Local Environment Setup 11 Text Editor 11 The GCC Compiler 11 Installation on UNIX/Linux 12 Installation on Mac OS 13 Installation on Windows 13 Objective-C Program Structure 14 Objective-C Hello World Example 14 Compile & Execute Objective-C Program: 15 Objective-C Basic Syntax 16 Tokens in Objective-C 16 Semicolons ; 16 Comments 16 Identifiers 17 Keywords 17 Whitespace in Objective-C 18 TUTORIALS POINT Simply Easy Learning Page 3 Objective-C Data Types 19 Integer Types 19 Floating-Point Types 20 The void Type 21 Objective-C Variables 22 Variable Definition in Objective-C: 22 Variable Declaration in Objective-C: 23 Example 24 Lvalues and Rvalues in Objective-C: 25 Objective-C Constants 26 Integer literals 26 Floating-point literals 26 Character constants 27 String literals 28 Defining Constants 28 The #define Preprocessor 28 Objective-C Operators 30 Arithmetic Operators 30 Relational Operators 30 Logical Operators 31 Bitwise Operators 31 Assignment Operators 32 Misc Operators ↦ sizeof & ternary 33 Operators Precedence in Objective-C 33 Arithmetic Operators in Objective-C 35 Example 35 Relational Operators in Objective-C 37 Example 37 Logical Operators in Objective-C 39 Example 39 Bitwise Operators in Objective-C 41 Example 41 Assignment Operators in Objective-C 43 Example 44 Size of and ternary operators in Objective-C 46 Example 46 Objective-C Loops 48 Loop Control Statements: 49 The Infinite Loop: 49 TUTORIALS POINT Simply Easy Learning Page 4 while loop in Objective-C 50 Syntax: 50 Flow Diagram: 50 Example: 51 For loop in Objective-C 52 Syntax: 52 Flow Diagram: 52 Example: 53 do while loop in Objective-C 54 Syntax: 54 Example: 55 nested loops in Objective-C 56 Syntax: 56 Example: 57 break statement in Objective-C 58 Syntax: 58 Flow Diagram: 58 Example: 59 continue statement in Objective-C 60 Syntax: 60 Flow Diagram: 60 Example: 61 Objective-C Decision Making 62 The ? : Operator: 63 Objective-C - if statement 64 Syntax: 64 Flow Diagram: 64 Example: 65 Objective-C - if else statement 66 Syntax: 66 Flow Diagram: 66 Example: 67 The if else if else Statement 67 Syntax: 67 Example: 68 Objective-C - nested if statements 69 Syntax: 69 Example: 69 Objective-C - switch statement 71 TUTORIALS POINT Simply Easy Learning Page 5 Syntax: 71 Flow Diagram: 72 Example: 72 Objective-C - nested switch statements 74 Syntax: 74 Example: 75 Objective-C Functions 76 Defining a Method 76 Example: 77 Method Declarations: 77 Calling a method: 77 Function Arguments: 78 Function call by value in Objective-C 80 Function call by reference in Objective-C 82 Objective-C Blocks 84 Simple Block declaration syntax 84 Here is a simple example 84 We can invoke the block using 84 Blocks Take Arguments and Return Values 84 Blocks using type definitions 85 Objective-C Numbers 86 Objective-C Arrays 88 Declaring Arrays 88 Initializing Arrays 88 Accessing Array Elements 89 Objective-C Arrays in Detail 90 Multi-dimensional arrays in Objective-C 91 Two-Dimensional Arrays: 91 Initializing Two-Dimensional Arrays: 91 Accessing Two-Dimensional Array Elements: 92 Passing Arrays as Function Arguments in Objective-C 93 Way-1 93 Way-2 93 Way-3 93 Example 93 Return array from function in Objective-C 96 Pointer to an Array in Objective-C 99 Objective-C Pointers 101 What Are Pointers? 101 TUTORIALS POINT Simply Easy Learning Page 6 How to use Pointers? 102 NULL Pointers in Objective-C 102 Objective-C Pointers in Detail: 103 Objective-C - Pointer arithmetic 104 Incrementing a Pointer 104 Decrementing a Pointer 105 Pointer Comparisons 105 Objective-C - Array of pointers 107 Objective-C - Pointer to Pointer 109 Passing pointers to functions in Objective-C 111 Return pointer from functions in Objective-C 113 Objective-C Strings 115 Objective-C Structures 118 Defining a Structure 118 Accessing Structure Members 119 Structures as Function Arguments 120 Pointers to Structures 121 Bit Fields 123 Objective-C Preprocessors 124 Preprocessors Examples 124 Predefined Macros 125 Preprocessor Operators 126 Macro Continuation (\) 126 Stringize (#) 126 Token Pasting (##) 126 The defined() Operator 127 Parameterized Macros 127 Objective-C Typedef 129 typedef vs #define 130 Objective-C Type Casting 131 Integer Promotion 131 Usual Arithmetic Conversion 132 Objective-C Log Handling 134 NSLog method 134 Disabling logs in Live apps 134 Objective-C Error Handling 135 NSError 135 Command-Line Arguments 138 Objective-C Classes & Objects 140 TUTORIALS POINT Simply Easy Learning Page 7 Objective-C characteristics 140 Objective-C Class Definitions: 140 Allocating and initializing Objective-C Objects: 141 Accessing the Data Members: 141 Properties: 142 Objective-C Inheritance 143 Base & Derived Classes: 143 Access Control and Inheritance: 145 Objective-C Polymorphism 146 Objective-C Data Encapsulation 149 Data Encapsulation Example: 149 Designing Strategy: 150 Objective-C Categories 151 Characteristics of category 151 Objective-C Posing 153 Restrictions in Posing 153 Objective-C Extensions 155 Characteristics of extensions 155 Extensions Example 155 Objective-C Protocols 157 Objective-C Dynamic Binding 160 Objective-C Composite Objects 162 Class Clusters 162 So what's exactly composite object? 162 A Composite Object example 163 Obj-C Foundation Framework 165 Foundation Classes based on functionality 165 Data Storage in Objective-C 166 NSArray & NSMutableArray 166 NSDictionary & NSMutableDictionary 167 NSSet & NSMutableSet 168 Text and strings in Objective C 170 NSCharacterSet 170 Dates and times in Objective-C 172 Exception handling in Objective-C 173 File Handling in Objective-C 174 Methods used in File Handling 174 Check if file exists at a path 174 Comparing two file contents 174 TUTORIALS POINT Simply Easy Learning Page 8 Check if writable, readable and executable 174 Move file 174 Copy file 175 Remove file 175 Read file 175 Write file 175 URL loading system in Objective-C 176 Objective-C Fast Enumeration 179 Collections in Objective-C 179 Fast enumeration Syntax 179 Fast Enumeration Backwards 180 Obj-C Memory Management 181 "Manual Retain-Release" or MRR 181 MRR Basic Rules 182 "Automatic Reference Counting" or ARC 183 [...]... 10:48:39.772 tutorials Point[1200] hello world TUTORIALS POINT Simply Easy Learning Page 13 3 CHAPTER Objective- C Program Structure Before we study basic building blocks of the Objective- C programming language, let us look a bare minimum Objective- C program structure so that we can take it as a reference in upcoming chapters Objective- C Hello World Example A Objective- C program basically consists of... list of some of such escape sequence codes: Escape sequence Meaning \\ \ character \' ' character \" " character \? ? character \a Alert or bell \b Backspace \f Form feed \n Newline \r Carriage return \t Horizontal tab \v Vertical tab \ooo Octal number of one to three digits \xhh Hexadecimal number of one or more digits Following is the example to show few escape sequence characters: #import ... the value 0 Compile & Execute Objective- C Program: Now when we compile and run the program, we will get the following result 2013-09-07 22:38:27.932 demo[28001] Hello, World! TUTORIALS POINT Simply Easy Learning Page 15 4 CHAPTER Objective- C Basic Syntax Y ou have seen a basic structure of Objective- C program, so it will be easy to understand other basic building blocks of the Objective- C programming... Learning Page 11 This GCC compiler will be used to compile your source code into final executable program I assume you have basic knowledge about a programming language compiler GCC compiler is available for free on various platforms and the procedure to set up on various platforms is explained below Installation on UNIX/Linux The initial step is install gcc along with gcc Objective- C package This is done... Learning Page 18 5 CHAPTER Objective- C Data Types I n the Objective- C programming language, data types refer to an extensive system used for declaring variables or functions of different types The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted The types in Objective- C can be classified as follows: S.N Types and Description 1 Basic Types: They... variable The name of a variable can be composed of letters, digits, and the underscore character It must begin with either a letter or an underscore Upper and lowercase letters are distinct because Objective- C is casesensitive Based on the basic types explained in previous chapter, there will be the following basic variable types: Type Description char Typically a single octet (one byte) This is an integer... declaration where you provide a function name at the time of its declaration and its actual definition can be given anywhere else In the following example, it's explained using C function and as you know Objective- C supports C style functions also: // function declaration int func(); int main() { // function call int i = func(); } // function definition int func() { return 0; } TUTORIALS POINT Simply Easy... Character constants Character literals are enclosed in single quotes e.g., 'x' and can be stored in a simple variable of char type A character literal can be a plain character (e.g., 'x'), an escape sequence (e.g., '\t'), or a universal character (e.g., '\u0 2C0 ') There are certain characters in C when they are proceeded by a backslash they will have special meaning and they are used to represent like... have one text editor in place and you have enough experience to write a computer program, save it in a file, compile it and finally execute it The GCC Compiler The source code written in source file is the human readable source for your program It needs to be "compiled" to turn into machine language, so that your CPU can actually execute the program as per instructions given TUTORIALS POINT Simply Easy... Whitespace in Objective- C A line containing only whitespace, possibly with a comment, is known as a blank line, and an Objective- C compiler totally ignores it Whitespace is the term used in Objective- C to describe blanks, tabs, newline characters and comments Whitespace separates one part of a statement from another and enables the compiler to identify where one element in a statement, such as int, ends and . Objective- C Program Structure 14 Objective- C Hello World Example 14 Compile & Execute Objective- C Program: 15 Objective- C Basic Syntax 16 Tokens in Objective- C 16 Semicolons ; 16 Comments. 78 Function call by value in Objective- C 80 Function call by reference in Objective- C 82 Objective- C Blocks 84 Simple Block declaration syntax 84 Here is a simple example 84 We can invoke. Return pointer from functions in Objective- C 113 Objective- C Strings 115 Objective- C Structures 118 Defining a Structure 118 Accessing Structure Members 119 Structures as Function Arguments 120