OBJECTIVE-C Classes and objects

Simple use of 0.NSString

1. Class encapsulation, data protection;

2.setter and Getter methods;

3.self,supper,id

4. Initialization method;

5. Class methods

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0, NSString Simple use

NSString is the OC string class;

@“....” A string object;

NSString *s = @ "I am a string";

1. Permissions for instance variables in classes

Requirements: Access member variables;

1) Encapsulation of classes, protection of data

2) Three permissions and default permissions

@public, @protected, @private

Default in OC is @protected

"Variable Permissions"

Dog:name,age,weight

Special methods:

"Set method and get Method"

Set method Function: Modify/set member variables;

Get method function: Gets the member variable value;

Named:

Set method:-(void) Setxxxx: (parameter type) parameter name;

Get method:-(return value type) getxxxx;

"Test1"

Practice:

Human: Name NSString *,age, school number;

1.set method Setting member variables

The 2.get method gets the value of each member variable

"Self,supper,id"

1) ID type, is the pointer type;

ID: Generic object pointer, similar to C-language void *

ID type can point to any object type, do not need to force the reload, can be used directly;

"ID Sample"

Practice:

"Composite class Design"

Refrigerator icebox storage items (ID)

Refrigerator class: Icebox

Elephant class: Elephant

Human: Person

Dogs: Dog

The refrigerator opens the door;

The refrigerator stores the item ID and prints out the item type;

Refrigerator closed;

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Requirements: How do I invoke other methods inside a method?

Self and supper in the instance method?

1) Super

Super: The keyword used to invoke the parent class method;//temporarily understand the following

2) Self

Self: A pointer to the current object, with a pointer to the current object in each object, which is self;

Methods within the class can be called to each other using self

5.3. Initialization method

"How to initialize the method" -(ID) init;

Initialize the member variable when the object is created by the function of the Initialize method;

Initialize method format

1, without parameters of the construction method

-(ID) init;

2, the construction method with the parameter

-(ID) initwithxxxx: (parameter type) parameter 1 [Label]:(parameter type) parameter 2 ...;

Practice:

1. Create a road, member variables have length and width, write a construction method for length and width, and setter getter methods.

Construction method: Requires no parameters and two versions with parameters, without parameters, the default length is 1000, width is 1;

"Road"

2. There is a car class, price prices, brand type;

Three initialization methods;

Create and initialize a car by price

Create and initialize your car through branding

Create and initialize cars with price and branding

"Car"

Class 3.5 Methods

"Dog"

class method function:

"Create an object from a class method"

Member methods (instance methods)

Class method:

Practice:

1. Create a Postcard class card

Property:

Name

Unit

Phone number

Method:

Construction method (with parameters and without parameters)

creating objects from class methods (with parameters and without parameters)

Display information methods:

Homework:

1. Create a bank account class

Property:

Account number

Password

Storage Amount

Storage life

Method:

Construction method

Setup, account number, password

Deposit

Set years

Withdrawal

2. There is a fraction of the class, containing the numerator and denominator, to implement the construction, set the value method, to achieve two points of the +,

-, *,/arithmetic;

OBJECTIVE-C Classes and objects