Video iOS 05-Three encapsulation of the big features

The main learning object-oriented three major features: encapsulation , inheritance and polymorphism in the encapsulation

1. Encapsulation1> Benefits

Reduced coupling ratio

Properties in a class that can be called repeatedly

Improve security , external can not arbitrarily modify the value of variables, to ensure the security of the data

2> Set method

1. Function: Provide a method to set the member variables of the outside world, can be in the method to face the parameters of the corresponding filter

2. Naming conventions

1> method name must begin with set

2> set followed by the name of the member variable , the first letter of the member variable must be capitalized

3> return value must be void

4> must receive a parameter, and the parameter type is consistent with the member variable type

The name of the 5> parameter cannot be the same as the member variable name

3> Get Method

1. Function: returns the member variable inside the object

2. Naming conventions

1> must have a return value , and the return type must be consistent with the member variable type

2> the method name is the member variable name minus The underscore _ , the member variable is defined, usually begins with an underscore _

3> does not need to receive any parameters

4> member Variables

Naming conventions: Be sure to start with the underscore _

Role:
1. Make the member variable and get method separate
2. Can be distinguished from Local variables , a variable that sees the beginning of an underscore, is usually a member variable

5> Object methods and class methods1. Object Methods

1> minus - start

2> can only be called by an object

access to member variables (instance variables) in the 3> object method

2. Class Methods

1> plus + start

2> can only be called by Class (name)

Member variables (instance variables) cannot be accessed in the 3> class method

3. Benefits of class methods

1> is not dependent on the object, the execution efficiency is high

2> can use class method as far as possible

3> occasions: You can change to a class method when you do not need to use a member variable inside a method

Allow class methods and object methods to have the same name

Sample code

1#import <Foundation/Foundation.h>2 3 //Define a gender enumeration4typedefenum {5 Sexman,6 Sexwoman7 } Sex;8 9 @interface Student:nsobjectTen { One     //member Variables A     int_no; - Sex _sex; - } the //Statement of the set and get methods of the sex -- (void) Setsex: (Sex) sex; --(Sex) sex; - @end +  - @implementation Student + //implementation of the set and get methods for sex A- (void) Setsex: (Sex) Sex { at_sex =sex; - } --(Sex) Sex { -     return_sex; - } - @end in  - intMain () { to     //Create a Student object +Student *stu = [StudentNew]; -     //call the Set method of the Stu object's gender the [Stu Setsex:sexman]; *     //get method to call Stu object gender $NSLog (@"%d", [stu Sex]); Panax Notoginseng      -     return 0; the}

Video iOS 05-Three encapsulation of the big features