Object-C 面向对象的基本特征_object-c面对对象基础-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_17007915/article/details/49026589

封装

定义
 隐藏内部实现，稳定外部接口
 1.属性封装了实例变量
 2.方法封装了具体实现的代码
 3.类封装了属性和方法
 作用
 1.属性封装了实例变量
 2.方法封装了具体实现的代码
 3.类封装了属性和方法

继承

 为什使用继承？
在开发过程中，我们会发现很多代码相同，特别是创建一些类的时候，发现类于类之间有很多相同属性及方法，这些方法和属性会写很多次，如果程序员这样干，就很蛋疼了。在面向对象中，有继承的概念。我可以使用继承方式将相同的属性和方法放到一个类中，然后其他类继承于此类，我们将这种方式叫做继承。
继承即是让一个类拥有另一个类的某些属性和方法的特性。被继承的类称为父类(基类),继承类称为子类。子类可以直接拥有父类中的所有非私有成员和方法          

什么时候使用继承？

在开发中发现一些具有相同的特性和方法时，我们就使用继承。
在OC中只有单继承的概念，并没有多继承。

多态

 多态是建立在继承的基础上面
 1.继承同一父类的子类，他们本身具有自己的特性
 2.继承同一父类的子类，在执行同样的命令的时候，具有不同的效果

新建一个Role类，再新建两个类Hero,Monster类来继承于Role类
Role.h文件

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#import <span class="hljs-title" style="box-sizing: border-box;"><Foundation/Foundation.h></span></span>

<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@interface</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Role</span> : <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">NSObject</span></span>

-(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)attack:(Role *)role ;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@end</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

Role.m文件

<code class="hljs ruby has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#import "Role.h"</span>

<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@implementation</span> <span class="hljs-constant" style="box-sizing: border-box;">Role</span>

-(void)<span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">attack:</span>(<span class="hljs-constant" style="box-sizing: border-box;">Role</span> *)role
{
    <span class="hljs-constant" style="box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"正在攻击"</span>);
    <span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>里氏替换原则
     <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ([role <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">isMemberOfClass:</span>[<span class="hljs-constant" style="box-sizing: border-box;">Monster</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span>]])</span>
    {
        <span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>强转一下类型
        <span class="hljs-constant" style="box-sizing: border-box;">Monster</span> *m = (<span class="hljs-constant" style="box-sizing: border-box;">Monster</span> *)role ;
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ([role <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">isMemberOfClass:</span>[<span class="hljs-constant" style="box-sizing: border-box;">Hero</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span>]])</span>
    {
        <span class="hljs-constant" style="box-sizing: border-box;">Hero</span> *h = (<span class="hljs-constant" style="box-sizing: border-box;">Hero</span> *) role ;
    }
}

<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@end</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li></ul>

Hero.m文件

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#import <span class="hljs-title" style="box-sizing: border-box;">"Hero.h"</span></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#import <span class="hljs-title" style="box-sizing: border-box;">"Monster.h"</span></span>
<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@implementation</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Hero</span></span>

-(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)attack:(Role *)role
{
    [<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span> attack:role];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"hero attack"</span>);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@end</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

Monster.m文件

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#import <span class="hljs-title" style="box-sizing: border-box;">"Monster.h"</span></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#import <span class="hljs-title" style="box-sizing: border-box;">"Hero.h"</span></span>
<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@implementation</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Monster</span></span>

-(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)attack:(Role *)role
{
    [<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span> attack:role];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"monster attack"</span>);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@end</span></code>