工作备忘-位移枚举

开发中，我们经常看到很多的位移枚举，一般来说，见到位移枚举，我们都是可以写多个的，用 | 来隔开，就能识别。其实按照习惯的惯例，我们通常看到枚举，看不懂，就写个0，其实这样不好，还是要理解一下枚举的内容，是不是我们想要的
那么我们来模拟一下，看位移枚举，究竟是个什么东西

自定义一个枚举

根据位移的常识，我们得出了偏移后的数值

<code class="hljs d 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-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">typedef</span> NS_OPTIONS(NSUInteger, ActionType) {

ActionTypeUp    = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> << <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 1</span>
ActionTypeDown  = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> << <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 2</span>
ActionTypeRight = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> << <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>, <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 4</span>
ActionTypeLeft  = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> << <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>, <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 8</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></ul>

我们在一个方法里边：

<code class="hljs fsharp 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-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)action:(ActionType)<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span></span>
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> =</span>= <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span>;
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ((<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> & <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ActionTypeUp</span>) =</span>= ActionTypeUp)
{
NSLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">@"上"</span>);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ((<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> & <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ActionTypeDown</span>) =</span>= ActionTypeDown)
{
NSLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">@"下"</span>);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ((<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> & <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ActionTypeLeft</span>) =</span>= ActionTypeLeft)
{
NSLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">@"左"</span>);
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> ((<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> & <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ActionTypeRight</span>) =</span>= ActionTypeRight)
{
NSLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">@"右"</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><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li></ul>

那么我们在viewDidLoad中 这么搞：

<code class="hljs fsharp 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-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)viewDidLoad {
[super viewDidLoad];

ActionType <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> =</span> ActionTypeUp | ActionTypeLeft | ActionTypeRight | ActionTypeDown; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 15</span>
[self action:<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span>];</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>

其实这个东西，只要懂点二进制的位移的偏移，就知道是什么内容了