iOS SDK詳解之UIScreen

轉載自：http://blog.csdn.net/hello_hwc/article/details/46955529

原創Blog，轉載請註明出處
blog.csdn.net/hello_hwc
歡迎關注我的iOS SDK詳解專欄
http://blog.csdn.net/column/details/huangwenchen-ios-sdk.html
不知不覺這個專欄已經寫了45篇文章了，我想應該至少還有100篇吧。iOS開發的東西太多太多

---

前言：UIScreen封裝訪問着硬件顯示屏相關的信息。一個iOS設備通暢只有一個硬件顯示屏。當然，如果通過USB或者無線投影到其他顯示器的時候，就有可能有多個。

對於鏈接多個屏幕的情況，本文並不會講解，因爲絕大多數App用不到這個功能。

---

獲取主屏幕對象

<code class="hljs fix has-numbering"><span class="hljs-attribute">UIScreen * screen </span>=<span class="hljs-string"> [UIScreen mainScreen];</span></code><ul class="pre-numbering" style=""><li>1</li></ul><ul class="pre-numbering" style=""><li>1</li></ul>

---

截屏

利用的當前在Screen上的部分生成一個UIView，利用這個UIVIew可以做一些全屏的動畫。注意，這樣的效果是比生成一副圖片的效率要高的。

<code class="hljs erlang has-numbering"><span class="hljs-pp">- <span class="hljs-params">(<span class="hljs-variable">UIView</span> * nonnull)</span>snapshotViewAfterScreenUpdates:<span class="hljs-params">(<span class="hljs-variable">BOOL</span>)</span>afterUpdates
</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

例如

<code class="hljs avrasm has-numbering">    self<span class="hljs-preprocessor">.view</span><span class="hljs-preprocessor">.backgroundColor</span> = [UIColor redColor]<span class="hljs-comment">;</span>
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(<span class="hljs-number">2</span> * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        UIScreen * mainScreen  = [UIScreen mainScreen]<span class="hljs-comment">;</span>
        UIView * snapshot = [mainScreen snapshotViewAfterScreenUpdates:NO]<span class="hljs-comment">;</span>
        snapshot<span class="hljs-preprocessor">.frame</span> = CGRectMake(<span class="hljs-number">0</span>, <span class="hljs-number">0</span>,mainScreen<span class="hljs-preprocessor">.bounds</span><span class="hljs-preprocessor">.size</span><span class="hljs-preprocessor">.width</span>/<span class="hljs-number">2</span>,mainScreen<span class="hljs-preprocessor">.bounds</span><span class="hljs-preprocessor">.size</span><span class="hljs-preprocessor">.height</span>/<span class="hljs-number">2</span>)<span class="hljs-comment">;</span>
        snapshot<span class="hljs-preprocessor">.center</span> = self<span class="hljs-preprocessor">.view</span><span class="hljs-preprocessor">.center</span><span class="hljs-comment">;</span>
        [self<span class="hljs-preprocessor">.view</span> addSubview:snapshot]<span class="hljs-comment">;</span>
        self<span class="hljs-preprocessor">.view</span><span class="hljs-preprocessor">.backgroundColor</span> = [UIColor whiteColor]<span class="hljs-comment">;</span>

    })<span class="hljs-comment">;</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li></ul>

效果

---

座標系相關

• coordinateSpace

這個函數返回遵循UICoordinateSpace協議的對象，這個協議封裝了座標系的信息以及座標系轉換的函數。UIView和UIScreen的對象都實現了這個協議。

<code class="hljs objectivec has-numbering">    UIScreen * screen = [UIScreen mainScreen];
    <span class="hljs-keyword">id</span><UICoordinateSpace> coor = [screen coordinateSpace];
    [<span class="hljs-keyword">self</span> LogFrame:[coor bounds]];</code><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li></ul>

把UIView的一個點進行座標系轉換到固定的UIScreen座標系

<code class="hljs avrasm has-numbering">[myView convertPoint:point toCoordinateSpace:myView<span class="hljs-preprocessor">.window</span><span class="hljs-preprocessor">.screen</span><span class="hljs-preprocessor">.fixedCoordinateSpace</span>]<span class="hljs-comment">;</span></code><ul class="pre-numbering" style=""><li>1</li></ul><ul class="pre-numbering" style=""><li>1</li></ul>

• fixedCoordinateSpace

和上文CoordinateSpace唯一不同的是，這個返回的是 portrait-up的座標系，也就是說是不變的。而CoordinateSpace會隨着設備下旋轉而改變。

---

Bounds/NativeBounds

• bounds 以點爲單位，隨着屏幕方向變化而變化
• NativeBounds 以像素爲單位，固定爲portrait-up的座標系

舉例
監聽屏幕旋轉並且log

<code class="hljs objectivec has-numbering">-(<span class="hljs-keyword">void</span>)didRotateFromInterfaceOrientation:(<span class="hljs-built_in">UIInterfaceOrientation</span>)fromInterfaceOrientation{
    UIScreen * screen = [UIScreen mainScreen];
    [<span class="hljs-keyword">self</span> LogFrame:[screen bounds]];
    [<span class="hljs-keyword">self</span> LogFrame:[screen nativeBounds]];
}</code><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li></ul>

豎

<code class="hljs css has-numbering">2015<span class="hljs-tag">-07-19</span> 18<span class="hljs-pseudo">:02</span><span class="hljs-pseudo">:27</span><span class="hljs-class">.417</span> <span class="hljs-tag">NewOcTest</span><span class="hljs-attr_selector">[2615:147772]</span> 0<span class="hljs-class">.000000</span> 0<span class="hljs-class">.000000</span> 320<span class="hljs-class">.000000</span> 480<span class="hljs-class">.000000</span>
2015<span class="hljs-tag">-07-19</span> 18<span class="hljs-pseudo">:02</span><span class="hljs-pseudo">:27</span><span class="hljs-class">.417</span> <span class="hljs-tag">NewOcTest</span><span class="hljs-attr_selector">[2615:147772]</span> 0<span class="hljs-class">.000000</span> 0<span class="hljs-class">.000000</span> 640<span class="hljs-class">.000000</span> 960<span class="hljs-class">.000000</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

橫

<code class="hljs css has-numbering">2015<span class="hljs-tag">-07-19</span> 18<span class="hljs-pseudo">:02</span><span class="hljs-pseudo">:23</span><span class="hljs-class">.455</span> <span class="hljs-tag">NewOcTest</span><span class="hljs-attr_selector">[2615:147772]</span> 0<span class="hljs-class">.000000</span> 0<span class="hljs-class">.000000</span> 480<span class="hljs-class">.000000</span> 320<span class="hljs-class">.000000</span>
2015<span class="hljs-tag">-07-19</span> 18<span class="hljs-pseudo">:02</span><span class="hljs-pseudo">:23</span><span class="hljs-class">.456</span> <span class="hljs-tag">NewOcTest</span><span class="hljs-attr_selector">[2615:147772]</span> 0<span class="hljs-class">.000000</span> 0<span class="hljs-class">.000000</span> 640<span class="hljs-class">.000000</span> 960<span class="hljs-class">.000000</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

---

NativeScale/Scale

從一個point到像素點的轉換關係。例如：在普通屏幕上，1個點對應一個像素，5s和6等視網膜顯示屏1個點對應4個像素。在6p上，一個點對應9個像素。

普通屏幕上

<code class="hljs cs has-numbering">NativeScale<span class="hljs-comment">//1</span>
Scale <span class="hljs-comment">//1</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

5s 6

<code class="hljs cs has-numbering">NativeScale<span class="hljs-comment">//2</span>
Scale <span class="hljs-comment">//2</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

6p

<code class="hljs cs has-numbering">NativeScale<span class="hljs-comment">//3</span>
Scale <span class="hljs-comment">//3</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

---

亮度

通過修改屬性brightness來修改亮度。

---

Screen Mode

三個屬性

• preferredMode 偏好的顯示模式
• availableModes 支持的顯示模式
• currentMode 當前的顯示模式

返回對象是UIScreenMode，包含了

• size 屏幕的大小，以像素爲單位
• pixelAspectRatio,像素的橫縱比

舉例

<code class="hljs avrasm has-numbering">    UIScreen * screen = [UIScreen mainScreen]<span class="hljs-comment">;</span>
    UIScreenMode  *perferedMode = screen<span class="hljs-preprocessor">.preferredMode</span><span class="hljs-comment">;</span>
    NSLog(@<span class="hljs-string">"Width:%f Height:%f AspectRatio:%f"</span>,perferedMode<span class="hljs-preprocessor">.size</span><span class="hljs-preprocessor">.width</span>,perferedMode<span class="hljs-preprocessor">.size</span><span class="hljs-preprocessor">.height</span>,perferedMode<span class="hljs-preprocessor">.pixelAspectRatio</span>)<span class="hljs-comment">;</span></code><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li><li>3</li></ul>

5s輸出

<code class="hljs css has-numbering">2015<span class="hljs-tag">-07-19</span> 20<span class="hljs-pseudo">:42</span><span class="hljs-pseudo">:00</span><span class="hljs-class">.791</span> <span class="hljs-tag">NewOcTest</span><span class="hljs-attr_selector">[860:31850]</span> <span class="hljs-tag">Width</span><span class="hljs-pseudo">:640</span><span class="hljs-class">.000000</span> <span class="hljs-tag">Height</span><span class="hljs-pseudo">:1136</span><span class="hljs-class">.000000</span> <span class="hljs-tag">AspectRatio</span><span class="hljs-pseudo">:1</span><span class="hljs-class">.000000</span>
</code><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul><ul class="pre-numbering" style=""><li>1</li><li>2</li></ul>

---