iOS开发 －UIScrollView详解

http://blog.csdn.net/wangzi11322/article/details/45913049

UIScrollView

移动设备的屏幕大小是极其有限的，因此直接展示在用户眼前的内容也相当有限 
当展示的内容较多，超出一个屏幕时，用户可通过滚动手势来查看屏幕以外的内容 
普通的UIView不具备滚动功能，不能显示过多的内容 
UIScrollView是一个能够滚动的视图控件，可以用来展示大量的内容，并且可以通过滚动查看所有的内容

举例：手机上的“设置”、其他示例程序

UIScrollView的用法

将需要展示的内容添加到UIScrollView中 
设置UIScrollView的contentSize属性，告诉UIScrollView所有内容的尺寸，也就是告诉它滚动的范围（能滚多远，滚到哪里是尽头）

UIScrollView无法滚动的解决办法

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">如果<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>无法滚动，可能是以下原因：<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1.</span>没有设置contentSize<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2.</span>scrollEnabled = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NO</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.</span>没有接收到触摸事件:userInteractionEnabled = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NO</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4.</span>没有取消autolayout功能（要想scrollView滚动，必须取消autolayout）</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

UIScrollView的代理（delegate）

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">很多时候，我们想在<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>正在滚动 或 滚动到某个位置 或者 停止滚动 时做一些特定的操作要想完成上述功能，前提条件就是能够监听到<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的整个滚动过程当<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>发生一系列的滚动操作时， 会自动通知它的代理（delegate）对象，给它的代理发送相应的消息，让代理得知它的滚动情况也就是说，要想监听<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的滚动过程，就必须先给<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>将delegate需要实现的方法都定义在了<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollViewDelegate</span>协议中，因此要想成为<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的delegate，必须遵守<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollViewDelegate</span>协议，然后实现协议中相应的方法，就可以监听<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的滚动过程了</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

UIScrollView和控制器

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">一般情况下，就设置<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>所在的控制器 为 <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的delegate设置控制器为<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的delegate有<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>种方法：通过代码（<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">self</span>就是控制器）<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">self</span><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.scrollView</span><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">.delegate</span> = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">self</span>;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

通过storyboard拖线（右击UIScrollView）

UIScrollView的常见属性

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">CGPoint</span> contentOffset; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//这个属性用来表示UIScrollView滚动的位置</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">CGSize</span> contentSize; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//这个属性用来表示UIScrollView内容的尺寸，滚动范围（能滚多远）</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIEdgeInsets</span> contentInset; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//这个属性能够在UIScrollView的4周增加额外的滚动区域</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> bounces;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置UIScrollView是否需要弹簧效果</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>,getter=isScrollEnabled) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> scrollEnabled; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置UIScrollView是否能滚动</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> showsHorizontalScrollIndicator;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//是否显示水平滚动条</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> showsVerticalScrollIndicator;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//是否显示垂直滚动条</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

UIScrollView的常用代理方法

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 用户开始拖拽时调用</span>- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewWillBeginDragging:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 滚动到某个位置时调用</span>- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewDidScroll:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 用户结束拖拽时调用</span>- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewDidEndDragging:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView willDecelerate:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span>)decelerate;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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>

UIScrollView的缩放

当用户在UIScrollView身上使用捏合手势时，UIScrollView会给代理发送一条消息，询问代理究竟要缩放自己内部的哪一个子控件（哪一块内容） 
1.实现UIScrollViewDelegate协议

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 用户使用捏合手势时调用</span>- (<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIView</span> *)viewForZoomingInScrollView:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

遵守协议，实现相应的方法

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span><<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollViewDelegate</span>> delegate</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

当用户在UIScrollView身上使用捏合手势时，UIScrollView会调用代理的viewForZoomingInScrollView:方法，这个方法返回的控件就是需要进行缩放的控件

缩放实现步骤

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">设置<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span><UISCrollViewDelegate> delegate代理对象设置minimumZoomScale ：缩小的最小比例设置maximumZoomScale ：放大的最大比例让代理对象实现下面的方法，返回需要缩放的视图控件- (<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIView</span> *)viewForZoomingInScrollView:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView;跟缩放相关的其他代理方法缩放完毕的时候调用 - (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewWillBeginZooming:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView withView:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIView</span> *)view正在缩放的时候调用- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewDidZoom:(<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span> *)scrollView</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

UIScrollView和UIPageControl的分页

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">只要将<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>的pageEnabled属性设置为<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span>，<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIScrollView</span>会被分割成多个独立页面，里面的内容就能进行分页展示一般会配合UIPageControl增强分页效果，UIPageControl常用属性如下 <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//一共有多少页</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSInteger</span> numberOfPages;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//当前显示的页码</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSInteger</span> currentPage; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//只有一页时，是否需要隐藏页码指示器</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> hidesForSinglePage; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//其他页码指示器的颜色</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>,retain) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIColor</span> *pageIndicatorTintColor;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//当前页码指示器的颜色</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">@property</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nonatomic</span>,retain) <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIColor</span> *currentPageIndicatorTintColor;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

NSTimer的使用

NSTimer叫做“定时器”，它的作用如下 
在指定的时间执行指定的任务 
每隔一段时间执行指定的任务

<code class="hljs css has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">调用下面的方法就会开启一个定时任务+ (<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">NSTimer</span> *)<span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">scheduledTimerWithTimeInterval</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(NSTimeInterval)ti</span>                              <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">target</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(id)aTarget</span>                                 <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">selector</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(SEL)aSelector</span>                                 <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">userInfo</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(id)userInfo</span>                                 <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">repeats</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:(BOOL)yesOrNo</span>;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><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></ul>

每隔ti秒，调用一次aTarget的aSelector方法，yesOrNo决定了是否重复执行这个任务

通过invalidate方法可以停止定时器的工作，一旦定时器被停止了，就不能再次执行任务。只能再创建一个新的定时器才能执行新的任务

<code class="hljs erlang has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-pp" style="box-sizing: border-box;">- <span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(void)</span>invalidate;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; 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; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

UIScrollView实例

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** *      1.成为代理的条件：    UIScrollView将delegate需要实现的方法都定义在了UIScrollViewDelegate协议中，    因此要想成为UIScrollView的delegate，必须遵守UIScrollViewDelegate协议，    然后实现协议中相应的方法，就可以监听UIScrollView的滚动过程了    2.设置UIScrollView的id<UISCrollViewDelegate> delegate代理对象    设置minimumZoomScale ：缩小的最小比例    设置maximumZoomScale ：放大的最大比例    让代理对象实现下面的方法，返回需要缩放的视图控件    - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView; */</span>#<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ViewController.h"</span><span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@interface</span> ViewController () <UIScrollViewDelegate><span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@property</span> (weak, nonatomic) IBOutlet UIScrollView *scrollView;<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@property</span> (weak, nonatomic) IBOutlet UIImageView *minionView;<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@end</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//委托 代理模式</span><span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@implementation</span> ViewController- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)viewDidLoad {    [<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span> viewDidLoad];    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置内容尺寸</span>    self.scrollView.contentSize=self.minionView.frame.size;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置</span>    self.scrollView.delegate=self;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置最大和最小的缩放比例</span>    self.scrollView.maximumZoomScale=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2.0</span>;    self.scrollView.minimumZoomScale=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.2</span>;}<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** *  当用户开始拖拽scrollView时就会调用 */</span>- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewWillBeginDragging:(UIScrollView *)scrollView{    NSLog(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"开始拖拽...."</span>);}<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** *  只要scrollView正在滚动,就会调用 */</span>- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)scrollViewDidScroll:(UIScrollView *)scrollView{    NSLog(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"正在滚动------%@"</span>,NSStringFromCGPoint(scrollView.contentOffset));}<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/** *  当用户使用捏合手势时就会调用 * <span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span> 返回的控件就是需要进行缩放的控件 */</span>- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView{    NSLog(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"开始缩放-----"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> self.minionView;}- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>) scrollViewDidZoom:(UIScrollView *)scrollView{    NSLog(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"正在缩放----"</span>);}</code>