IOS图层Layer学习笔记（五）—— CATextLayer

简介

CATextLayer提供了简单的文本布局，第一行是靠近顶部的。支持普通文本和属性文本。

属性

string

id， No Animatable。要显示的文本，类型可以使NSString或者NSAttributedString，默认值为nil。

font

CFTypeRef， No Animatable。使用的字体，只有当string类型为NSString时才有效。默认Helvetica字体。CFTypeRef 只是一个占位符，font支持的类型有NSString、CTFontRef、CGFontRef，其中NSString 必须是支持的字体名称。

<code class="hljs cs 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;">// 设置textLayer的字体为Bradley Hand</span>
textLayer.font = (__bridge CFTypeRef _Nullable)(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">@"Bradley Hand"</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></ul><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></ul>

fontSize

CGFloat， Animatable。字体大小，只有当string类型为NSString时才有效。默认36.0。

foregroundColor

CGColorRef， Animatable。文本颜色，默认不透明白色。动画效果仅支持OS X 10.6以上版本，不支持iOS。

wrapped（isWrapped）

BOOL， No Animatable。自动换行。 

truncationMode

NSString *， No Animatable。当字符串显示不全的时候的裁剪方式。可选以下值：

<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-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCATruncationNone;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 不剪裁，默认</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCATruncationStart;   <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 剪裁开始部分</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCATruncationEnd;     <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 剪裁结束部分</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCATruncationMiddle;  <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 剪裁中间部分</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></ul><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></ul>

alignmentMode

NSString *， No Animatable。字符串对齐方式。

<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-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCAAlignmentNatural;   <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 自然对齐，默认</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCAAlignmentLeft;      <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 左对齐</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCAAlignmentRight;     <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 右对齐</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCAAlignmentCenter;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 居中</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> kCAAlignmentJustified; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 两端对齐</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></ul><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></ul>