前言

项目中有功能需要在代码中动态创建UGUI对象，但是在网上搜索了很久都没有找到类似的教程，最后终于在官方文档中找到了方法，趁着记忆犹新，写下动态创建UGUI的方法，供需要的朋友参考

你将学到什么？ 一、新建一个Test项目

首先我们新建一个名为Test的项目来实践我们这次的内容，项目创建成功后，我们新建一个Button对象，如下图：

新建Button对象

新的UGUI全部都基于一个Canvas画布，如果你的场景里面没有Canvas，当你创建一个UI对象时，编辑器会自动帮你创建一个Canvas

编辑器自动创建的Canvas

然后我们设置一下Cavans的缩放模式和尺寸，本例中我们以iPhone6的尺寸大小为准，我们选中Canvas，然后在其Canvas Scaler组件中，修改Ui Scale Mode为Scale With Screen Size，然后将
分辨率设置为750*1334

设置Cavans的缩放模式和尺寸

二、设置Button属性

然后我们将Button的位置调整至屏幕的右上方，然后将字体大小放大，文本内容修改为点我（这边大小和文本内容可以根据自己的喜好来调整）

将Button调整到右上方

三、动态创建UGUI对象的原理说明

在开始下面的内容之前，先在这边讲解一下动态创建UGUI对象的原理，我们看看Unity官方文档的介绍说明：（懒得看到大段文字的朋友可以直接跳过这段，看后面的简单说明）

Creating UI elements from scripting
If you are creating a dynamic UI where UI elements appear, disappear, or change based on user actions or other actions in the game, you may need to make a script that instantiates new UI elements based on custom logic.
Creating a prefab of the UI element
In order to be able to easily instantiate UI elements dynamically, the first step is to create a prefab for the type of UI element that you want to be able to instantiate. Set up the UI element the way you want it to look in the Scene, and then drag the element into the Project View to make it into a prefab.
For example, a prefab for a button could be a Game Object with a Image component and a Button component, and a child Game Object with a Text component. Your setup might be different depending on your needs.
You might wonder why we don’t have a API methods to create the various types of controls, including visuals and everything. The reason is that there are an infinite number of way e.g. a button could be setup. Does it use an image, text, or both? Maybe even multiple images? What is the text font, color, font size, and alignment? What sprite or sprites should the image use? By letting you make a prefab and instantiate that, you can set it up exactly the way you want. And if you later want to change the look and feel of your UI you can just change the prefab and then it will be reflected in your UI, including the dynamically created UI.
Instantiating the UI element
Prefabs of UI elements are instantiated as normal using the Instantiate method. When setting the parent of the instantiated UI element, it’s recommended to do it using the Transform.SetParent method with the worldPositionStays parameter set to false.
Positioning the UI element
A UI Element is normally positioned using its Rect Transform. If the UI Element is a child of a Layout Group it will be automatically positioned and the positioning step can be skipped.
When positioning a Rect Transform it’s useful to first determine it has or should have any stretching behavior or not. Stretching behavior happens when the anchorMin and anchorMax properties are not identical.
For a non-stretching Rect Transform, the position is set most easily by setting the anchoredPosition and the sizeDelta properties. The anchoredPosition specifies the position of the pivot relative to the anchors. The sizeDelta is just the same as the size when there’s no stretching.
For a stretching Rect Transform, it can be simpler to set the position using the offsetMin and offsetMax properties. The offsetMin property specifies the corner of the lower left corner of the rect relative to the lower left anchor. The offsetMax property specifies the corner of the upper right corner of the rect relative to the upper right anchor.
Customizing the UI Element
If you are instantiating multiple UI elements dynamically, it’s unlikely that you’ll want them all to look the same and do the same. Whether it’s buttons in a menu, items in an inventory, or something else, you’ll likely want the individual items to have different text or images and to do different things when interacted with.
This is done by getting the various components and changing their properties. See the scripting reference for the Image and Text components, and for how to work with UnityEvents from scripting.

动态创建UGUI对象的方法，简单来说就是将我们需要创建的UGUI对象制作成一个Prefab，然后使用Instantiate方法将其实例化，最后使用相关的API对其属性进行动态设置

四、制作自定义的Text Prefab

接下来我们就来创建自定义的Text Prefab，为动态创建做准备，首先我们会自定义一个如下图所示的Text：