ALButton 是 UIButton 的子类，添加了一些功能，减少 UIButton 自定义外观和行为的行数，并且添加了一些 Swfit 的优势。
三种初始化方式：
//- 1. Full Initialization let style = ALButton.ButtonStyle() //-- set style let myButton = ALButton(title: "Button Title", style: style, touchUpInsideHandler: { (sender ) in //-- Implement touch up inside event here }) //- 2. Simple initialization with style: var style = ALButton.ButtonStyle() //-- set style let myButton = ALButton(title: "Button Title", style: style) //- 3. Short initialization let myButton = ALButton(title: "Button Title")
