###Document

  1. CABasicAnimation Keypath
  2. Animation Types and Timing Programming Guide
  3. CGAffineTransform
  4. Quartz 2D Programming Guide
  5. 放射变换
  6. 组合动画
  7. http://www.cnblogs.com/v2m_/archive/2013/05/09/3070187.html
  8. 几个常用动画代码