Swift3.0 - Type Casting 类型转换@H_404_1@
http://blog.csdn.net/brycegao321/article/details/53311964@H_404_1@
https://developer.apple.com/library/prerelease/content/documentation/Swift/Conceptual/Swift_Programming_Language/TypeCasting.html#//apple_ref/doc/uid/TP40014097-CH22-ID338
基类:
- classMediaItem{
- varname:String
- init(name:String){
- self.name=name
- }
- }