摘要：
loadView; This is where subclasses should create their custom view hierarchy if they aren't using a nib. Should never be called directly.这是当他们没有正在使用ni 阅读全文
摘要：
在介绍两种类方法之前，NSObject Class Reference里对这两个方法说明： ＋（void）initialize The runtime sends initialize to each class in a program exactly one time just before t 阅读全文