内存管理和特性
// RetainTrackCategory.m// MemoryManager//// Created by 110 on 10-1-26.// Copyright 2010 __MyCompanyName__. All rights reserved.//#import "RetainTrackCategory.h"/** 类别:是一种为现有的类添加新方法的方式。 只有保证类别名称的唯一性,你可以向一个类添加任意多的类别 */@implementation RetainTrackCategory (RetainTrackCategory) -(NSString *) print{NSLog(@"pring-------");}@end?