monsoir/创建 navigation bar button 步骤.m

## 创建 navigation bar button 步骤.m
//创建并初始化一个 UIBarButtonItem 实例
UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithCustomView: btn];

//再将 item 与 导航栏 关联起来
self.navigationItem.leftBarButton = item;
	//创建并初始化一个 UIBarButtonItem 实例
	UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithCustomView: btn];

	//再将 item 与导航栏关联起来
	self.navigationItem.leftBarButton = item;