UIViewController

UIViewController是所有控制器的父类：

层次关系如下：

2.重要属性：

view

title

interfaceOrientation

3.重要方法

-(void)viewDidAppear:(BOOL)animated{}-(void)viewWillAppear:(BOOL)animated{}-(void)viewWillDisappear:(BOOL)animated{}-(void)viewDidDisappear:(BOOL)animated{}-(void)viewDidLoad{}- (instancetype)initWithCoder:(NSCoder *)coder{    self = [super initWithCoder:coder];    if (self) {            }    return self;}-(void)loadView{}