视图控制器UIViewController，视图控制，在新版本xcode中会默认生成一个ViewController。
（一）新建UIViewController
右键->New File添加一个继承自UIViewController的类View1Controller，在viewDidLoad中添加button，并设置button点击事件为关闭此ViewController
self.view.backgroundColor=[UIColor redColor]; UIButton *closeViewBtn=[[UIButton alloc] init]; closeViewBtn.backgroundColor=[UIColor blueColor]; closeViewBtn.frame=CGRectMake(10, 30, 100, 30); [closeViewBtn setTitle:@"Close" forState:UIControlStateNormal]; [closeViewBtn addTarget:self action:@selector(closeView) forControlEvents:UIControlEventTouchDown]; [self.view addSubview:closeViewBtn];
点击事件
-(void) closeView { [self dismissViewControllerAnimated:YES completion:^{}]; }
（二）在ViewController中添加一个button用来控制View1Controller的启动出现
//ViewController UIButton *showView1Btn=[[UIButton alloc] init]; showView1Btn.frame=CGRectMake(10, 470, 100, 30); showView1Btn.backgroundColor=[UIColor redColor]; [showView1Btn addTarget:self action:@selector(showView1:) forControlEvents:UIControlEventTouchDown]; [self.view addSubview:showView1Btn];
-(void) showView1:(UIButton *)showView1Btn { View1Controller *view1=[[View1Controller alloc] init]; [self presentViewController:view1 animated:YES completion:^{}]; }
通过上述两步可以实现视图的简单切换。
（三）视图的生命周期
在view1Controller中添加如下代码，在其启动过程中可以看到除viewDidLoad外其他方法的触发以及启动顺序
-(void) loadView { [super loadView]; NSLog(@"Load view"); } -(void) viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; NSLog(@"View will appear"); } -(void) viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; NSLog(@"View did appear"); } -(void) viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; NSLog(@"View will disappear"); } -(void) viewDidDisappear:(BOOL)animated { [super viewDidDisappear:animated]; NSLog(@"View did disappear"); } -(void) closeView { [self dismissViewControllerAnimated:YES completion:^{}]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. }
原文：https://www.cnblogs.com/llstart-new0201/p/9690508.html