IOS页面跳转的方法

在页面跳转时，若想用pushViewController，则必须在AppDelegate设置UINavigationController，否则pushViewController无效。
并且用pushViewController从A跳往B后，在B页面自带“Back”按钮返回上一页。类似于

这样设置，在AppDelegate中

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
    UIViewController *controllerA = [[ViewController alloc]init];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:controllerA];
    
    self.window.rootViewController = nav;
    [self.window makeKeyAndVisible];
    
    return YES;
}

在controllerA中的跳转页面方法中这样写

-(void)turnToOtherController{
    ControllerB *controllerB = [[ControllerB alloc]init];
    [self.navigationController pushViewController:controllerB animated:YES];
}

这样，导航条就会一直存在。若不想要导航条，那么在AppDelegate这样写

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
    UIViewController *controllerA = [[ViewController alloc]init];
    self.window.rootViewController = controllerA;
    [self.window makeKeyAndVisible];
    
    return YES;
}

而下面这种方法是通用的，无需设置rootViewController。

[self presentViewController:mainView animated:YES completion:nil];//controller自带的属性

下面的则需要

[self.navigationController pushViewController:mainView animated:YES];
//必须在AppDelegate设置UINavigationController，否则pushViewController无效。
//并且使用pushViewController后，在B页面，会自带一个“Back”按钮返回上一页。