对于 Iphone，如何从当前加载的视图中引用根视图控制器，以便可以替换/切换视图

Posted 2023-02-27

【中文标题】对于 Iphone，如何从当前加载的视图中引用根视图控制器，以便可以替换/切换视图

【英文标题】：For Iphone how to reference root view controller from currently loaded view, so view can be replaced/switched

【发布时间】：2009-10-29 17:51:25

【问题描述】：

我正在尝试用新的视图切换当前加载的视图。

我有 3 个 xib 文件和 3 组 ViewControllerFiles。

RootViewController 正确加载，并且正确加载 HomeViewController。

当前出错的行是这个

[self.rootViewController.view insertSubview:gameController.view atIndex:1];

**error: request for member 'view' in something not a structure or a union**

如果有人能指出我正确的方向，那就太好了。我了解如何从根控制器切换视图，但我想从子视图交换/添加视图。有道理吗？

这里是根控制器头和实现：

#import <UIKit/UIKit.h>

@class HomeViewController;
@class GameViewController;

@interface RootViewController : UIViewController 
    HomeViewController *homeViewController;
    GameViewController *gameViewController;


@property (retain, nonatomic) HomeViewController *homeViewController;
@property (retain, nonatomic) GameViewController *gameViewController;

- (IBAction)showHome:(id)sender;
- (IBAction)showGame:(id)sender;

@end

实现文件：

#import "RootViewController.h"
#import "HomeViewController.h"
#import "GameViewController.h"

@implementation RootViewController

@synthesize homeViewController;
@synthesize gameViewController;

- (void)viewDidLoad 
    homeViewController.rootViewController = self;

    HomeViewController *homeController = [[HomeViewController alloc]    initWithNibName:@"HomeView" bundle:nil];
    self.homeViewController = homeController;   
    [self.view insertSubview:homeController.view atIndex:0];    
    [homeController release];   

    [super viewDidLoad];


- (void)didReceiveMemoryWarning 
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];    

    if (self.homeViewController.view.superview == nil) 
        self.homeViewController = nil;
     else 
        self.gameViewController = nil;


- (void)viewDidUnload 
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;


- (void)dealloc 
    [homeViewController release];
    [gameViewController release];   
    [super dealloc];


@end

这是正确加载的主视图文件：

#import <UIKit/UIKit.h>

@class RootViewController;

@interface HomeViewController : UIViewController   
//GameViewController *gameViewController;
    RootViewController *rootViewController;


//@property (retain, nonatomic) GameViewController *gameViewController;
@property (nonatomic, assign) RootViewController *rootViewController;

- (IBAction)showGame:(id)sender;

@end

实现文件：

#import "HomeViewController.h"
#import "RootViewController.h"

@implementation HomeViewController;

@synthesize rootViewController;

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad    
[super viewDidLoad];

- (IBAction)showGame:(id)sender
    GameViewController *gameController = [[GameViewController alloc] initWithNibName:@"GameView" bundle:nil];
    self.rootViewController = gameController;
    [self.rootViewController.view insertSubview:gameController.view atIndex:1];
    [gameController release];   


- (void)didReceiveMemoryWarning 
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];    
    // Release any cached data, images, etc that aren't in use.


- (void)viewDidUnload 
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;


- (void)dealloc 
    [super dealloc];


@end

【问题讨论】：

在哪里 [self.rootViewController.view insertSubview:gameController.view atIndex:1];被叫了？

在 HomeViewController 的实现文件中 - (IBAction)showGame:(id)sender GameViewController *gameController = [[GameViewController alloc] initWithNibName:@"GameView" bundle:nil]; self.rootViewController = 游戏控制器； [self.rootViewController.view insertSubview:gameController.view atIndex:1]; [游戏控制器发布]；

【参考方案1】：

我对你的评论感到困惑。这是附加代码sn-p：

- (IBAction)showGame:(id)sender  
    GameViewController *gameController = [[GameViewController alloc] initWithNibName:@"GameView" bundle:nil]; 
    self.rootViewController = gameController; 
    [self.rootViewController.view insertSubview:gameController.view atIndex:1];         
    [gameController release]; 

因此，您将 HomeViewController 的 rootViewController 设置为等于 gameController。然后将 gameController 视图插入到 rootViewController 的视图中。但是，gameController 是 rootViewController。我认为你这里有一个逻辑错误。

【参考方案2】：

幸运的是，这是一个简单的修复 - 您忘记包含 GameViewController 头文件。因此它不知道 GameViewController 实例的 view 属性是什么。

【参考方案3】：

我认为这是你的问题：

- (void)viewDidLoad 

homeViewController.rootViewController = self;

HomeViewController *homeController = [[HomeViewController alloc]  initWithNibName:@"HomeView" bundle:nil];
self.homeViewController = homeController; 

在初始化homeViewController 之前，您将rootViewController 分配给homeViewController。那时'self.homeViewController'只是空内存。