iphone - 将子视图添加到窗口后无法推送模态视图？答案

【问题标题】：iphone - cant push modal views after adding subview to window?iphone - 将子视图添加到窗口后无法推送模态视图？
【发布时间】：2011-05-12 17:32:00
【问题描述】：

在我的应用程序中，我有以下代码，当我的应用程序启动时，第一位运行，并在模式视图中显示登录屏幕。在此之前将我的 rootController 添加到窗口中。

模态视图将允许用户登录、查看条款和条件，然后如果他们接受，则调用 loadMainApp 函数。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    rootController.delegate = self;
    [window addSubview:rootController.view];

    LoginViewController *_loginViewController = [[LoginViewController alloc] initWithNibName:@"LoginView" bundle:[NSBundle mainBundle]];
    self.loginViewController = _loginViewController;
    [_loginViewController release];


    UINavigationController *navi = [[[UINavigationController alloc]initWithRootViewController:loginViewController]autorelease];

    navi.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
    [loginViewController release];
    [rootController presentModalViewController:navi animated:YES];

    [self.window makeKeyAndVisible];
    return YES;
}

当用户接受条款和条件时调用下一位：

-(void)loadMainApp:(UIView *)fromView{

    [fromView removeFromSuperview];
    [window addSubview:rootController.view];
    rootController.selectedIndex = 2;
    rootController.delegate = self;

}

从这里我希望能够使用作为模态视图的人员选择器，我尝试使用以下代码：

 ABPeoplePickerNavigationController *picker =
        [[ABPeoplePickerNavigationController alloc]init];
        picker.peoplePickerDelegate = self;

        [rootController presentModalViewController:picker animated:YES];
        [picker release];

但是什么也没有发生，当我尝试从我的 rootController 呈现一个模态视图时，什么也没有显示。

这似乎发生在 applicationDidFinishLaunching 中的这段代码运行后：

LoginViewController *_loginViewController = [[LoginViewController alloc] initWithNibName:@"LoginView" bundle:[NSBundle mainBundle]];
        self.loginViewController = _loginViewController;
        [_loginViewController release];


        UINavigationController *navi = [[[UINavigationController alloc]initWithRootViewController:loginViewController]autorelease];

        navi.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
        [loginViewController release];
        [rootController presentModalViewController:navi animated:YES];

        [self.window makeKeyAndVisible];
        return YES;

如果我根本不显示登录屏幕，而是添加我的 rootController

rootController.delegate = self;
        [window addSubview:rootController.view];

在 applicationDidFinishLaunching 函数中，当我显示人员选择器时一切正常。

我在这里打破了一些基本的东西，或者任何人都可以发现我可能做错了什么？

【问题讨论】：

标签： iphone ios uinavigationcontroller presentmodalviewcontroller abpeoplepickerview

【解决方案1】：

您是否通过dismissModalViewControllerAnimated: 方法正确关闭了第一个模态视图控制器？如果您只是从其父视图中删除模态视图控制器的视图，那么 UIKit 可能会取消很多文书工作。

【讨论】：

【解决方案2】：

你真正应该做的是这样的：

将 rootViewController 添加到 navigationController。然后将 navigationController 添加到窗口中。
在 rootViewController 的 viewDidLoad 方法中，将 loginViewController 的委托设置为 rootViewController，并将 LoginViewController 的实例显示为模态。
完成条款接受后，执行 [delegate loginViewControllerFinished];。
现在在 rootViewController 中，处理 loginViewControllerFinished 方法。这应该包含对 [self dismissModalViewControllerAnimated:YES] 的调用；关闭登录模式视图。然后您应该启动 ABPeoplePickerNavigationController作为模式视图。

在 AppDelegate 中：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Make sure rootViewController is initiated by this point.

    UINavigationController *navigationController = [[[UINavigationController alloc] initWithRootViewController:rootViewController] autorelease];

    [window addSubview:rootController.view];
    [self.window makeKeyAndVisible];
    return YES;
}

在 RootViewController 中：

- (void)viewDidLoad {
  [super viewDidLoad];

  LoginViewController *loginViewController = [[[LoginViewController alloc] initWithNibName:@"LoginView" bundle:nil] autorelease];
  loginViewController.delegate = self;

  loginViewController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
  [self presentModalViewController:loginViewController animated:YES];
}

- (void)loginViewControllerFinished {
  [self dismissModalViewControllerAnimated:YES];

  // Here we are closing one modal. And showing another after that.
  ABPeoplePickerNavigationController *peoplePicker = [[[ABPeoplePickerNavigationController alloc] init] autorelease];
  peoplePicker.peoplePickerDelegate = self;
  [self presentModalViewController:peoplePicker animated:YES];
}

在登录视图控制器中：

// Make sure LoginViewController has delegate property in header.
// @property (nonatomic, assign) id delegate;
// And put this in implementation (.m) file. @synthesize delegate.
// Don't put release for delegate, since it's not retained. It's only 'assigned'.

- (void)done {
  // Call this when you want to close loginViewController.
  [delegate loginViewControllerFinished];
}

希望这会有所帮助。

【讨论】：