iphone - 模态视图 Controller 内使用 UINavigationController 进行内存管理

Question

我正在尝试显示包含导航 Controller 的模态视图 Controller 。但我不知道在哪里释放 Controller 。通常，我会在显示 Controller 后释放它，但这在这里不起作用；据推测这与导航 Controller 有关。任何帮助都会很棒!这是有问题的代码:

-(IBAction)displayCreateModifyExerciseViewController:(id)sender {    
    CreateModifyExerciseViewController *controller = [[CreateModifyExerciseViewController alloc] initWithNibName:@"CreateModifyExerciseView"
                                                                                                          bundle:nil];
    controller.delegate = self;
    controller.title = @"Create Exercise";
    UINavigationController *modalNavController = [[[UINavigationController alloc] initWithRootViewController:controller] autorelease];
    modalNavController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    controller.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Save"
                                                                                    style:UIBarButtonItemStyleDone
                                                                                   target:controller
                                                                                   action:@selector(done:)];
    [self presentModalViewController:modalNavController animated:YES];
    //I want to say [controller release];
    //              [modalNavController release];
    //But that causes a crash because controller ends up dealloc-ing.
}

Answer 1

您正在自动释放 modalNavController 以及专门释放它，这就是导致它过早释放的原因。要么自动释放，要么专门释放，但尽量不要同时进行。

所以:

CreateModifyExerciseViewController *controller = [[[CreateModifyExerciseViewController alloc] initWithNibName:@"CreateModifyExerciseView" bundle:nil] autorelease];
controller.delegate = self;
controller.title = @"Create Exercise";
UINavigationController *modalNavController = [[[UINavigationController alloc] initWithRootViewController:controller] autorelease]; // <-- you originally autorelease here
modalNavController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
controller.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] 
                         initWithTitle:@"Save" 
                                 style:UIBarButtonItemStyleDone
                                target:controller
                                action:@selector(done:)] autorelease]; // <-- this was leaking in your code -- needs to be autoreleased
[self presentModalViewController:modalNavController animated:YES];
// Don't release now because everything was autoreleased

或者专门发布所有内容:

CreateModifyExerciseViewController *controller = [[CreateModifyExerciseViewController alloc] initWithNibName:@"CreateModifyExerciseView" bundle:nil];
controller.delegate = self;
controller.title = @"Create Exercise";
UINavigationController *modalNavController = [[UINavigationController alloc] initWithRootViewController:controller]; // <-- you originally autorelease here
modalNavController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
controller.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] 
                         initWithTitle:@"Save" 
                                 style:UIBarButtonItemStyleDone
                                target:controller
                                action:@selector(done:)] autorelease]; // <-- this was leaking in your code -- needs to be autoreleased
[self presentModalViewController:modalNavController animated:YES];
// Now we specifically release the controllers because the call to -presentModalViewController:animated: owns them
[controller release];
[modalNavController release];