编辑：在 iOS5+ 中执行此操作的“正确”机制是使用 – dismissViewControllerAnimated:completion: 方法，并从完成块显示顺序视图控制器。
模态显示的视图控制器将在模态关闭动画完成后调用其 viewDidDisappear:animated: 方法。 AFIK 这是唯一可以挂钩以启动后续 presentModalViewController:animated: 调用的地方。
我有一个用于呈现模态视图控制器的类，它通过在解除完成后对呈现视图控制器的回调来实现您正在寻找的逻辑。要使用这个类，只需分配/初始化一个实例并使用普通的 presentViewController:animated: 调用来呈现。在呈现视图控制器上实现以下方法：
- (void) modalViewControllerDidDismiss:(UIViewController *)modalViewController
这将在模态视图控制器消失后立即调用，此时您可以呈现一个新的模态视图控制器。
还有一件好事——因为这个类是 UINavigationController 的一个特化，你可以根据需要配置导航栏的开/关。该类还具有内置逻辑，可以根据需要显示关闭按钮。
这是类定义：
@protocol TSModalViewControllerDelegate
- (void) modalViewControllerDidDismiss: (UIViewController*) modalViewController;
@end
@interface TSModalViewController : UINavigationController
{
UIViewController* _originalParentViewController;
}
@property BOOL dismissButtonHidden;
- (id) initWithViewController: (UIViewController*) vc;
- (id) initWithClass: (Class) c;
- (id) initWithClass: (Class) c nibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil;
@end
以及类的实现：
@implementation TSModalViewController
@synthesize dismissButtonHidden;
- (id) initWithViewController: (UIViewController *)vc
{
return [super initWithRootViewController: vc];
}
- (id) initWithClass:(Class)c
{
UIViewController* vc = [[[c alloc] init] autorelease];
return [self initWithViewController: vc];
}
- (id) initWithClass: (Class) c nibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
UIViewController* vc = [[[c alloc] initWithNibName:nibNameOrNil bundle:nibBundleOrNil] autorelease];
return [self initWithViewController: vc];
}
- (void) viewDidAppear: (BOOL) animated
{
[super viewDidAppear: animated];
[_originalParentViewController release];
_originalParentViewController = [self.parentViewController retain];
if (!self.dismissButtonHidden)
{
UIBarButtonItem* dismissButton = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem: UIBarButtonSystemItemStop
target: self
action: @selector(onDismiss:)] autorelease];
UIViewController* rootViewController = [self.viewControllers objectAtIndex:0];
rootViewController.navigationItem.leftBarButtonItem = dismissButton;
self.navigationBarHidden = NO;
}
}
- (void) viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear: animated];
if ( [_originalParentViewController respondsToSelector: @selector(modalViewControllerDidDismiss:)] )
{
[_originalParentViewController performSelector: @selector(modalViewControllerDidDismiss:) withObject: self];
}
}
- (void) dismissModalViewControllerAnimated:(BOOL)animated
{
return [self.parentViewController dismissModalViewControllerAnimated: animated];
}
- (void) onDismiss: (id) sender
{
[self.parentViewController dismissModalViewControllerAnimated: YES];
}
- (void) didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
- (void) viewDidUnload
{
[super viewDidUnload];
}
- (void)dealloc
{
[_originalParentViewController release];
[super dealloc];
}
@end
并且，这是你如何使用它（在一些普通视图控制器的上下文中）：
- (void) onShowIt:(id)sender
{
TSModalViewController* mvc = [[[TSModalViewController alloc] initWithClass: [MyModalViewController class] nibName: @"MyModalViewController" bundle:nil] autorelease];
mvc.dismissButtonHidden = YES; // set to no if you don't want an "automatic" close button
[self presentModalViewController: mvc animated: YES];
}
还有，这里是解除回调方法，它提供了一个新的模态视图控制器：
- (void) modalViewControllerDidDismiss:(UIViewController *)modalViewController
{
MyModalViewController* vc = [[[MyModalViewController alloc] initWithNibName: @"MyModalViewController" bundle:nil] autorelease];
vc.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
TSModalViewController* mvc = [[[TSModalViewController alloc] initWithViewController: vc] autorelease];
[self presentModalViewController: mvc animated: YES];
}