Possible Duplicate:
Call Function in Underlying ViewController as Modal View Controller is Dismissed

我几乎尝试了所有方法。这是我尝试过的:

-(void)viewWillAppear:(BOOL)animated
{

NSLog(@"Test");

}

-(void)viewDidAppear:(BOOL)animated
{

NSLog(@"Test");

}

-(void)viewDidLoad
{

NSLog(@"Test");

}

当模态视图 Controller 被解除时，为什么这些都不能在我的父 View Controller 中工作？我怎样才能让它工作？

最佳答案

这个答案被重写/扩展以解释 3 种最重要的方法 (@galambalazs)

1。 block

最简单的方法是使用回调 block .如果您只有一个监听器(父 View Controller )对解雇感兴趣，这很好。您甚至可以通过事件传递一些数据。

在MainViewController.m

SecondViewController* svc = [[SecondViewController alloc] init];
svc.didDismiss = ^(NSString *data) {
    // this method gets called in MainVC when your SecondVC is dismissed
    NSLog(@"Dismissed SecondViewController");
};
[self presentViewController:svc animated:YES completion:nil];

在SecondViewController.h

@interface MainViewController : UIViewController
    @property (nonatomic, copy) void (^didDismiss)(NSString *data);
    // ... other properties
@end

在SecondViewController.m

- (IBAction)close:(id)sender 
{
    [self dismissViewControllerAnimated:YES completion:nil];

    if (self.didDismiss) 
        self.didDismiss(@"some extra data");
}

2。委派

Delegation是 Apple 推荐的模式:

Dismissing a Presented View Controller

If the presented view controller must return data to the presenting view controller, use the delegation design pattern to facilitate the transfer. Delegation makes it easier to reuse view controllers in different parts of your app. With delegation, the presented view controller stores a reference to a delegate object that implements methods from a formal protocol. As it gathers results, the presented view controller calls those methods on its delegate. In a typical implementation, the presenting view controller makes itself the delegate of its presented view controller.

MainViewController

在MainViewController.h

@interface MainViewController : UIViewController <SecondViewControllerDelegate>
    - (void)didDismissViewController:(UIViewController*)vc;
    // ... properties
@end

MainViewController.m 中的某处(呈现)

SecondViewController* svc = [[SecondViewController alloc] init];
svc.delegate = self;
[self presentViewController:svc animated:YES completion:nil];

MainViewController.m 中的其他地方(被告知解雇)

- (void)didDismissViewController:(UIViewController*)vc
{
    // this method gets called in MainVC when your SecondVC is dismissed
    NSLog(@"Dismissed SecondViewController");
}

SecondViewController

在SecondViewController.h

@protocol SecondViewControllerDelegate <NSObject>
- (void)didDismissViewController:(UIViewController*)vc;
@end

@interface SecondViewController : UIViewController
@property (nonatomic, weak) id<SecondViewControllerDelegate> delegate;
// ... other properties
@end

SecondViewController.m

[self.delegate didDismissViewController:self];
[self dismissViewControllerAnimated:YES completion:nil];

(注意:带有 didDismissViewController: 方法的协议(protocol)可以在整个应用程序中重复使用)

3。通知

另一种解决方案是发送 NSNotification .这也是一种有效的方法，如果您只想通知解雇而不传递太多数据，它可能比委托(delegate)更容易。但它的主要用例是当您想要 多个监听器 用于解除事件(不仅仅是父 View Controller )时。

但请确保在完成后始终将自己从 NSNotificationCentre 中移除!否则，即使在您被解除分配后，您也可能会因被要求通知而崩溃。 [编者注]

在MainViewController.m

- (IBAction)showSecondViewController:(id)sender 
{
    SecondViewController *secondVC = [[SecondViewController alloc] init];
    [self presentViewController:secondVC animated:YES completion:nil];

    // Set self to listen for the message "SecondViewControllerDismissed"
    // and run a method when this message is detected
    [[NSNotificationCenter defaultCenter] 
     addObserver:self
     selector:@selector(didDismissSecondViewController)
     name:@"SecondViewControllerDismissed"
     object:nil];
}

- (void)dealloc
{
    // simply unsubscribe from *all* notifications upon being deallocated
    [[NSNotificationCenter defaultCenter] removeObserver:self];
} 

- (void)didDismissSecondViewController 
{
    // this method gets called in MainVC when your SecondVC is dismissed
    NSLog(@"Dismissed SecondViewController");
}

在SecondViewController.m

- (IBAction)close:(id)sender 
{
    [self dismissViewControllerAnimated:YES completion:nil];

    // This sends a message through the NSNotificationCenter 
    // to any listeners for "SecondViewControllerDismissed"
    [[NSNotificationCenter defaultCenter] 
     postNotificationName:@"SecondViewControllerDismissed" 
     object:nil userInfo:nil];
}

希望这会有所帮助!

关于iphone - 如何检测父 View Controller 中模态视图 Controller 的解除？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10387039/