可以使用popViewControllerAnimated传递数据吗？

Question

我遇到了一个有趣的问题,我有主ViewController让我用navController调用他MainVC,我正在从他执行performSegueWithIdentifier到我的第二个ViewController让我们称他为SecVC.所以,当我试图做popViewControllerAnimated我想将一些数据从SecVC传递给MainVc ..我知道我可以用appDelegate Param或单人类来做,但我的问题是:我能用更优雅的解决方案做到吗？就像我使用prepareForSegue并使用本地参数..

谢谢...

Answer 1

最好的方法是使用委托.

//SecVCDelegate.h

#import <Foundation/Foundation.h>

@protocol SecVSDelegate <NSObject>

@optional
- (void)secVCDidDismisWithData:(NSObject*)data;
@end

//SecVC.h

#import <UIKit/UIKit.h>
#import "SecVSDelegate.h"

@interface SecVC : UIViewController

/** Returns the delegate */
@property (nonatomic, assign)   id<SecVSDelegate> delegate;

@end

//SecVC.M

...

- (void) dealloc
{
...
delegate = nil
...
}

什么时候popViewControllerAnimated,就在它之后(或之前),你这样做

if(_delegate && [_delegate respondsToSelector:@selector(secVCDidDismisWithData:)])
{
[_delegate secVCDidDismisWithData:myDataObject];
}

在MainVC中,您必须确保实现委托函数 //MainVC.m

- (void)secVCDidDismisWithData
{
//do whatever you want with the data
}

要避免任何警告,您必须告诉MainVC类如下所示实现委托:

//MainVC.h

#import "SecVCDelegate.h"
...
@interface MainVC : UIViewController <SecVCDelegate>
...
secVCInstance.delegate = self;
[self.navigationController pushViewController:secVCInstance]; 
...

Answer 2

虽然我同意最好的选择是使用Delegate,但如果任何人正在寻找不同的东西,他可以使用NSNotificationCenter作为替代.

在MainVC的viewDidLoad中:

- (void)viewDidLoad
{

    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(recvData:)
                                             name:@"SecVCPopped"
                                           object:nil];
}

相加法recvData在MainVC.m

- (void) recvData:(NSNotification *) notification
{

    NSDictionary* userInfo = notification.userInfo;
    int messageTotal = [[userInfo objectForKey:@"total"] intValue];
    NSLog (@"Successfully received data from notification! %i", messageTotal);
}

现在在SecVC中,在弹出之前,添加此行

NSMutableDictionary* userInfo = [NSMutableDictionary dictionary];
[userInfo setObject:[NSNumber numberWithInt:messageTotal] forKey:@"total"];

NSNotificationCenter* nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:@"SecVCPopped" object:self userInfo:userInfo];