在两个类之间共享对象 [英] Sharing an object between two classes

问题描述

我正在为OS X开发一个应用程序，我遇到了问题。

I'm developing an app for OS X and I got stuck with a problem.

应用程序的结构是：

• AppDelegate：主要操作发生在MainMenu.xib。

• AppDelegate: where the main actions take place from MainMenu.xib. It's also where the main window is created.

SettingsWindowController：其中设置窗口通过SettingsWindow.xib的接口定义。

SettingsWindowController: where a settings window is defined with interface from SettingsWindow.xib.

我创建了一个协议SettingsWindowProtocol委派这两个类。

I created a protocol SettingsWindowProtocol to delegate those two classes.

我创建了一个类dbHandler，

I created one more class dbHandler which is initialized as an obj dbh in AppDelegate.

在SettingsWindowProtocol中，我创建了一个方法来发送对象，这个方法在SettingsWindowControl对象为null。

In SettingsWindowProtocol I created a method to send the object but after I call this method in SettingsWindowControl the object is null.

问题是我如何在两个不同的类共享同一个对象？

The question is how I share in two different classes the same object ?

与问题相关的几个代码块：

A few blocks of code related to question:

AppDelegate.h：

AppDelegate.h:

#import "dbHandler.h"    

...

@property (retain) dbHandler *dbh;
@interface AppDelegate : NSObject <SettingsWindowControllerProtocol>

-(dbHandler*)sendDBobject;

AppDelegate.m：

AppDelegate.m:

...
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{   
    dbh = [[dbHandler alloc]init];
    ...
}

- (IBAction)settingsButton:(id)sender {
    if(!settingsWindowController){
        settingsWindowController = [[SettingsWindowController alloc] initWithWindowNibName:@"SettingsWindow"];
    }

    [settingsWindowController showWindow:self];
    settingsWindowController.delegate = self;
}

-(dbHandler*)sendDBobject{
    return dbh;
}

SettingsWindowController.h：

SettingsWindowController.h :

#import "dbHandler.h"

@protocol SettingsWindowControllerProtocol<NSObject>
    -(dbHandler*)sendDBobject;
@end

@interface SettingsWindowController : NSWindowController

@property (assign) id<SettingsWindowControllerProtocol> delegate;

@property (retain) dbHandler* dbh;

@end

SettingsWindowController.m：

SettingsWindowController.m:

- (void)windowDidLoad
{
    dbh = [delegate sendDBobject];
    [super windowDidLoad];
    NSLog(@"settings string returned: %@",[dbh returnString]);
}

推荐答案

从您的应用程序的任何地方通过 NSApp委托方法。因此，为了得到 dbh 对象，您只需这样做：

You can access your app delegate from anywhere in your app via the NSApp delegate method. So to get the dbh object, you would just do something like this:

AppDelegate *appDelegate = [NSApp delegate];
dbh = appDelegate.dbh;

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