objective-c - 如何从应用程序委托(delegate)访问 View Controller 变量......反之亦然？

Question

我希望 View Controller 能够访问应用委托(delegate)中的 dog。

我希望应用委托(delegate)能够访问 View Controller 中的鼠标。

---

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{
    int mouse;  // <----------------
}
@end

---

- (void)viewDidLoad
{
    [super viewDidLoad];

    mouse = 12;  // <-------------------

    NSLog(@"viewDidLoad %d", dog); // <---------------
}

---

#import <UIKit/UIKit.h>

@class ViewController;

@interface AppDelegate : UIResponder <UIApplicationDelegate>
{
    int dog;  // <---------------
}
@property (strong, nonatomic) UIWindow *window;

@property (strong, nonatomic) ViewController *viewController;

@end

---

- (void)applicationWillResignActive:(UIApplication *)application
{
    NSLog(@"applicationWillResignActive %d", mouse); // <--------------
}

---

 - (void)applicationDidBecomeActive:(UIApplication *)application
{
    dog = 77; // <---------------------

    NSLog(@"applicationDidBecomeActive");
}

Answer 1

第 1 部分:在 ViewController.h 中:

-(int)mouse;  //add this before the @end

在 ViewController.m 中，添加这个方法:

-(int)mouse
{
    return mouse;
}

要从 AppDelegate 访问鼠标，请使用 self.viewController.mouse例如；

NSLog(@"ViewController mouse: %i", self.viewController.mouse);

第二部分:

在 AppDelegate.h 中:

-(int)dog;  //add this before the @end

在 AppDelegate.m 中，添加这个方法:

-(int)dog
{
    return dog;
}

在 ViewController.m 中:

#import "AppDelegate.h"

要从 ViewController 访问狗，请使用:

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSLog(@"dog from AppDelegate: %i", [appDelegate dog]);  //etc.