iphone - 如何从自定义 Controller 操作引用 AppDelegate 实例变量？

Question

我希望能够(作为 Controller 的学习练习)在我设置的初始 View 上有一个按钮，然后如果您单击该按钮，则会发生一个操作，将 View 从 View 1 交换到 View 2。我不知道你怎么会这样？请参阅下面的代码部分，我想在其中插入执行此操作的代码。

任何人都可以发布我需要的代码吗？ (即，它将涵盖如何引用我在 AppDelegate 中建立的变量)。如果我给自己做的这个练习有什么缺陷，请告诉我。谢谢。

AppDelegate *.h

#import <UIKit/UIKit.h>
@class gregsController;
@class Gregs2ndController;  

@interface windowsBasedAppDelegate : NSObject <UIApplicationDelegate> {
    UIWindow *window;
    gregsController *viewController;
    Gregs2ndController *view2Controller;

}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet gregsController *viewController;
@property (nonatomic, retain) IBOutlet Gregs2ndController *view2Controller;

@end

AppDelegate *.m

#import "windowsBasedAppDelegate.h"
#import "gregsController.h"
#import "Gregs2ndController.h"

@implementation windowsBasedAppDelegate

@synthesize window;
@synthesize viewController;
@synthesize view2Controller;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    // Override point for customization after application launch.
    NSLog(@"windowsBasedAppDelegate - didFinishLaunchingWithOptions");

    //[self.window addSubview:viewController.view];
    [self.window addSubview:view2Controller.view];
    [self.window makeKeyAndVisible];

    return YES;
}

自定义 Controller *.m

#import "gregsController.h"
@implementation gregsController
- (IBAction)logSomething {
    NSLog(@"About to switch views");
    [self.view removeFromSuperview];

        // *** HOW DO I REFERENCE view2Controller AND PUT THIS AS THE VIEW  ???? ****

    NSLog(@"Finished switching views");
}

Answer 1

您可以通过UIApplication在任何您想要的地方获得对您的应用程序委托(delegate)的引用。单例:

#import "gregsController.h"
@implementation gregsController
- (IBAction)logSomething {
    NSLog(@"About to switch views");
    [self.view removeFromSuperview];

    // *** HOW DO I REFERENCE view2Controller AND PUT THIS AS THE VIEW  ???? ****
    // Like this:
    windowsBasedAppDelegate* appDelegate = (windowsBasedAppDelegate*)[[UIApplication sharedApplication] delegate];
    [appDelegate.window addSubview:appDelegate.view2Controller.view];

    NSLog(@"Finished switching views");
}