iphone - 如何符合 UITabBarControllerDelegate

Question

我有一个基于标签栏的应用程序并执行以下操作以获取对应用程序委托(delegate)的引用:

MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

然后给出这个警告:

warning: type 'id <UIApplicationDelegate>' does not conform to the 'UITabBarControllerDelegate' 

我的应用程序委托(delegate) header 如下所示:

#import <UIKit/UIKit.h>

@interface MyAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate>     {
UIWindow *window;
UITabBarController *tabBarController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;

@end

.m 文件中仅有的方法是 applicationDidFinishLaunching 和 dealloc。我还需要什么来遵守协议(protocol)？

Answer 1

这是静态警告。说明[[UIApplication sharedApplication] delegate]的返回类型不符合tab bar delegate协议(protocol)，是的。

转换从 [[UIApplication sharedApplication] delegate] 返回的值来消除警告:

MyAppDelegate *appDelegate = (MyAppDelegate*)[[UIApplication sharedApplication] delegate];