iPhone程序运行流程浅谈

1. 和大多数语言一样，每一个iPhone应用也都是从主函数开始运行，它的main函数都在XCode的Other Reasource逻辑目录下。

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UIApplicationMain(argc, argv, nil, nil);

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UIApplicationMain(argc, argv, nil, nil);

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@interface testSDKAppDelegate : NSObject <UIApplicationDelegate> {

UIWindow *window;
testViewController *viewController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet testViewController *viewController;

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@interface testSDKAppDelegate : NSObject <UIApplicationDelegate> {
UIWindow *window;
testViewController *viewController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet testViewController *viewController;

@interface testSDKAppDelegate : NSObject <UIApplicationDelegate> {
UIWindow *window;
testViewController *viewController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet testViewController *viewController;

这样就可以在Interface Builder里连接，并且完成相应的初始化工作。

观察MainWindow.xib的** APP Delegate实例，Interface Builder已经为我们连接上了一个Window和一个Controller实例。

再看看** APP Delegate.m。

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

// Override point for customization after app launch.

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

return YES;

}

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

// Override point for customization after app launch.

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

return YES;
}

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

// Override point for customization after app launch.
[self.window addSubview:viewController.view];
[self.window makeKeyAndVisible];

return YES;
}

他在UIApplication的这个回调方法中，将Controller的视图加载到了Window上。

关于这个回调方法文档当中有这么一句话， It is called after your application has been launched and its main nib file has been loaded. 就是说在程序运行起来并且主nib文件完成加载后，这个委托方法将会被调用。

整个程序目前暂时不需要我们考虑的初始化流程就结束了， 在这之后，我们就可以加入我们程序的逻辑了。

由于时间仓促，如有疏漏还请大家指出。

希望本文可以帮到你。