Question

我正在 appDelegate 中创建NSNotification。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkRegister:) name:@"checkRegister" object:nil];

    return YES;
}

-(void)checkRegister:(NSNotification *) notification{

//Some code

}

我在其他课程上发布通知：

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"DONE. Received Bytes: %d", [webData length]);
    NSString *theXML = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding];
    NSLog(@"%@",theXML);
    [theXML release];

    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithData: webData];
    [xmlParser setDelegate:self];
    [xmlParser setShouldResolveExternalEntities: YES];
    [xmlParser parse];
    [xmlParser release];

    [connection release];
    [webData release];

    if(strUserName != NULL)
        [[NSNotificationCenter defaultCenter] postNotificationName:@"checkRegister" object:nil];


}

问题是从不调用checkRegister。

Answer 1

@"checkRegister"通知的目的是什么？在发布通知之前，您if(strUserName != NULL)检查了if，但我没看到您在strUserName设置了NSLog(@"%@", strUserName)一定要试试strUserName。我很确定它是空的。如果NSXMLParser来自您解析的XML数据，则应在XML解析代码之后发布通知，该代码将在您实现的[xmlParser parse]委托方法中。这将是one of these you use.

if(strUserName != NULL) [[NSNotificationCenter defaultCenter] postNotificationName:@"checkRegister" object:nil];没有阻止，所以你的

xmlParser

在postNoticationName:完成解析之前将调用

，因此，你的strUserName尚未设置，这就是它为零的原因而你的[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkRegister:) name:@"checkRegister" object:nil];将不会被调用

编辑：

把你的

application:didFinishLaunchingWithOptions:

在- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkRegister:) name:@"checkRegister" object:nil]; self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease]; // Override point for customization after application launch. if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) { self.mainViewController = [[[MainViewController alloc] initWithNibName:@"MainViewController_iPhone" bundle:nil] autorelease]; } else { self.mainViewController = [[[MainViewController alloc] initWithNibName:@"MainViewController_iPad" bundle:nil] autorelease]; } self.window.rootViewController = self.mainViewController; [self.window makeKeyAndVisible]; return YES; }的最顶部，您很可能在注册通知之前在主视图中发布通知，例如

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        self.mainViewController = [[[MainViewController alloc] initWithNibName:@"MainViewController_iPhone" bundle:nil] autorelease];
    } else {
        self.mainViewController = [[[MainViewController alloc] initWithNibName:@"MainViewController_iPad" bundle:nil] autorelease];
    }
    self.window.rootViewController = self.mainViewController;
    [self.window makeKeyAndVisible];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkRegister:) name:@"checkRegister" object:nil];
    return YES;
}

将起作用，而

MainControllerView

如果您使用viewDidLoad {{1}}方法完成数据加载，

将无效。

NSNotification没有调用选择器

1 个答案: