无法显示MBProgressHUD

Question

在这里说使用MBProgressHUD很容易.但我做不到.

这是我的代码:

- (IBAction)save{
    HUD = [[MBProgressHUD alloc] initWithView:self.navigationController.view];
    [self.navigationController.view addSubview:HUD];
    HUD.delegate = self;
    [HUD show:YES];

    NSString *title = [page stringByEvaluatingJavaScriptFromString:@"document.title"];
    SavePageAs *savePage = [[SavePageAs alloc] initWithUrl:self.site directory:title];
    [savePage save];
    [HUD hide:YES];
}

savePage save方法运行期间未显示进度指示器,但在页面完全保存后显示(指示器显示不到1秒).

我也尝试过这种方式:

- (IBAction)save {

    HUD = [[MBProgressHUD alloc] initWithView:self.navigationController.view];
   [self.navigationController.view addSubview:HUD];

   HUD.delegate = self;
   HUD.labelText = @"Saving...";

   [HUD showWhileExecuting:@selector(performFetchOnMainThread) onTarget:self withObject:nil animated:YES];
}

- (void) savingPage{
    NSString *title = [page stringByEvaluatingJavaScriptFromString:@"document.title"];
    SavePageAs *savePage = [[SavePageAs alloc] initWithUrl:self.site directory:title];
    [savePage save];
}

-(void) performFetchOnMainThread    {
    [self performSelectorOnMainThread:@selector(savingPage) withObject:nil waitUntilDone:YES];
}

但仍然没有运气.有人让我知道我在这里缺少的地方吗？

PS:savePage save将所有网站内容保存到本地目录.我希望一旦保存完成,progressHUD就会消失.

谢谢

Answer 1

尝试的分配HUD上viewWillAppear:,而不是-(IBAction)save因为有时分配占据了整个时间和时它分配整个任务完成.

复制以下链接viewWillAppear:和从中删除-(IBAction)save

 HUD = [[MBProgressHUD alloc] initWithView:self.navigationController.view];
 [self.navigationController.view addSubview:HUD];

 HUD.delegate = self;
 HUD.labelText = @"Saving...";

编辑:保持分配viewWillAppear:和更改代码,如下所示:

- (IBAction)save {
    [NSThread detachNewThreadSelector:@selector(showHUD) withObject:nil];
    [self performSelectorOnMainThread:@selector(savingPage) withObject:nil waitUntilDone:YES];
}

- (void) savingPage{
    NSString *title = [page stringByEvaluatingJavaScriptFromString:@"document.title"];
    SavePageAs *savePage = [[SavePageAs alloc] initWithUrl:self.site directory:title];
    [savePage save];
    [HUD hide:YES];
}

-(void)showHUD {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
   [HUD show:YES];
   [pool release];
}

这将做的是创建一个单独的线程来显示HUD,因为savePage方法正在使用主线程.

如果这也不起作用,那么只需waitUntilDone:YES改为waitUntilDone:NO

注意:根据Apple文档

要点:如果使用自动引用计数(ARC),则无法直接使用自动释放池.相反,您使用@autoreleasepool块代替.例如,代替:

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init;
// Code benefitting from a local autorelease pool.
[pool release];

你会写:

@autoreleasepool {
    // Code benefitting from a local autorelease pool.
}

@autoreleasepool块比直接使用NSAutoreleasePool实例更有效; 即使您不使用ARC,也可以使用它们.

希望这可以帮助.