滾動視圖中的Iphone Web視圖

Question

我有一個小應用程序與一些細節控制器。詳細控制器是把滾動視圖內的Web視圖： 下面是詳細視圖控制器的代碼：

- (void)loadScrollViewWithPage:(int)page 

{

if (page < 0) 
    return; 
if (page >= detailTotalJobs) 
    return; 

// replace the placeholder if necessary 
SearchJobDetailWebViewController *controller = [viewControllers objectAtIndex:page]; 
if ((NSNull *)controller == [NSNull null]) 
{ 



    NSLog(@"Vytvaram web controller: %d", page + 1); 

    if (detailJobIndex == page) { 

     controller = [[SearchJobDetailWebViewController alloc] initWithNibName:@"SearchJobDetailWebViewController" bundle:nil page:page url:detailExportUrl]; 
     [viewControllers replaceObjectAtIndex:page withObject:controller]; 
     [controller release]; 

    } else if (detailJobIndex + 1 == page) { 

     controller = [[SearchJobDetailWebViewController alloc] initWithNibName:@"SearchJobDetailWebViewController" bundle:nil page:page url:detailNextExportUrl]; 
     [viewControllers replaceObjectAtIndex:page withObject:controller]; 
     [controller release]; 

    } else { 

     [self performSelector:@selector(downloadData:) withObject:[NSNumber numberWithInt:page] afterDelay:0.1]; 
     //[self downloadData:[NSNumber numberWithInt:page]]; 

     controller = [[SearchJobDetailWebViewController alloc] initWithNibName:@"SearchJobDetailWebViewController" bundle:nil page:page url:nextArray.exportUrl]; 
     [viewControllers replaceObjectAtIndex:page withObject:controller]; 
     [controller release]; 

    } 

} 

// add the controller's view to the scroll view 
if (controller.view.superview == nil) 
{ 

    CGRect frame = scrollView.frame; 
    frame.origin.x = frame.size.width * page; 
    frame.origin.y = 0; 
    controller.view.frame = frame; 
    [scrollView addSubview:controller.view]; 

    //NSDictionary *numberItem = [self.contentList objectAtIndex:page]; 
    //controller.numberImage.image = [UIImage imageNamed:[numberItem valueForKey:ImageKey]]; 
    //controller.myLabel.text = @"Test"; 
} 

}

- (void)scrollViewDidScroll:(UIScrollView *)sender 

{// 我們不不需要UIPageControl和滾動代理之間的「反饋循環」 //其中滾動事件是從用戶點擊頁面控制觸發從 //委託方法更新。當使用頁面控件時，我們使用布爾值來禁用委託邏輯。 if（pageControlUsed） //不執行任何操作 - 滾動是從頁面控件啓動的，而不是用戶拖動 返回; }

// Switch the indicator when more than 50% of the previous/next page is visible 
CGFloat pageWidth = scrollView.frame.size.width; 
int page = floor((scrollView.contentOffset.x - pageWidth/2)/pageWidth) + 1; 
pageControl.currentPage = page; 

NSString *detailTitleText = [NSString stringWithFormat:@"%d/%d", page + 1, detailTotalJobs]; 
[self setTitle:detailTitleText]; 
//[detailTitleText release]; 

// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling) 
[self loadScrollViewWithPage:page - 1]; 
[self loadScrollViewWithPage:page]; 
[self loadScrollViewWithPage:page + 1]; 

// A possible optimization would be to unload the views+controllers which are no longer visible 

}

代碼由蘋果頁面控制的啓發。

問題是在這裏：

if (detailJobIndex == page) { 

     controller = [[SearchJobDetailWebViewController alloc] initWithNibName:@"SearchJobDetailWebViewController" bundle:nil page:page url:detailExportUrl]; 
     [viewControllers replaceObjectAtIndex:page withObject:controller]; 
     [controller release]; 

    } else if (detailJobIndex + 1 == page) { 

     controller = [[SearchJobDetailWebViewController alloc] initWithNibName:@"SearchJobDetailWebViewController" bundle:nil page:page url:detailNextExportUrl]; 
     [viewControllers replaceObjectAtIndex:page withObject:controller]; 
     [controller release]; 

    } else { 

     [self performSelector:@selector(downloadData:) withObject:[NSNumber numberWithInt:page] afterDelay:0.1]; 
     //[self downloadData:[NSNumber numberWithInt:page]]; 

     controller = [[SearchJobDetailWebViewController alloc] initWithNibName:@"SearchJobDetailWebViewController" bundle:nil page:page url:nextArray.exportUrl]; 
     [viewControllers replaceObjectAtIndex:page withObject:controller]; 
     [controller release]; 

    } 

第一部分，如果工作的第二部分正確，因爲我對第一個網頁視圖和第二Web視圖的數據。

但是，如果有問題的最後一部分。當我從第二個Web視圖滾動到第三個Web視圖時，滾動視圖顯示空白頁面。下一頁正常工作。 問題在哪裏？

Answer 1

只需在調試模式中的大括號中放置一個斷點。
控制器是否爲零？ 檢查您的自定義init方法。

如果出現問題，是否返回零？

[self = super initWithNibName..................]; 
if (!self) return nil; 

// some inits 

return self; 

如果這樣做並且控制器爲零，請檢查您的URL並將其試用到Web瀏覽器中。它顯示嗎？

你如何填寫你的webView？填充時是否返回錯誤？沒有編碼問題返回？

那麼，一些代碼將有所幫助，但這些跡象是最常見的問題，你可以有。