更新導航欄

Question

我所做的一切都是當用戶翻頁時更新導航欄。以下是我的代碼

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController 
    viewControllerBeforeViewController:(UIViewController *)viewController { 

contentViewController = [[ContentViewController alloc] initWithPDF:PDFDocument]; 

currentIndex = [modelArray indexOfObject:[(ContentViewController *)viewController page]]; 

if (currentIndex == 0) { 

    return nil; 
} 

contentViewController.page = [modelArray objectAtIndex:currentIndex - 1]; 

[self updateNavigationBar]; 

return contentViewController; 

} 

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController 
    viewControllerAfterViewController:(UIViewController *)viewController { 

contentViewController = [[ContentViewController alloc] initWithPDF:PDFDocument]; 

//get the current page 
currentIndex = [modelArray indexOfObject:[(ContentViewController *)viewController page]]; 

if (currentIndex == totalPages - 1) { 

    return nil; 
} 

contentViewController.page = [modelArray objectAtIndex:currentIndex + 1]; 

[self updateNavigationBar]; 

return contentViewController; 

} 

-(void) updateNavigationBar{ 

if (CGPDFDocumentGetNumberOfPages(PDFDocument) > 1) { 
    title = [NSString stringWithFormat:@"Page %u of %u", currentIndex - 1, CGPDFDocumentGetNumberOfPages(PDFDocument)]; 
} else if ((CGPDFDocumentGetNumberOfPages(PDFDocument) < 1) { 


title = [NSString stringWithFormat:@"Page %u of %u", currentIndex + 1, CGPDFDocumentGetNumberOfPages(PDFDocument)]; 

} 

但似乎它不工作，我可以翻頁但無法更新導航欄。

，這是導航欄

_navBar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, 45)]; 

_navBar.tintColor = [UIColor colorWithRed:243.0/255.0 green:164.0/255.0 blue:0.0/255.0 alpha:1.0]; 

title = [[UINavigationItem alloc] initWithTitle:[NSString stringWithFormat: 
                    @"Page %u of %u", 
                    currentIndex, 
                    CGPDFDocumentGetNumberOfPages(PDFDocument)]]; 
[_navBar pushNavigationItem:title animated:NO]; 

請幫的代碼。

欣賞它。

謝謝。

Answer 1

更新導航欄被更新的導航項目的完成：

_navBar.topItem.title = @"Custom title"; 
[_navBar pushNavigationItem:_navBar.topItem animated:NO];