相关疑难解决方法(0)

我在尝试更改popoverController中导航控制器的颜色时遇到问题.
我正在尝试做这样的事情:

if (self.popoverController == nil) {
    ArtistsViewController *artistsViewController = 
    [[ArtistsViewController alloc]      
     initWithNibName:@"ArtistsViewController" 
     bundle:[NSBundle mainBundle]]; 

    artistsViewController.navigationItem.title = @"Artists";
    UINavigationController *navController = 
    [[UINavigationController alloc] 
     initWithRootViewController:artistsViewController];


    UIPopoverController *popover = 
    [[UIPopoverController alloc] 
     initWithContentViewController:artistsViewController.navigationController];
    artistsViewController.navigationController.navigationBar.tintColor=[UIColor greenColor];

    popover.delegate = self;
    [artistsViewController release];
    [navController release];

    self.popoverController = popover;
    [popover release];
}

[self.popoverController 
 presentPopoverFromBarButtonItem:sender                                    
 permittedArrowDirections:UIPopoverArrowDirectionAny 
 animated:YES];

但它不起作用.有什么建议？