I'm having a problem with trying to change the colour of my navigation controller inside my popoverController.
I'm trying to do something like this:
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];
but it doesn't work. any suggestions?
////////////////////////////////////////
////////////**SOLUTION**////////
////////////////////////////////////////
I'm gonna edit this post because i solved my problem and I think could be helpful share my solution here:
first of all, follow this sample:
http://mobiforge.com/designing/story/using-popoverview-ipad-app-development
When It is done go to step two.
The second step will be add a new popoverBackgroundViewClass:
Add new file in your project Objective class and call it 'CustomPopoverBackgroundView'
///////////////////////////////////////////////
////// CustomPopoverBackgroundView.h  /////////
///////////////////////////////////////////////
     #import < UIKit/UIKit.h >
     #import < UIKit/UIPopoverBackgroundView.h >
    @interface CustomPopoverBackgroundView : UIPopoverBackgroundView{
        UIPopoverArrowDirection direction;
        CGFloat offset;
    }
    @end
//////////////////////////////////////////////
////// CustomPopoverBackgroundView.m /////////
//////////////////////////////////////////////
    #import "CustomPopoverBackgroundView.h"
    @implementation CustomPopoverBackgroundView
     -  (void)layoutSubviews {
        [super layoutSubviews];
        CGFloat fullHeight = self.frame.size.height;
        CGFloat fullWidth = self.frame.size.width;
        CGFloat startingLeft = 0.0;
        CGFloat startingTop = 0.0;
        CGFloat arrowCoord = 0.0;
        UIImage *arrow;
        UIImageView *arrowView;
        switch (self.arrowDirection) {
            case UIPopoverArrowDirectionUp:
                startingTop += 13.0;
                fullHeight -= 13.0;
    //the image line.png will be the corner 
                arrow = [UIImage imageNamed:@"line.png"];
                arrowCoord = (self.frame.size.width / 2) - self.arrowOffset;
                arrowView = [[[UIImageView alloc] initWithFrame:CGRectMake(arrowCoord, 0, 13.0, 13.0)] autorelease];
                break;
            case UIPopoverArrowDirectionDown:
                fullHeight -= 13.0;
                arrow = [UIImage imageNamed:@"line.png"];
                arrowCoord = (self.frame.size.width / 2) - self.arrowOffset;
                arrowView = [[[UIImageView alloc] initWithFrame:CGRectMake(arrowCoord, fullHeight, 13.0, 13.0)] autorelease];
                break;
            case UIPopoverArrowDirectionLeft:
                startingLeft += 13.0;
                fullWidth -= 13.0;
                arrow = [UIImage imageNamed:@"line.png"];
                arrowCoord = (self.frame.size.height / 2) - self.arrowOffset;
                arrowView = [[[UIImageView alloc] initWithFrame:CGRectMake(0, arrowCoord, 13.0, 13.0)] autorelease];
                break;
            case UIPopoverArrowDirectionRight:
                fullWidth -= 13.0;
                arrow = [UIImage imageNamed:@"line.png"];
                arrowCoord = (self.frame.size.height / 2) - self.arrowOffset;
                arrowView = [[[UIImageView alloc] initWithFrame:CGRectMake(self.frame.size.width-13.0, arrowCoord, 13.0, 13.0)] autorelease];
                break;
        }
        //this image will be your background
        UIImage *bg = [[UIImage imageNamed:@"lineBack.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(8.0, 8.0, 8.0, 8.0)];
        UIImageView *imageView = [[[UIImageView alloc] initWithFrame:CGRectMake(startingLeft, startingTop, fullWidth, fullHeight)] autorelease];
        [imageView setImage:bg];
        [arrowView setImage:arrow];
        [self addSubview:imageView];
        [self addSubview:arrowView];
    }
    - (CGFloat) arrowOffset {
        return offset;
    }
    - (void) setArrowOffset:(CGFloat)arrowOffset {
        offset = arrowOffset;
        [self setNeedsLayout];
    }
    - (UIPopoverArrowDirection)arrowDirection {
        return direction;
    }
    - (void)setArrowDirection:(UIPopoverArrowDirection)arrowDirection {
        direction = arrowDirection;
        [self setNeedsLayout];
    }
    + (CGFloat)arrowHeight {
        return 30.0;
    }
    + (CGFloat)arrowBase {
        return 30.0;
    }
    + (UIEdgeInsets)contentViewInsets {
        return UIEdgeInsetsMake(30.0, 30.0, 30.0, 30.0);
    }
    @end
Third step:
When It is done add this line in 'PopOverExample1ViewController.m':
import the new class:
#import " CustomPopoverBackgroundView.h "
-(IBAction) showMovies:(id) sender {
    if (self.popoverController == nil) {
        MoviesViewController *movies = 
            [[MoviesViewController alloc] 
                initWithNibName:@"MoviesViewController" 
                         bundle:[NSBundle mainBundle]]; 
        UIPopoverController *popover = 
            [[UIPopoverController alloc] initWithContentViewController:movies]; 
        popover.delegate = self;
        [movies release];
//THIS IS THE LINE THAT YOU HAVE TO ADD
         popover.popoverBackgroundViewClass=[CustomPopoverBackgroundView class];
        self.popoverController = popover;
        [popover release];
    }
    [self.popoverController 
        presentPopoverFromBarButtonItem:sender 
               permittedArrowDirections:UIPopoverArrowDirectionAny 
                               animated:YES];    
}
-(IBAction) btnShowMovies:(id) sender {
    if (self.popoverController == nil) {
        MoviesViewController *movies = 
            [[MoviesViewController alloc] 
                initWithNibName:@"MoviesViewController" 
                         bundle:[NSBundle mainBundle]]; 
        UIPopoverController *popover = 
            [[UIPopoverController alloc] initWithContentViewController:movies]; 
        popover.delegate = self;
        [movies release];
//THIS IS THE LINE THAT YOU HAVE TO ADD
         popover.popoverBackgroundViewClass=[CustomPopoverBackgroundView class];
        self.popoverController = popover;
        [popover release];
    }
    CGRect popoverRect = [self.view convertRect:[btn frame] 
                                       fromView:[btn superview]];
    popoverRect.size.width = MIN(popoverRect.size.width, 100); 
    [self.popoverController 
        presentPopoverFromRect:popoverRect 
                        inView:self.view 
      permittedArrowDirections:UIPopoverArrowDirectionAny 
                      animated:YES];
}
Alright!!! Thats all! If someOne needs help just let me know. Best wishes!
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