ios导航栏加上阴影

- (void)viewDidLoad

{

    [superviewDidLoad];

// Do any additional setup after loading the view.

    if ([self.navigationBarrespondsToSelector:@selector(setBackgroundImage:forBarMetrics:)]){

        [[UINavigationBarappearance] setBackgroundImage:[UIImageimageNamed:@"head"]forBarMetrics:UIBarMetricsDefault];

        self.navigationBar.layer.masksToBounds =NO;

        //设置阴影的高度

        self.navigationBar.layer.shadowOffset =CGSizeMake(0,3);

        //设置透明度

        self.navigationBar.layer.shadowOpacity =0.6;

        self.navigationBar.layer.shadowPath = [UIBezierPathbezierPathWithRect:self.navigationBar.bounds].CGPath;

    }

//    self.navigationBar.tintColor=MainHeaderColor;

}