设置导航栏透明

self.navigationController.navigationBar.barTintColor = BACKGROUND_COLOR;//颜色

[[[self.navigationController.navigationBar subviews]objectAtIndex:0] setAlpha:0.1];//透明度

其次还有这个

    [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];

    [self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init] ];