iOS导航栏透明效果设置

先看下效果图：并没有做滚动显示导航栏，下次补上！

效果图.gif

相关代码如下：

先设置一个自定义背景图片
@property (nonatomic ,strong) UIImageView * imageViewBar;

-(void)viewDidLoad{
      其他配置
     [self setNaVationBar];
}
- (void)setNaVationBar {
    // 透明状态栏的延伸
      self.edgesForExtendedLayout = UIRectEdgeNone;
    //可有可无
     [self.navigationController.navigationBar setBackgroundImage:nil
                                             forBarPosition:UIBarPositionAny
                                                 barMetrics:UIBarMetricsDefault];
    //一条线   
    self.navigationController.navigationBar.shadowImage = [UIImage new];
}

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    //设置状态栏背景字体颜色
   //(图片设置会导致全局白字,下面这句可以在个别界面设置成黑字)
    [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleDefault;

    //导航栏透明设置
    self.imageViewBar = self.navigationController.navigationBar.subviews.firstObject;
    self.imageViewBar.alpha = 0;
}

- (void)viewWillDisappear:(BOOL)animated {
     //恢复白色
     [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent;
      //恢复不透明
    self.imageViewBar.alpha = 1;

}