iOS改变Navigationbar透明度

iOS改变Navigationbar的透明度

- (void)setNavigationBarAlpha:(CGFloat)alpha {    UINavigationBar *navigationBar = self.navigationController.navigationBar;    UIView *bgView = [navigationBar valueForKey:@"_backgroundView"];    bgView.alpha = alpha;}

配合- (void)scrollViewDidScroll:(UIScrollView *)scrollView 函数的scrollView.contentOffset.y设置进行渐变。

demo地址 https://github.com/CodeY2J/NavigationBarAlpha