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navigationBar变为纯透明
//第一种方法
//导航栏纯透明
[self.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
//去掉导航栏底部的黑线
self.navigationBar.shadowImage = [UIImage new];
//第二种方法
[[self.navigationBar subviews] objectAtIndex:0].alpha = 0;
tabBar同理
[self.tabBar setBackgroundImage:[UIImage new]];
self.tabBar.shadowImage = [UIImage new];
navigationBar根据滑动距离的渐变色实现
//第一种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGFloat offsetToShow = 200.0;//滑动多少就完全显示
CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;
[[self.navigationController.navigationBar subviews] objectAtIndex:0].alpha = alpha;
}
//第二种
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGFloat offsetToShow = 200.0;
CGFloat alpha = 1 - (offsetToShow - scrollView.contentOffset.y) / offsetToShow;
[self.navigationController.navigationBar setShadowImage:[UIImage new]];
[self.navigationController.navigationBar setBackgroundImage:[self imageWithColor:[[UIColor orangeColor]colorWithAlphaComponent:alpha]] forBarMetrics:UIBarMetricsDefault];
}
//生成一张纯色的图片
- (UIImage *)imageWithColor:(UIColor *)color
{
CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return theImage;
}
iOS navigationBar和tabBar变透明 & navigationBar根据滑动距离的渐变色实现
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原文地址：http://www.cnblogs.com/tongyuling/p/5822342.html
