iOS开发之设置navigationBar的背景颜色为无色

<span style="color:#FF0000;">//在页面消失的时候就让navigationbar还原样式</span>
-(void)viewWillDisappear:(BOOL)animated{
    [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"Top_Article.png"] forBarMetrics:UIBarMetricsDefault];
    [self.navigationController.navigationBar setShadowImage:nil];
    self.navigationController.navigationBar.translucent = NO;
}
<span style="color:#FF0000;"> //在页面将要出现的时候,就让navigationbar的背景颜色设置为nil</span>
- (void)viewDidAppear:(BOOL)animated {
    [self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
    [self.navigationController.navigationBar setShadowImage:[UIImage new]];
    self.navigationController.navigationBar.translucent = YES;
}

设置成这样之后,我们把tableView的contentInset设置成这样

self.tableView.contentInset = UIEdgeInsetsMake(-64, 0, 0, 0);

然后整个tableView就可以在页面中置顶显示了