c_cpp JTDropShadowFixNavigationViewController - 在UINavigationBar中使用自定义阴影（针对iOS 6.1修复）

Posted 2021-05-14

# Using custom drop shadows in UINavigationBar (fix for iOS 6.1)

This is an update to the [Adding Drop Shadow on UINavigationBar](http://ioscodesnippet.com/post/10437516225/adding-drop-shadow-on-uinavigationbar) which was written prior to iOS 6.0

Since iOS 6.0 Apple introduced the `-[UINavigationBar shadowImage]` property. We should probably leverage that, which are also UIAppearance selectors.

    // Configure your images
    UIImage *background = [UIImage imageNamed:@"titlebar44"];
    UIImage *shadow = [UIImage imageNamed:@"titlebar-bottom-highlight"];

    // Using the appearance proxy
    // Note: setBackgroundImage:forBarMetrics has been documented to be
    // **compulsory** to enable the displaying of the custom shadow image.
    [[UINavigationBar appearance] setBackgroundImage:background forBarMetrics:UIBarMetricsDefault];
    [[UINavigationBar appearance] setShadowImage:shadow];


You probably went with similar code, but the custom shadow just didn't show up, right?

The problem occurs because of the implementation on UINavigationBar, the clipsToBounds property is needed to be set to NO, and this step has been missing from the documentation. (At least I didn't find it)

Most probably you'll need to set self.navigationController.navigationBar.clipsToBounds = NO in every UIViewController subclass you wrote, a more convenience way is to subclass UINavigationController and have it do the job for you. And I've created a snippet for you.

<script src="https://gist.github.com/6591926.js?file=JTDropShadowFixNavigationViewController.h"> </script>
<script src="https://gist.github.com/6591926.js?file=JTDropShadowFixNavigationViewController.m"> </script>

So now you can initialise your view controllers in code like this:

    UIViewController *controller; // configure your view controller
    UINavigationController *navController = [[JTDropShadowFixNavigationViewController alloc] initWithRootViewController:controller];
  
Or if you use storyboard, simply change the subclass of your UINavigationController to JTDropShadowFixNavigationViewController.

![](https://gist.github.com/jamztang/6591926/raw/0437477ed7efd34a81bcc66a47de30c95071d7cb/modify-class.png)

**In fact there's an even simpler method you'll notice in the snippet.**

This is a hack that adds a category method to always set clipsToBounds to NO for UINavigationBar. Enable it defining this constant somewhere in your code (recommended in .pch):

    #define ENABLE_JTDROPSHADOW_GLOBAL_FIX 1

Let me know your thoughts!

Jamz

Copyright (c) 2013 Jamz Tang <[e-mail]>
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is furnished
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The above copyright notice and this permission notice shall be included in all
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THE SOFTWARE.

/*
 * This file is part of the http://ioscodesnippet.com
 * (c) Jamz Tang <[e-mail]>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */


#import "JTDropShadowFixNavigationViewController.h"

@implementation JTDropShadowFixNavigationViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationBar.clipsToBounds = NO;
}

@end

#if ENABLE_JTDROPSHADOW_GLOBAL_FIX

@interface UINavigationBar (JTDropShadowFix)

@end

@implementation UINavigationBar (JTDropShadowFix)

- (void)awakeFromNib {
    self.clipsToBounds = NO;
}

@end

#endif

/*
 * This file is part of the http://ioscodesnippet.com
 * (c) Jamz Tang <[e-mail]>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

#import <UIKit/UIKit.h>

@interface JTDropShadowFixNavigationViewController : UINavigationController

@end