README_EN.md

HBDNavigationBar

A custom UINavigationBar for smooth switching between various states, including bar style, bar tint color, background image, background alpha, bar hidden, title text attributes, tint color, shadow hidden...

Screenshots

ShadowImage transition between present and absent

NavigationBar transition between present and absent

It's diffrent from by calling setNavigationBarHidden:animated:

NavigationBar background alpha transition

NavigationBar transition between diffrent background

Usage

These effects are the result of three classes working together:

HBDNavigationBar inherits UINavigationBar

HBDNavigationController inherits UINavigationController and internally uses HBDNavigationBar

UIViewController(HBD) is a category with some configurable properties

@property (nonatomic, assign) UIBarStyle hbd_barStyle;   // The NavigationBar style, which determines the color of the status bar
@property (nonatomic, strong) UIColor *hbd_barTintColor; // NavigationBar background color
@property (nonatomic, strong) UIImage *hbd_barImage;     // NavigationBar background image
@property (nonatomic, strong) UIColor *hbd_tintColor;    // NavigationBar button color
@property (nonatomic, strong) NSDictionary *hbd_titleTextAttributes; // NavigationBar title attributes
@property (nonatomic, assign) float hbd_barAlpha;        // NavigationBar background alpha
@property (nonatomic, assign) BOOL hbd_barHidden;        // Whether to hide the NavigationBar
@property (nonatomic, assign) BOOL hbd_barShadowHidden;  // Whether to hide the shadowImage of the NavigationBar
@property (nonatomic, assign) BOOL hbd_backInteractive;  // Whether the UIViewController can responds to edge gesture, and can pop by click the back button of `UINavigationBar`. The default value is `YES`
@property (nonatomic, assign) BOOL hbd_swipeBackEnabled; // Whether the UIViewController can responds to edge gesture, the default value is `YES`

Actually simple to use:

Custom your NavigationBar style globally, just as using normal UINavigationBar.

// AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    [[UINavigationBar appearance] setTintColor:UIColor.blackColor];
    // ...

    return YES;
}

Use HBDNavigationController instead of UINavigationController.

DemoViewController *vc = [[DemoViewController alloc] init];
self.window.rootViewController = [[HBDNavigationController alloc] initWithRootViewController:vc];

If a UIViewController's NavigationBar style is different from global, tweak the style at its viewDidLoad using the properties in UIViewController(HBD). It's declarative API, you only need to set the unique features of that UIViewController, no need to clean up.

@implementation DemoViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    // hide the NavigationBar just for this UIViewController
    self.hbd_barHidden = YES;
}
@end

Don't forget to set HBDNavigationBar in addition to setting HBDNavigationController, if you use storyboard.

Caveat and Limitation

hbd_barHidden

hbd_barHidden doesn't really hide the NavigationBar, just make it transparent. Of course, the touch event can be pass through. Just because we don't really hide the NavigationBar, we can switch between the NavigationBar style smoothly and gracefully.

Background algorithm

hbd_barTintColor will be invalidated once the background image is set via hbd_barImage.

The calculation rules for the background are as follows:

1. Whether hbd_barImage has a value, if it is, set it to background, otherwise the next step
2. Whether hbd_barTintColor has a value, if it is, set it to background, otherwise the next step
3. Whether [[UINavigationBar appearance] backgroundImageForBarMetrics:UIBarMetricsDefault] has a value, if it is, set it to background, otherwise the next step
4. Whether [UINavigationBar appearance].barTintColor has a value, if it is, set it to background, otherwise the next step
5. Calculate the default background color based on NavigationBar#barStyle and set it to background

If you use an image to set the background and want transparency, use an image with transparency.

If blur effect is required, the color set to hbd_barTintColor should have non-zero alpha component. Don't use hbd_barAlpha to adjust the blur effect, it is used to control the alpha of the NavigationBar background, dynamically.

The image background is without blur effect.

Aways translucent

The value of the NavigationBar property translucent is always YES. You can not change it. It means that the UIViewController's view is always under the NavigationBar, which may bothering some guy. Our current solution to this problem is to define a base class:

@interface HBDViewController : UIViewController

@property (nonatomic, assign) BOOL hbd_extendedLayoutIncludesTopBar;

@end

BOOL hasAlpha(UIColor *color) {
    if (!color) {
        return YES;
    }
    CGFloat red = 0;
    CGFloat green= 0;
    CGFloat blue = 0;
    CGFloat alpha = 0;
    [color getRed:&red green:&green blue:&blue alpha:&alpha];
    return alpha < 1.0;
}

@implementation HBDViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    if (!(self.hbd_extendedLayoutIncludesTopBar || hasAlpha(self.hbd_barTintColor))) {
        self.edgesForExtendedLayout = UIRectEdgeNone;
    }
}

@end

The basic principle is that if the background has alpha, then the UIViewController's view should be under the NavigationBar, otherwise it will be below the NavigationBar. If our NavigationBar is opaque at first, but it may be transparent due to user actions, set the value of hbd_extendedLayoutIncludesTopBar to YES, remember to set it before [super viewDidLoad].

Intercept back event

Sometimes, we need to intercept the back click event and back gesture. For that, you can override the following method to return NO:

- (BOOL)hbd_backInteractive {
    // show alert
    return NO;
}

About hiding statusBar

If you need to hide the status bar, use this lib with HBDStatusBar

Requirements

iOS 8+

Installation

HBDNavigationBar is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'HBDNavigationBar', '~> 1.5.0'

License

HBDNavigationBar is available under the MIT license. See the LICENSE file for more info.