仿iOS微信导航栏

iOS项目开发中，难免被iOS导航栏折腾，比较折腾的地方在:

自定义返回图标、隐藏返回按钮的文字
纯色导航栏与系统导航栏的平滑切换（比如微信的收付款页面）
系统导航栏与隐藏导航栏的平滑切换（比如微信朋友圈）
一些特立独行的PM或UI想要扩大导航栏的高度，比如50pt（系统默认是 44pt）
全屏返回手势
等等…

而且产品经常会飘来一句话：“咦，微信的导航栏怎么这么平滑”

常见自定义导航栏

设置背景透明

navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)

隐藏导航栏底部黑线

navigationController?.navigationBar.shadowImage = UIImage()

自定义返回按钮图标

navigationController?.navigationBar.backIndicatorImage = UIImage(named: "icons_outlined_back")
navigationController?.navigationBar.backIndicatorTransitionMaskImage = UIImage(named: "icons_outlined_back")

准备工具

某某助手上下载微信.ipa
class-dump
hopper disassembler
[可选]一台越狱设备

导出头文件

$ class-dump WeChat.app -H -o headers

找到我们感兴趣的几个头文件

MMUINavigationBar.h
FakeNavigationBar.h
MMUINavigationController.h
MMUIViewController.h

此时大概的猜测是：微信使用的是系统导航栏，然后在页面中进行了特殊处理以上遇到的问题

MMUINavigationBar

查看 MMUINavigationBar 头文件，发现MMUINavigationBar 是继承自 UINavigationBar的自定义导航栏，并且暴露出来的方法也比较少，猜测微信仅仅是修改了系统导航栏的某些属性。

@interface MMUINavigationBar : UINavigationBar
{
    UIView *_effectSubview;
}

@property(retain, nonatomic) UIView *effectSubview; // @synthesize effectSubview=_effectSubview;
- (id)hitTest:(struct CGPoint)arg1 withEvent:(id)arg2;
- (void)setAlpha:(double)arg1;
- (void)setBarStyle:(long long)arg1;
- (void)setTranslucent:(_Bool)arg1;
- (id)findBlurEffectView:(id)arg1;
- (id)findHiddenView:(id)arg1;
- (void)adjustShadowView;
- (void)layoutSubviews;
@end

FakeNavigationBar

FakeNavigationBar 是继承自 MMUINavigationBar，提供了一个可以添加subView的方法。从名字上看是“假”的导航栏，那么微信有可能是用假的导航栏盖在真的导航栏上面，能想到的场景是朋友圈滑动时，导航栏从全透明切换到系统导航栏。

@interface FakeNavigationBar : MMUINavigationBar
{
}
- (void)layoutSubviews;
- (void)didAddSubview:(id)arg1;
@end

MMUINavigationController

微信所有的NavigationController都使用的继承自 UINavigationController的MMUINavigationController

@interface MMUINavigationController : UINavigationController <UINavigationControllerDelegate>
{
    UIViewController *_popingViewController;
}

- (id)navigationController:(id)arg1 interactionControllerForAnimationController:(id)arg2;
- (id)navigationController:(id)arg1 animationControllerForOperation:(long long)arg2 fromViewController:(id)arg3 toViewController:(id)arg4;
- (void)layoutViewsForTaskBar;
- (void)viewWillLayoutSubviews;
- (void)viewDidLoad;
- (void)viewWillAppear:(_Bool)arg1;
- (void)setNavigationBarHidden:(_Bool)arg1 animated:(_Bool)arg2;
- (id)popViewControllerAnimated:(_Bool)arg1;
- (id)DispatchPopViewControllerAnimated:(_Bool)arg1;
- (id)initWithRootViewController:(id)arg1;
- (id)init;

@end

从头文件中可以看到，MMUINavigationController重写了UINavigationController的一些生命周期方法，在里面处理一些相关的逻辑。

MMUIViewController

MMUIViewController 是微信中所有ViewController的基类。由于头文件代码较多，我仅将与导航栏相关的代码保留，其余都删掉了。

@interface MMUIViewController : UIViewController <IUiUtilExt, MMUIViewControllerDelegate, UIGestureRecognizerDelegate>
{
    unsigned int m_uiVcType;
    UINavigationController *m_navigationController;
    MMTitleView *m_baseTitleView;
    MMDelegateProxy<UIGestureRecognizerDelegate> *m_interactivePopGestureRecognizerDelegate;
    UIBarButtonItem *m_leftBarBtnItem;
    UIBarButtonItem *m_rightBarBtnItem;
    UIColor *m_titleColor;
    MMUINavigationBar *fakeNaviView;
    UIView *m_navHeaderView;
    UIView *m_navSepLine;
    NSString *m_navTitle;
    NSString *m_navSubTitle;
    _Bool m_navLoading;
    UIView *m_navRightView;
    double m_navTitleOffset;
    _Bool m_navCustomView;
    MMNavBarInteractiveConfig *_navBarInteractiveConfig;
}

@property(retain, nonatomic) UIPanGestureRecognizer *scrollViewInteractivePanGesture; // @synthesize scrollViewInteractivePanGesture=_scrollViewInteractivePanGesture;
@property(retain, nonatomic) MMNavBarInteractiveConfig *navBarInteractiveConfig; // @synthesize navBarInteractiveConfig=_navBarInteractiveConfig;
@property(nonatomic) unsigned int m_uiVcType; // @synthesize m_uiVcType;

- (id)mmNavigationController:(id)arg1 interactionControllerForAnimationController:(id)arg2;
- (id)mmNavigationController:(id)arg1 animationControllerForOperation:(long long)arg2 fromViewController:(id)arg3 toViewController:(id)arg4;
- (_Bool)gestureRecognizerShouldBegin:(id)arg1;
- (_Bool)interactivePopGestureRecognizerShouldBegin:(id)arg1;
- (void)onNavigationBarHiddenChanged;
- (void)onNavigationBarAlphaChanged;
- (void)removeFakeNaviView;
- (void)restoreNavigationBar;
- (void)internalAddFakeNaviView:(id)arg1;
- (void)addFakeNaviView;
- (_Bool)useCustomNavibar;
- (void)restoreNavHeaderIfNeed;
- (id)getNavBarSepLine;
- (void)initNavibarSepLine;
- (void)initNavHeaderIfNeed;
- (_Bool)useWhiteForegroundColor;
- (id)navigationTitleColor;
- (void)onNavigationBarBackgroundColorChange;
- (_Bool)showNavigationBarSepLine;
- (_Bool)navigationBarBlurEffect;
- (id)navigationBarBackgroundColor;
- (_Bool)useTransparentNavibar;
- (void)updateStatusBarColor;
- (_Bool)useBlackStatusbar;
- (_Bool)hidesStatusBar;
- (void)protectStatusBarFromBeingFuckedByForeGround:(SEL)arg1;
- (void)setStatusBarFontBlack;
- (void)setStatusBarFontWhite;
- (void)setStatusBarHidden:(_Bool)arg1 withAnimation:(long long)arg2;
- (void)setStatusBarHidden:(_Bool)arg1;
- (void)setTopBarsHidden:(_Bool)arg1 animated:(_Bool)arg2;
- (void)changeTopBarsHiddenAnimated:(_Bool)arg1;
- (void)setTitleOnly:(id)arg1;
- (void)setTitleInterfaceOritation:(long long)arg1;
- (void)reloadTitleView;
- (double)adjustedStatusBarHeight;
- (_Bool)hasTitle;
- (void)setTitleView:(id)arg1;
- (void)setTitleColor:(id)arg1;
- (void)restoreNavigationBarBkg;
- (void)removeNavigationBarBkg;
- (double)getContentViewYforTranslucentNaviBar;
- (void)updateNavibarSepline;
- (void)adjustViewAndNavBarRect;
- (id)titleView;
- (double)navigationBarHeight;
- (double)statusBarHeight;
- (void)setNavigationBarAlpha:(double)arg1 withTitleIncluded:(_Bool)arg2;
- (void)setNavigationBarY:(double)arg1;
- (void)restoreNavigationBarToFullSize;
- (void)restoreNavigationBarToFullSizeAnimatedWithDuration:(double)arg1;
- (void)restoreNavigationBarToFullSizeOnScrollToTop;
- (void)updateFadeBkgAlpha;
- (void)viewDidLayoutSubviewsInNavBar;
- (void)viewWillDisappearInNavBar:(_Bool)arg1;
- (void)viewWillAppearInNavBar:(_Bool)arg1;

@end

MMUIViewController中有很多对导航栏处理的方法和属性。

WXNavigationBar

仿照微信的实现方式，做了一个仿微信导航栏的类库，无需任何配置，直接使用即可。

支持设置导航栏背景颜色
支持设置导航栏背景图片
支持Large Title模式
支持iOS 13 暗黑模式
支持全屏手势返回

实现原理

WXNavigationBar通过将系统导航栏设为透明，在View中添加一个NavigationBar相同大小，相同位置的View作为假的导航栏。

原始的UINavigationBar还是用于处理手势相关逻辑，WXNavigationBar用于展示部分，比如背景颜色、背景图片等。

所以你可以像平常使用UINavigationBar一样，当你需要处理导航栏显示的时候，使用WXNavigationBar

使用方式

使用WXNavigationBar不需要特殊的初始化配置，默认的就如同微信中的导航栏一样。当你需要配置时，有两种方式可以配置。

使用UINavigationController.Nav中的属性对UINavigationController进行配置，或者重写UIViewController中的相关属性对UIViewController进行配置。

具体的用法可以参考 WXNavigationBar