使用过程中有卡顿和测试失效的问题，还需要继续研究优化下
上一篇相关文章：iOS侧滑pop返回的第三方整理研究
知识点：
Runtime+分类+property现实属性
前言
当在实际开发中遇到使用系统navigationBar隐藏或显示展示某些页面，总共有以下4种可能：
显示导航栏页面A->显示导航栏页面B
显示导航栏页面A->隐藏导航栏页面B
隐藏导航栏页面A->显示导航栏页面B
隐藏导航栏页面A->隐藏导航栏页面B
在实际开发中，经常很难同时处理好这几种可能，经常会出现导航栏突然闪一下或是进入页面后才隐藏导航栏，有些在侧滑时会导航栏位置是空的或是黑的，显得特别怪异，但FDFullscreenPopGesture却很好的处理了这个难题，现在研究下这个库的实现
用法
在使用FDFullscreenPopGesture这个库时，在需要隐藏系统导航栏的页面的viewDidLoad方法里设置下fd_prefersNavigationBarHidden属性，需要显示导航栏的页面什么都不处理，使用起来非常简单，如下
// 引入处理侧滑pop返回及处理有无navbar的库
#import "UINavigationController+FDFullscreenPopGesture.h"
@interface HomeController ()
@end
@implementation HomeController
#pragma mark - life cycle
- (void)viewDidLoad {
[super viewDidLoad];
self.fd_prefersNavigationBarHidden = YES;
}
@end
原理研究
1、在UINavigationController+FDFullscreenPopGesture文件里写了一个UIViewController的分类UINavigationController+FDFullscreenPopGesture,并利用property和Runtime的方式给UIViewController添加fd_prefersNavigationBarHidden属性
@interface UIViewController (FDFullscreenPopGesture)
@property (nonatomic, assign) BOOL fd_prefersNavigationBarHidden;
@end
@implementation UIViewController (FDFullscreenPopGesture)
- (BOOL)fd_prefersNavigationBarHidden
{
return [objc_getAssociatedObject(self, _cmd) boolValue];
}
- (void)setFd_prefersNavigationBarHidden:(BOOL)hidden
{
objc_setAssociatedObject(self, @selector(fd_prefersNavigationBarHidden), @(hidden), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end
2、对UINavigationController添加一个分类UINavigationController (FDFullscreenPopGesture)，使用Runtime的swizzle黑魔法将pushViewController:animated:的实现替换，增加上额外的处理fd_pushViewController:animated:
,在这个增加额外的方法里的主要功能是
- 2.1、给UINavigationController的
interactivePopGestureRecognizer.view添加一个新的手势，这个添加的手势代理是写的另一个类，同时让系统默认的处理侧滑pop返回的手势注册者失效，目的是让重写了navigationItem的backItem后也能响应侧滑返回
if (![self.interactivePopGestureRecognizer.view.gestureRecognizers containsObject:self.fd_fullscreenPopGestureRecognizer]) {
// Add our own gesture recognizer to where the onboard screen edge pan gesture recognizer is attached to.
[self.interactivePopGestureRecognizer.view addGestureRecognizer:self.fd_fullscreenPopGestureRecognizer];
// Forward the gesture events to the private handler of the onboard gesture recognizer.
NSArray *internalTargets = [self.interactivePopGestureRecognizer valueForKey:@"targets"];
id internalTarget = [internalTargets.firstObject valueForKey:@"target"];
SEL internalAction = NSSelectorFromString(@"handleNavigationTransition:");
self.fd_fullscreenPopGestureRecognizer.delegate = self.fd_popGestureRecognizerDelegate;
[self.fd_fullscreenPopGestureRecognizer addTarget:internalTarget action:internalAction];
// Disable the onboard gesture recognizer.
self.interactivePopGestureRecognizer.enabled = NO;
}
- 2.2、设置当前即将要push的ViewController的当要处理隐藏导航栏时的block,这个方法的逻辑是在push时给设置一个block,如下
__weak typeof(self) weakSelf = self;
_FDViewControllerWillAppearInjectBlock block = ^(UIViewController *viewController, BOOL animated) {
__strong typeof(weakSelf) strongSelf = weakSelf;
if (strongSelf) {
[strongSelf setNavigationBarHidden:viewController.fd_prefersNavigationBarHidden animated:animated];
}
};
appearingViewController.fd_willAppearInjectBlock = block;
这个block会在viewWillAppear:animated:这个hook的方法里回调，而这个block的逻辑是根据fd_prefersNavigationBarHidden来动态隐藏或显示UINavigationBar，同时节将被隐藏的UIViewController如果没有设置这个block，也会将同样的逻辑设置给这个Controller，保证在UINavigationController的栈里管理的所有UIViewController都有这个block，全部代码如下：
- (void)fd_setupViewControllerBasedNavigationBarAppearanceIfNeeded:(UIViewController *)appearingViewController
{
if (!self.fd_viewControllerBasedNavigationBarAppearanceEnabled) {
return;
}
__weak typeof(self) weakSelf = self;
_FDViewControllerWillAppearInjectBlock block = ^(UIViewController *viewController, BOOL animated) {
__strong typeof(weakSelf) strongSelf = weakSelf;
if (strongSelf) {
[strongSelf setNavigationBarHidden:viewController.fd_prefersNavigationBarHidden animated:animated];
}
};
// Setup will appear inject block to appearing view controller.
// Setup disappearing view controller as well, because not every view controller is added into
// stack by pushing, maybe by "-setViewControllers:".
appearingViewController.fd_willAppearInjectBlock = block;
UIViewController *disappearingViewController = self.viewControllers.lastObject;
if (disappearingViewController && !disappearingViewController.fd_willAppearInjectBlock) {
disappearingViewController.fd_willAppearInjectBlock = block;
}
}
- 2.3、在UIViewController即将push出新的Controller，当前Controller解决不可见时也会执行一段代码,代码逻辑为如果解决要push出来的代码如果不隐藏导航栏，则设置
[self.navigationController setNavigationBarHidden:NO animated:NO]
全部代码如下：
- (void)fd_viewWillDisappear:(BOOL)animated
{
// Forward to primary implementation.
[self fd_viewWillDisappear:animated];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
UIViewController *viewController = self.navigationController.viewControllers.lastObject;
if (viewController && !viewController.fd_prefersNavigationBarHidden) {
[self.navigationController setNavigationBarHidden:NO animated:NO];
}
});
}
总结
对代码进行了深入的初步研究后发现，原理是让每个Controller的
viewWillAppear:animated:方法里都执行了一遍是否隐藏导航栏的代码逻辑，比如我在BaseViewController里定义了一个lh_hideNavBar熟悉，只要这样调用就会OK,只是FDFullscreenPopGesture使用了分类的方式，另外也添加了更多判断逻辑的代码，我的代码如下
GitHub：TestPopGestureSolution7
吸收了同事的写法、TZScrollViewPopGesture、FDFullscreenPopGesture后写了一个比较简单的封装整理，全部代码如下（总共112行，包含侧滑、隐藏navbar、UIScrollView侧滑）：
UIViewController+LHNavigationGesture.h
#import <UIKit/UIKit.h>
@interface UIViewController (LHNavigationGesture) <UIGestureRecognizerDelegate>
/// 是否隐藏导航栏
@property (nonatomic,assign) BOOL lh_hideNavBar;
/// 给view添加侧滑返回效果
- (void)lh_addPopGestureToView:(UIView *)view;
@end
UIViewController+LHNavigationGesture.m
#import "UIViewController+LHNavigationGesture.h"
#import <objc/runtime.h>
@implementation UIViewController (LHNavigationGesture)
+ (void)load
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
[self swizzleBarHidden];
[self swizzlePopGesture];
});
}
#pragma mark - ******** 支持手势pop侧滑
+ (void)swizzlePopGesture
{
Method viewDidLoad_originalMethod = class_getInstanceMethod(self, @selector(viewDidLoad));
Method viewDidLoad_swizzledMethod = class_getInstanceMethod(self, @selector(lh_viewDidLoad));
method_exchangeImplementations(viewDidLoad_originalMethod, viewDidLoad_swizzledMethod);
}
- (void)lh_viewDidLoad
{
[self lh_viewDidLoad];
self.navigationController.interactivePopGestureRecognizer.delegate = (id)self;
}
#pragma mark - ******** 支持navigationBar的隐藏现实不突兀
+ (void)swizzleBarHidden
{
Method viewWillAppear_originalMethod = class_getInstanceMethod(self, @selector(viewWillAppear:));
Method viewWillAppear_swizzledMethod = class_getInstanceMethod(self, @selector(lh_viewWillAppear:));
method_exchangeImplementations(viewWillAppear_originalMethod, viewWillAppear_swizzledMethod);
}
- (void)lh_viewWillAppear:(BOOL)animated
{
[self lh_viewWillAppear:animated];
[self.navigationController setNavigationBarHidden:self.lh_hideNavBar animated:animated];
}
- (void)setLh_hideNavBar:(BOOL)lh_hideNavBar
{
objc_setAssociatedObject(self, @selector(lh_hideNavBar), @(lh_hideNavBar), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (BOOL)lh_hideNavBar
{
return [objc_getAssociatedObject(self, _cmd) boolValue];
}
#pragma mark - ******** 支持UIScrollView侧滑滚动
- (void)lh_addPopGestureToView:(UIView *)view {
if (!view) return;
if (!self.navigationController) {
// 在控制器转场的时候，self.navigationController可能是nil,这里用GCD和递归来处理这种情况
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.05 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[self lh_addPopGestureToView:view];
});
} else {
UIPanGestureRecognizer *pan = self.lh_popGestureRecognizer;
if (![view.gestureRecognizers containsObject:pan]) {
[view addGestureRecognizer:pan];
}
}
}
- (UIPanGestureRecognizer *)lh_popGestureRecognizer {
UIPanGestureRecognizer *pan = objc_getAssociatedObject(self, _cmd);
if (!pan) {
NSArray *internalTargets = [self.navigationController.interactivePopGestureRecognizer valueForKey:@"targets"];
id target = [internalTargets.firstObject valueForKey:@"target"];
SEL action = NSSelectorFromString(@"handleNavigationTransition:");
pan = [[UIPanGestureRecognizer alloc] initWithTarget:target action:action];
pan.maximumNumberOfTouches = 1;
pan.delegate = self.navigationController;
self.navigationController.interactivePopGestureRecognizer.enabled = NO;
objc_setAssociatedObject(self, _cmd, pan, OBJC_ASSOCIATION_ASSIGN);
}
return pan;
}
@end
#pragma mark ******** 支持UIScrollView类型侧滑滚动
@interface UINavigationController (LHPopGesturePrivate)
@end
@implementation UINavigationController (LHPopGesture)
- (BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer {
if ([[self valueForKey:@"_isTransitioning"] boolValue]) {
return NO;
}
if ([self.navigationController.transitionCoordinator isAnimated]) {
return NO;
}
if (self.childViewControllers.count <= 1) {
return NO;
}
// 侧滑手势触发位置
CGPoint location = [gestureRecognizer locationInView:self.view];
CGPoint offSet = [gestureRecognizer translationInView:gestureRecognizer.view];
BOOL ret = (0 < offSet.x && location.x <= 40);
return ret;
}
/// 只有当系统侧滑手势失败了，才去触发ScrollView的滑动
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
return YES;
}
@end
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