写在前面
导航栏是我们开发中经常遇见的一个控件,我们大概都明白它的工作机制等等,以前用的是同事之前封装好的一个基类,基本上自己也不用对它进行太多的修改,这也是给自己埋下了隐患,最近在做的工作是接手的别人写的代码,在对工程代码进行熟悉和开发的过程中,针对导航控制器遇到的一些问题做一下总结。
主要问题
在开发过程中主要发现了两个问题,接下来就逐一记录一下解决的方法
一、手势右滑返回效果失效
在我们经常使用的APP中,已经习惯右滑返回这个效果,可是我发现我们的APP中这个功能失效了,只能点击左上角的返回按钮才能执行返回这个效果。后来查了一下发现,导致这个问题的原因是因为我们自己自定义了左上角的leftBarButtonItem,我们自定义了这个BarButtonItem使得系统不能捕获pop手势了。
解决方法:
创建一个UINavigationController的子类LGJBaseNavController,该类@interface LGJBaseNavController ()
1 设置手势的delegate为self,导航控制器的delegate也为self。
- (void)viewDidLoad { [super viewDidLoad]; __weak LGJBaseNavController *weakSelf = self; if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) { self.interactivePopGestureRecognizer.delegate = weakSelf; self.delegate = weakSelf; } } - (UIViewController *)popViewControllerAnimated:(BOOL)animated { return [super popViewControllerAnimated:animated]; }
2 在转场/过渡的时候禁用 interactivePopGestureRecognizer当用户在转场的时候触发一个后退手势,这时候容易各种其他事件也会被唤醒,导航栈或边混乱。那么在转场效果的过程中禁用手势识别,当新的视图控制器加载完成后再启用。
#pragma mark - UINavigationControllerDelegate - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated { if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) { self.interactivePopGestureRecognizer.enabled = NO; } //设置返回按钮 if (self.viewControllers.count > 0) { viewController.navigationItem.leftBarButtonItem = [self backButtonItem]; } [super pushViewController:viewController animated:animated]; } - (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated { if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) { self.interactivePopGestureRecognizer.enabled = YES; } }
3 使navigationcontroller中第一个控制器不响应右滑pop手势
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer { if ([self.childViewControllers count] == 1) { return NO; } return YES; }
4 解决多个手势冲突 同时接受多个手势
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer { return YES; }
5 解决在手指滑动时候,被pop的viewController中的UIscrollView会跟着一起滚动
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer { return [gestureRecognizer isKindOfClass:UIScreenEdgePanGestureRecognizer.class]; }
关于这个处理复杂手势冲突的方法有几个类似的手势代理方法:
//手指触摸屏幕后回调的方法,返回NO则不再进行手势识别,方法触发等 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch; //开始进行手势识别时调用的方法,返回NO则结束,不再触发手势 - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer; //是否支持多时候触发,返回YES,则可以多个手势一起触发方法,返回NO则为互斥 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer; //下面这个两个方法也是用来控制手势的互斥执行的 //这个方法返回YES,第一个手势和第二个互斥时,第一个会失效 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0); //这个方法返回YES,第一个和第二个互斥时,第二个会失效 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);
可以将这几个方法写在一个UINavigationController的子类里面,然后在AppDelegate中设置self.window.rootViewController = [[LGJBaseNavController alloc] initWithRootViewController:vc1];可以处理全局的导航控制器关于这个右滑手势返回失效的问题,我以上写的这些方法直接写在里面就可以。另外说一句,在这个LGJBaseNavController中可以设置导航栏的一些自定义样式:比如这种样式就可以在LGJBaseNavController初始化中设置:
navBar.png
+ (void)initialize { //bar样式 UINavigationBar *bar = [UINavigationBar appearance]; [bar setBarStyle:UIBarStyleDefault]; [bar setBarTintColor:[UIColor blackColor]]; [bar setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor whiteColor], NSForegroundColorAttributeName, nil]]; //barButton样式 UIBarButtonItem *item = [UIBarButtonItem appearance]; //Normal NSMutableDictionary *textAtts = [NSMutableDictionary dictionary]; textAtts[NSForegroundColorAttributeName] = [UIColor orangeColor]; textAtts[NSFontAttributeName] = [UIFont systemFontOfSize:13]; [item setTitleTextAttributes:textAtts forState:UIControlStateNormal]; //不可用状态 NSMutableDictionary *disableTextAtts = [NSMutableDictionary dictionary]; disableTextAtts[NSForegroundColorAttributeName] = [UIColor colorWithRed:123/255.0 green:123/255.0 blue:123/255.0 alpha:1]; disableTextAtts[NSFontAttributeName] = [UIFont systemFontOfSize:13]; [item setTitleTextAttributes:disableTextAtts forState:UIControlStateDisabled]; }
二、隐藏NavigationBar返回时,上面会有空缺
这个应该也是我们经常见的效果,比如vc1跳转vc2,vc2的导航栏是隐藏的,当从vc2返回vc1时,在这个过程中,放慢看上面会有缺失一块,放快了看就是闪屏,这个效果对用户也是不友好的,这个解决方法比较简单。就是在次级viewControleller中在设置setNavigationBarHidden时这样设置: <重要的是后面的animated参数>
- (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; [self.navigationController setNavigationBarHidden:YES animated:animated]; } - (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; [self.navigationController setNavigationBarHidden:NO animated:animated]; }
总结
以上两个问题就是我最近遇到的问题,在网上查资料的时候发现真正有解决办法的好建议不太多,通篇一律都是同一片资料的copy,就算加点儿自己的见解也成啊,唉。。。记下来这两个常见问题,温故而知新