在最近一个项目中碰到这样一个场景,在被push进来的一个页面设置导航栏透明,且要求控制对tableview组的头视图进行悬停显示,nav随着tableview偏移量改变透明度,当然这样的需求确实不是什么难事,但是如果当前页面继续push一个不需要此类效果的页面,当在返回当前页面的时候就会出现一个坑,nav的展示很突兀,下面是直接上解决方法...ps:假设A页面为需要设置透明,B页面被Apush且不需要设置透明

首先在需要设置导航栏透明的页面的viewDidload中写上

? 1 2 3 4 5 6 7 8 9 self.title = @"Title"; [self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault]; self.navigationController.navigationBar.shadowImage = [UIImage new]; self.barImageView = self.navigationController.navigationBar.subviews.firstObject; self.barImageView.alpha = 0; //设置状态栏 [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent]; //设置标题颜色 self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor clearColor]};

在scrollViewDidScroll代理方法中

? 1 2 3 4 5 6 7 8 9 10 11 12 -(void)scrollViewDidScroll:(UIScrollView *)scrollView { CGFloat offset = scrollView.contentOffset.y; //根据自己需要设置(136)的大小 CGFloat alpha = offset / 136; _barImageView.alpha = alpha; //记录下当前的透明度,在返回当前页面时需要 _alpha = alpha; [[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithFloat:alpha] forKey:@"_alpha"]; //设置标题的透明度 self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor colorWithWhite:0 alpha:alpha]}; }

当前页的viewWillAppear, viewDidAppear, viewWillDisappear

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 -(void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; self.table.delegate = self; } -(void)viewDidAppear:(BOOL)animated { BOOL isGesturePop = [[[NSUserDefaults standardUserDefaults] objectForKey:@"isGesturePop"] boolValue]; if (!isGesturePop) { _barImageView.alpha = _alpha; self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor colorWithWhite:0 alpha:_alpha]}; } [super viewDidAppear:animated]; } -(void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; self.table.delegate = nil; self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor blackColor]}; _barImageView.alpha = 1; [[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithBool:NO] forKey:@"isGesturePop"]; }

那么在我们需要push的下一个页面需要什么操作呢,我们需要在这个页面显示正常的nav并且禁掉系统的手势pop,自己写一个pop手势,以方便我们拿到pop滑动时的偏移量,在做的时候使用了两个类,在最后会有源码贴出

B.m 须遵守UIGestureRecognizerDelegate,并导入NavigationInteractiveTransition.h

全局变量

? 1 @property (nonatomic, strong) NavigationInteractiveTransition *navT;

viewDidLoad

? 1 2 3 4 5 6 7 8 9 10 11 12 13 self.navigationController.interactivePopGestureRecognizer.enabled = NO; UIGestureRecognizer *gesture = self.navigationController.interactivePopGestureRecognizer; gesture.enabled = NO; UIView *gestureView = gesture.view; UIPanGestureRecognizer *popRecognizer = [[UIPanGestureRecognizer alloc] init]; popRecognizer.delegate = self; popRecognizer.maximumNumberOfTouches = 1; [gestureView addGestureRecognizer:popRecognizer]; _navT = [[NavigationInteractiveTransition alloc] initWithViewController:self.navigationController]; [popRecognizer addTarget:_navT action:@selector(handleControllerPop:)];

UIGestureRecognizerDelegate 代理方法gestureRecognizerShouldBegin

? 1 2 3 4 5 6 7 8 - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer { //记录当前是是否是通过手势滑动回去 [[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithBool:YES] forKey:@"isGesturePop"]; /** * 这里有两个条件不允许手势执行，1、当前控制器为根控制器；2、如果这个push、pop动画正在执行（私有属性） */ return self.navigationController.viewControllers.count != 1 && ![[self.navigationController valueForKey:@"_isTransitioning"] boolValue]; }

需要依赖的两个类源码

NavigationInteractiveTransition.h

? 1 2 3 4 5 6 7 8 #import <UIKit/UIKit.h> @class UIViewController, UIPercentDrivenInteractiveTransition; @interface NavigationInteractiveTransition : NSObject <UINavigationControllerDelegate> - (instancetype)initWithViewController:(UIViewController *)vc; - (void)handleControllerPop:(UIPanGestureRecognizer *)recognizer; - (UIPercentDrivenInteractiveTransition *)interactivePopTransition; @end

NavigationInteractiveTransition.m

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 #import "NavigationInteractiveTransition.h" #import "PopAnimation.h" @interface NavigationInteractiveTransition () @property (nonatomic, weak) UINavigationController *vc; @property (nonatomic, strong) UIPercentDrivenInteractiveTransition *interactivePopTransition; @property(nonatomic, strong) UIImageView *barImageView; @end @implementation NavigationInteractiveTransition - (instancetype)initWithViewController:(UIViewController *)vc { self = [super init]; if (self) { self.vc = (UINavigationController *)vc; self.vc.delegate = self; } return self; } /** * 我们把用户的每次Pan手势操作作为一次pop动画的执行 */ - (void)handleControllerPop:(UIPanGestureRecognizer *)recognizer { /** * interactivePopTransition就是我们说的方法2返回的对象，我们需要更新它的进度来控制Pop动画的流程，我们用手指在视图中的位置与视图宽度比例作为它的进度。 */ CGFloat progress = [recognizer translationInView:recognizer.view].x / recognizer.view.bounds.size.width; [self.vc.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault]; self.vc.navigationBar.shadowImage = [UIImage new]; self.barImageView = self.vc.navigationBar.subviews.firstObject; CGFloat alpha = [[[NSUserDefaults standardUserDefaults] objectForKey:@"_alpha"] floatValue]; self.barImageView.alpha = 1 - progress > alpha ? alpha : 1 - progress; // NSLog(@"===progress==%.2f",progress); /** * 稳定进度区间，让它在0.0（未完成）～1.0（已完成）之间 */ progress = MIN(1.0, MAX(0.0, progress)); if (recognizer.state == UIGestureRecognizerStateBegan) { /** * 手势开始，新建一个监控对象 */ self.interactivePopTransition = [[UIPercentDrivenInteractiveTransition alloc] init]; /** * 告诉控制器开始执行pop的动画 */ [self.vc popViewControllerAnimated:YES]; } else if (recognizer.state == UIGestureRecognizerStateChanged) { /** * 更新手势的完成进度 */ [self.interactivePopTransition updateInteractiveTransition:progress]; } else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) { /** * 手势结束时如果进度大于一半，那么就完成pop操作，否则重新来过。 */ if (progress > 0.5) { [self.interactivePopTransition finishInteractiveTransition]; self.barImageView.alpha = 0;; } else { [self.interactivePopTransition cancelInteractiveTransition]; } self.interactivePopTransition = nil; } } - (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC { /** * 方法1中判断如果当前执行的是Pop操作，就返回我们自定义的Pop动画对象。 */ if (operation == UINavigationControllerOperationPop) return [[PopAnimation alloc] init]; return nil; } - (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController { /** * 方法2会传给你当前的动画对象animationController，判断如果是我们自定义的Pop动画对象，那么就返回interactivePopTransition来监控动画完成度。 */ if ([animationController isKindOfClass:[PopAnimation class]]) return self.interactivePopTransition; return nil; } @end

PopAnimation.h

? 1 2 3 4 5 6 #import <Foundation/Foundation.h> #import <UIKit/UIKit.h> @interface PopAnimation : NSObject <UIViewControllerAnimatedTransitioning> @end

PopAnimation.m

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 #import "PopAnimation.h" @interface PopAnimation () @property (nonatomic, strong) id <UIViewControllerContextTransitioning> transitionContext; @end @implementation PopAnimation - (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext { //这个方法返回动画执行的时间 return 0.25; } /** * transitionContext你可以看作是一个工具，用来获取一系列动画执行相关的对象，并且通知系统动画是否完成等功能。 */ - (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext { /** * 获取动画来自的那个控制器 */ UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; /** * 获取转场到的那个控制器 */ UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; /** * 转场动画是两个控制器视图时间的动画，需要一个containerView来作为一个“舞台”，让动画执行。 */ UIView *containerView = [transitionContext containerView]; [containerView insertSubview:toViewController.view belowSubview:fromViewController.view]; NSTimeInterval duration = [self transitionDuration:transitionContext]; /** * 执行动画，我们让fromVC的视图移动到屏幕最右侧 */ [UIView animateWithDuration:duration animations:^{ fromViewController.view.transform = CGAffineTransformMakeTranslation([UIScreen mainScreen].bounds.size.width, 0); }completion:^(BOOL finished) { /** * 当你的动画执行完成，这个方法必须要调用，否则系统会认为你的其余任何操作都在动画执行过程中。 */ [transitionContext completeTransition:!transitionContext.transitionWasCancelled]; }]; } - (void)animationDidStop:(CATransition *)anim finished:(BOOL)flag { [_transitionContext completeTransition:!_transitionContext.transitionWasCancelled]; } @end

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。

原文链接：http://www.jianshu.com/p/1e4d342ef7ac