iOS实现导航栏透明示例代码

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]};

-(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]};}

-(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"];}

@property (nonatomic, strong) NavigationInteractiveTransition *navT;

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:)];

- (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];}

#import <UIKit/UIKit.h>@class UIViewController, UIPercentDrivenInteractiveTransition;@interface NavigationInteractiveTransition : NSObject <UINavigationControllerDelegate>- (instancetype)initWithViewController:(UIViewController *)vc;- (void)handleControllerPop:(UIPanGestureRecognizer *)recognizer;- (UIPercentDrivenInteractiveTransition *)interactivePopTransition;@end

#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

#import <Foundation/Foundation.h>#import <UIKit/UIKit.h>@interface PopAnimation : NSObject <UIViewControllerAnimatedTransitioning>@end

#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