iOS导航栏滑动渐变

@property (nonatomic, assign) double aphle;

@property (nonatomic, strong) QMUINavigationBarScrollingAnimator *navigationAnimator;

首先设置页面样式从y=0布局

  if([self respondsToSelector:@selector(edgesForExtendedLayout)]){
        self.edgesForExtendedLayout=UIRectEdgeAll;
    }

实例化QMUINavigationBarScrollingAnimator

- (void)initNavigationAnimator {
    self.navigationAnimator = [[QMUINavigationBarScrollingAnimator alloc] init];
    self.navigationAnimator.scrollView = self.pagerView.mainTableView;/// 绑定的 UIScrollView
    self.navigationAnimator.offsetYToStartAnimation = 30;// contentOffset.y 到达哪个值即开始动画，默认为 0
    self.navigationAnimator.distanceToStopAnimation = NavigationContentTop;/// 控制从 offsetYToStartAnimation 开始，要滚动多长的距离就打到动画结束的位置，默认为 44
}

#pragma mark - <QMUICustomNavigationBarTransitionDelegate>
- (NSString *)customNavigationBarTransitionKey {
    return self.navigationAnimator.progress >= 1 ? nil : NSStringFromClass([self class]);
}

- (BOOL)shouldCustomizeNavigationBarTransitionIfHideable {
    return YES;
}

设置初始导航栏按钮

- (void)setupNavigationItems {
    [super setupNavigationItems];
    
    self.navigationItem.leftBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_white_back"] target:self action:@selector(clickCloseButtonAction)];
    self.navigationItem.rightBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_share"] target:self action:@selector(clickShareButtonAction)];

}

通过scrollview滚动代理设置导航栏的样式

- (void)mainTableViewDidScroll:(UIScrollView *)scrollView {
    if (scrollView.contentOffset.y > 175) {
        self.title = @"平台详情";
        self.navigationItem.leftBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"icons_black_back"] target:self action:@selector(clickCloseButtonAction)];
        self.navigationItem.rightBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_share_black"] target:self action:@selector(clickShareButtonAction)];

    }else{
        self.title = @"";
        self.navigationItem.leftBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_white_back"] target:self action:@selector(clickCloseButtonAction)];
        self.navigationItem.rightBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_share"] target:self action:@selector(clickShareButtonAction)];

    }
    
    self.aphle = scrollView.contentOffset.y/175;
    UIImage *image = [[UIImage qmui_imageWithColor:UIColor.whiteColor] qmui_imageWithAlpha:self.aphle];
    [self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
}

- (void)initNavigationAnimator {
    self.navigationAnimator = [[QMUINavigationBarScrollingAnimator alloc] init];
    self.navigationAnimator.scrollView = self.scrollView;
    self.navigationAnimator.offsetYToStartAnimation = 30;
    self.navigationAnimator.distanceToStopAnimation = NavigationContentTop;
    @weakify(self);
    self.navigationAnimator.backgroundImageBlock = ^UIImage * _Nonnull(QMUINavigationBarScrollingAnimator * _Nonnull animator, float progress) {
        @strongify(self);
        UIImage *image = [UIImage qmui_imageWithColor:UIColor.whiteColor];//HexColor(@"#5CEAD2")
        [self changeNavigationItemStyle:progress];
        return [image qmui_imageWithAlpha:progress];
    };
}

- (void)changeNavigationItemStyle:(CGFloat)progress {
    if(progress >= 0.8){
        self.title = self.serviceName;
        self.navigationItem.leftBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"icon_back_black"] target:self action:@selector(clickCloseButtonAction)];
        self.navigationItem.rightBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_share_black"] target:self action:@selector(clickShareButtonAction)];
    }else{
        self.title = @"";
        self.navigationItem.leftBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"icon_service_back"] target:self action:@selector(clickCloseButtonAction)];
        self.navigationItem.rightBarButtonItem = [UIBarButtonItem qmui_itemWithImage:[UIImage imageNamed:@"ic_share_service"] target:self action:@selector(clickShareButtonAction)];
    }
}