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iOS實現(xiàn)導(dǎo)航欄透明示例代碼

 更新時間：2017年03月30日 09:54:01   作者：強強劉  
本篇文章主要介紹了iOS實現(xiàn)導(dǎo)航欄透明示例代碼，小編覺得挺不錯的，現(xiàn)在分享給大家，也給大家做個參考。一起跟隨小編過來看看吧

在最近一個項目中碰到這樣一個場景,在被push進來的一個頁面設(shè)置導(dǎo)航欄透明,且要求控制對tableview組的頭視圖進行懸停顯示,nav隨著tableview偏移量改變透明度,當(dāng)然這樣的需求確實不是什么難事,但是如果當(dāng)前頁面繼續(xù)push一個不需要此類效果的頁面,當(dāng)在返回當(dāng)前頁面的時候就會出現(xiàn)一個坑,nav的展示很突兀,下面是直接上解決方法...ps:假設(shè)A頁面為需要設(shè)置透明,B頁面被Apush且不需要設(shè)置透明

首先在需要設(shè)置導(dǎo)航欄透明的頁面的viewDidload中寫上

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;
  //設(shè)置狀態(tài)欄
  [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
  //設(shè)置標(biāo)題顏色
  self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor clearColor]};

在scrollViewDidScroll代理方法中

-(void)scrollViewDidScroll:(UIScrollView *)scrollView {

  CGFloat offset = scrollView.contentOffset.y;
  //根據(jù)自己需要設(shè)置(136)的大小
  CGFloat alpha = offset / 136;
  _barImageView.alpha = alpha;
  //記錄下當(dāng)前的透明度,在返回當(dāng)前頁面時需要
  _alpha = alpha;
  [[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithFloat:alpha] forKey:@"_alpha"];
  //設(shè)置標(biāo)題的透明度
  self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor colorWithWhite:0 alpha:alpha]};
}

當(dāng)前頁的viewWillAppear, viewDidAppear, viewWillDisappear

-(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"];
}

那么在我們需要push的下一個頁面需要什么操作呢,我們需要在這個頁面顯示正常的nav并且禁掉系統(tǒng)的手勢pop,自己寫一個pop手勢,以方便我們拿到pop滑動時的偏移量,在做的時候使用了兩個類,在最后會有源碼貼出

B.m 須遵守UIGestureRecognizerDelegate,并導(dǎo)入NavigationInteractiveTransition.h

全局變量

@property (nonatomic, strong) NavigationInteractiveTransition *navT;

viewDidLoad

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

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
  //記錄當(dāng)前是是否是通過手勢滑動回去
  [[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithBool:YES] forKey:@"isGesturePop"];
  /**
   * 這里有兩個條件不允許手勢執(zhí)行，1、當(dāng)前控制器為根控制器；2、如果這個push、pop動畫正在執(zhí)行（私有屬性）
   */
  return self.navigationController.viewControllers.count != 1 && ![[self.navigationController valueForKey:@"_isTransitioning"] boolValue];
}

需要依賴的兩個類源碼

NavigationInteractiveTransition.h

#import <UIKit/UIKit.h>

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

NavigationInteractiveTransition.m

#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;
}

/**
 * 我們把用戶的每次Pan手勢操作作為一次pop動畫的執(zhí)行
 */
- (void)handleControllerPop:(UIPanGestureRecognizer *)recognizer {
  /**
   * interactivePopTransition就是我們說的方法2返回的對象，我們需要更新它的進度來控制Pop動畫的流程，我們用手指在視圖中的位置與視圖寬度比例作為它的進度。
   */
  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);
  /**
   * 穩(wěn)定進度區(qū)間，讓它在0.0（未完成）～1.0（已完成）之間
   */
  progress = MIN(1.0, MAX(0.0, progress));
  if (recognizer.state == UIGestureRecognizerStateBegan) {
    /**
     * 手勢開始，新建一個監(jiān)控對象
     */
    self.interactivePopTransition = [[UIPercentDrivenInteractiveTransition alloc] init];
    /**
     * 告訴控制器開始執(zhí)行pop的動畫
     */
    [self.vc popViewControllerAnimated:YES];
  }
  else if (recognizer.state == UIGestureRecognizerStateChanged) {

    /**
     * 更新手勢的完成進度
     */
    [self.interactivePopTransition updateInteractiveTransition:progress];
  }
  else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {

    /**
     * 手勢結(jié)束時如果進度大于一半，那么就完成pop操作，否則重新來過。
     */
    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中判斷如果當(dāng)前執(zhí)行的是Pop操作，就返回我們自定義的Pop動畫對象。
   */
  if (operation == UINavigationControllerOperationPop)
    return [[PopAnimation alloc] init];

  return nil;
}

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
             interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController {

  /**
   * 方法2會傳給你當(dāng)前的動畫對象animationController，判斷如果是我們自定義的Pop動畫對象，那么就返回interactivePopTransition來監(jiān)控動畫完成度。
   */
  if ([animationController isKindOfClass:[PopAnimation class]])
    return self.interactivePopTransition;

  return nil;
}

@end

PopAnimation.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface PopAnimation : NSObject <UIViewControllerAnimatedTransitioning>

@end

PopAnimation.m

#import "PopAnimation.h"

@interface PopAnimation ()
@property (nonatomic, strong) id <UIViewControllerContextTransitioning> transitionContext;
@end

@implementation PopAnimation

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
  //這個方法返回動畫執(zhí)行的時間
  return 0.25;
}

/**
 * transitionContext你可以看作是一個工具，用來獲取一系列動畫執(zhí)行相關(guān)的對象，并且通知系統(tǒng)動畫是否完成等功能。
 */
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
  /**
   * 獲取動畫來自的那個控制器
   */
  UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
  /**
   * 獲取轉(zhuǎn)場到的那個控制器
   */
  UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

  /**
   * 轉(zhuǎn)場動畫是兩個控制器視圖時間的動畫，需要一個containerView來作為一個“舞臺”，讓動畫執(zhí)行。
   */
  UIView *containerView = [transitionContext containerView];
  [containerView insertSubview:toViewController.view belowSubview:fromViewController.view];

  NSTimeInterval duration = [self transitionDuration:transitionContext];

  /**
   * 執(zhí)行動畫，我們讓fromVC的視圖移動到屏幕最右側(cè)
   */
  [UIView animateWithDuration:duration animations:^{
    fromViewController.view.transform = CGAffineTransformMakeTranslation([UIScreen mainScreen].bounds.size.width, 0);
  }completion:^(BOOL finished) {
    /**
     * 當(dāng)你的動畫執(zhí)行完成，這個方法必須要調(diào)用，否則系統(tǒng)會認(rèn)為你的其余任何操作都在動畫執(zhí)行過程中。
     */
    [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內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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