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- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext

- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                          interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);

- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                   animationControllerForOperation:(UINavigationControllerOperation)operation
                                                fromViewController:(UIViewController *)fromVC
                                                  toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

#import <Foundation/Foundation.h>
@class TransitionPushAnimation;
@class TransitionPopAnimation;

@interface TransitionNavigationPerformer : NSObject <UINavigationControllerDelegate>

- (instancetype)initWithNav:(id)nav; //為了操控 self.navigationController

@property (weak, nonatomic)  UINavigationController *navigationController; //這里強(qiáng)調(diào)單項弱引用 

@property (strong, nonatomic) TransitionPushAnimation *pushAnimation;

@property (strong, nonatomic) TransitionPopAnimation *popAnimation;

@property (strong, nonatomic) UIPercentDrivenInteractiveTransition *interactionController;//沒做特殊處理 就是默認(rèn)系統(tǒng)創(chuàng)建 用來控制動畫效果進(jìn)度狀態(tài)

@end

//
//  TransitionNavigationPerformer.m
//  SectionDemo
//
//  Created by HF on 17/3/29.
//  Copyright ? 2017年 HF-Liqun. All rights reserved.
//

#import "TransitionNavigationPerformer.h"
#import "TransitionPopAnimation.h"
#import "TransitionPushAnimation.h"

@interface TransitionNavigationPerformer ()
{
    UIScreenEdgePanGestureRecognizer *panGesture;
}

@end

@implementation TransitionNavigationPerformer

- (instancetype)initWithNav:(id)nav
{
    self = [super init];
    if (self) {
        
        self.navigationController = nav;
        // 在導(dǎo)航控制器的視圖上添加pan手勢 --> 需要從邊緣進(jìn)行拖動，在控制器轉(zhuǎn)換的時候是有用 "UIScreenEdgePanGestureRecognizer"
        panGesture = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
        panGesture.edges = UIRectEdgeLeft; //主要用作返回 left
        [self.navigationController.view addGestureRecognizer:panGesture];
        
        // 初始化動畫方案
        self.pushAnimation = [[TransitionPushAnimation alloc] init];
        self.popAnimation  = [[TransitionPopAnimation alloc] init];
    }
    return self;
}

- (void)dealloc
{   //這里目的防止取消切換效果后 導(dǎo)航控制器仍然會對手勢持有
    [panGesture removeTarget:self action:@selector(pan:)];
    self.interactionController = nil;
}

- (void)pan:(UIScreenEdgePanGestureRecognizer *)recognizer
{
    UIView *view = self.navigationController.view;
    CGFloat progress = [recognizer translationInView:view].x / (view.bounds.size.width * 1.0);
    progress = MIN(1.0, MAX(0.0, progress));
    
    if (recognizer.state == UIGestureRecognizerStateBegan) {
        // 創(chuàng)建過渡對象，彈出viewController
        self.interactionController = [[UIPercentDrivenInteractiveTransition alloc] init];
        [self.navigationController popViewControllerAnimated:YES];
    }
    else if (recognizer.state == UIGestureRecognizerStateChanged) {
        // 更新 interactive transition 的進(jìn)度
        [self.interactionController updateInteractiveTransition:progress];
    }
    else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {
        // 完成或者取消過渡
        if (progress > 0.5) { 
            [self.interactionController finishInteractiveTransition];
        }
        else {
            [self.interactionController cancelInteractiveTransition];
        }
        self.interactionController = nil;
    }
}

#pragma mark - UINavigationControllerDelegate

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                  animationControllerForOperation:(UINavigationControllerOperation)operation
                                               fromViewController:(UIViewController *)fromVC
                                                 toViewController:(UIViewController *)toVC
{
    if (operation == UINavigationControllerOperationPush) {
        return self.pushAnimation;
    }
    else if (operation == UINavigationControllerOperationPop) {
        return self.popAnimation;
    }
    return nil;
}

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                         interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController {
    // 檢查是否是我們的自定義過渡
    if ([animationController isKindOfClass:[TransitionPushAnimation class]] || [animationController isKindOfClass:[TransitionPopAnimation class]]) {
        return self.interactionController;
    }
    else {
        return nil;
    }
}

@end