自iOS7開始，蘋果支持自定義轉(zhuǎn)場動畫；
完整Demo：HHTransitionAnimator

若需自定義A控制器到B控制器的轉(zhuǎn)場動畫，則實現(xiàn)步驟如下：

• 第一步：自定義對象HHTransitionAnimator，自定義轉(zhuǎn)場動畫

@interface HHTransitionAnimator : UIPercentDrivenInteractiveTransition <UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate>

@end

@implementation HHTransitionAnimator


 /** 轉(zhuǎn)場動畫時長 */
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;
{
    return 0.3;
}

 /** 轉(zhuǎn)場動畫具體實現(xiàn) - 這里是一個漸變效果 */
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;
{
   UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
    [[transitionContext containerView] addSubview:toView];
    toView.alpha = 0;
    [UIView animateWithDuration:weakSelf.transitionDuration animations:^{
      toView.alpha = 1;
    }completion:^(BOOL finished) {
      [transitionContext completeTransition:YES];
    }];
}

#pragma mark - UIViewControllerTransitioningDelegate
/** 自定義present動畫 */
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return self;
}
@end

• 第二步：使用自定義轉(zhuǎn)場動畫

// A present -> B

@interface ListViewController : UIViewController

@property (nonatomic, strong) HHTransitionAnimator *animator; 

...

- (void)onClick
{
    UIViewController *vc = [UIViewController new];
    vc.transitioningDelegate = self.animator; //指定負責轉(zhuǎn)場動畫的對象
    vc.modalPresentationStyle = UIModalPresentationCustom;
    [self presentViewController:vc animated:YES completion:nil];
}
@end

至此，一個簡單的自定義present轉(zhuǎn)場動畫就做好了，當然還有自定義dismiss動畫，手勢驅(qū)動返回，我們一一道來：

• 自定義dismiss動畫
  1.實現(xiàn)animationControllerForDismissedController代理方法，返回負責dismiss動畫的對象，這里返回自己
  2.又因為present和dismiss動畫都會來這里：animateTransition:，所以搞個transitionType加以區(qū)分，修改后的代碼如下

@implementation HHTransitionAnimator

...

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;
{
    if(self.transitionType == HHViewControllerTransitionTypeDismiss){
        //dismiss動畫
    }else{
      //present動畫
    }
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    self.transitionType = HHViewControllerTransitionTypePresent;
    return self;
}
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    self.transitionType = HHViewControllerTransitionTypeDismiss;
    return self;
}

• 手勢驅(qū)動返回，這里簡單實現(xiàn)一個左滑返回效果
  1.相信細心的同學已經(jīng)發(fā)現(xiàn)了，我們自定義的HHTransitionAnimator是繼承自UIPercentDrivenInteractiveTransition的，通過繼承這個類，可以方便地根據(jù)滑動距離來控制dismiss動畫完成的比例
  2.給需要滑動返回的控制器view添加手勢，根據(jù)手勢滑動距離更新dismiss動畫比例
  3.實現(xiàn)interactionControllerForDismissal代理方法：當處于滑動返回狀態(tài)時才返回自己，否則返回nil；
  4.用interacting屬性來標識是否處于滑動返回中

- (void)addGestureToViewController:(UIViewController *)vc
{
    UIScreenEdgePanGestureRecognizer *ges = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];
    ges.edges = UIRectEdgeLeft;
    [vc.view addGestureRecognizer:ges];
}
- (void)handleGesture:(UIScreenEdgePanGestureRecognizer *)ges
{
    CGFloat progress = [ges translationInView:ges.view].x / ges.view.bounds.size.width;
    
    switch (ges.state) {
        case UIGestureRecognizerStateBegan:
        {
            self.interacting = YES;
            [self.gestureVC dismissViewControllerAnimated:YES completion:nil];
        }
            break;
        case UIGestureRecognizerStateChanged:
        {
            [self updateInteractiveTransition:progress]; //更新頁面返回進度
        }
            break;
        case UIGestureRecognizerStateEnded:
        {
            self.interacting = NO;
            if (progress < 0.3) {
                [self cancelInteractiveTransition];  //滑動距離過短，取消頁面返回
            }else{
                [self finishInteractiveTransition];  //達到滑動返回距離，繼續(xù)執(zhí)行頁面返回動畫
            }
        }
            break;
        default: break;
    }
}

#pragma mark - UIViewControllerTransitioningDelegate
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator;
{
    return self.interacting ? self : nil;
}

@end

最后，封裝一下方便使用：

@interface UIViewController (HHTransitionAnimator)

- (void)hh_presentViewController:(UIViewController *)vc animated:(BOOL)flag TransitionAnimator:(HHTransitionAnimator *)animator completion:(void (^ __nullable)(void))completion;

@end

@implementation UIViewController (HHTransitionAnimator)

- (void)hh_presentViewController:(UIViewController *)vc animated:(BOOL)flag TransitionAnimator:(HHTransitionAnimator *)animator completion:(void (^ __nullable)(void))completion;
{
    self.hh_transitionAnimator = animator;
    self.hh_transitionAnimator.gestureVC = vc;
    vc.transitioningDelegate = self.hh_transitionAnimator;
    vc.modalPresentationStyle = UIModalPresentationCustom;
    dispatch_async(dispatch_get_main_queue(), ^{
        [self presentViewController:vc animated:flag completion:completion];
    });
}


#pragma mark - getter & setter
- (void)setHh_transitionAnimator:(HHTransitionAnimator *)hh_transitionAnimator
{
    objc_setAssociatedObject(self, @selector(hh_transitionAnimator), hh_transitionAnimator, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (HHTransitionAnimator *)hh_transitionAnimator
{
    return objc_getAssociatedObject(self, @selector(hh_transitionAnimator));
}

@end

使用的時候只需要調(diào)用
- (void)hh_presentViewController:animated:TransitionAnimator:completion:方法即可