自定义dismiss转场动画，实现和pop一样的效果

自定义dismiss转场动画，实现和pop一样的效果，如果想实现其他的效果基本思路也差不多

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1、首先实现dismissViewControllerAnimated动画，新建一个DismissTransitionAnimated类继承自NSObject，并遵守UIViewControllerAnimatedTransitioning协议
DismissTransitionAnimated.h文件

#import 

@interface DismissTransitionAnimated : NSObject

@end

DismissTransitionAnimated.m文件

#import "DismissTransitionAnimated.h"

#import 
@interface DismissTransitionAnimated ()

@end
@implementation DismissTransitionAnimated

/** 动画时间 */
- (NSTimeInterval)transitionDuration:(id)transitionContext{
    return 1.0;
}

/** 定义动画 */
- (void)animateTransition:(id)transitionContext{
    
    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    UIView *containerView = [transitionContext containerView];
    UIView *fromView = nil;
    UIView *toView = nil;
    
    if ([transitionContext respondsToSelector:@selector(viewForKey:)]) {
        fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
        toView = [transitionContext viewForKey:UITransitionContextToViewKey];
    }else{
        fromView = fromViewController.view;
        toView = toViewController.view;
    }
    
    BOOL isDismiss = (fromViewController.presentingViewController == toViewController);
    
    CGRect fromFrame = [transitionContext initialFrameForViewController:fromViewController];
    CGRect toFrame = [transitionContext finalFrameForViewController:toViewController];
    
    if (isDismiss) {
        fromView.frame = fromFrame;
        toView.frame = CGRectOffset(toFrame, toFrame.size.width*0.3*-1, 0);
       [containerView insertSubview:toView belowSubview:fromView];
    }
    
    NSTimeInterval transitionDuration = [self transitionDuration:transitionContext];
    
    [UIView animateWithDuration:transitionDuration animations:^{
        if (isDismiss) {
            toView.frame = toFrame;
            fromView.frame = CGRectOffset(fromFrame, fromFrame.size.width, 0);
        }
    } completion:^(BOOL finished) {
        BOOL isCancel = [transitionContext transitionWasCancelled];
        if (isCancel) {
            [toView removeFromSuperview];
        }
        [transitionContext completeTransition:!isCancel];
    }];
}

2、新建控制器ViewController， 并遵守UIViewControllerTransitioningDelegate
定义属性

@property (retain, nonatomic) UIPercentDrivenInteractiveTransition *percentDrivenTransition;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
UIViewController *presentVC = [[UIViewController alloc]init];
    presentVC.transitioningDelegate = self;
    presentVC.view.backgroundColor = [UIColor redColor];
    [self addScreenLeftEdgePanGestureRecognizer:presentVC.view];
    [self presentViewController:presentVC animated:YES completion:nil];
}

- (nullable id )animationControllerForDismissedController:(UIViewController *)dismissed {
    return [[DismissTransitionAnimated alloc] init];
}
- (id)interactionControllerForPresentation:(id)animator{
    return _percentDrivenTransition;
}

- (id)interactionControllerForDismissal:(id)animator{
    return _percentDrivenTransition;
}

presentVC添加左边边缘滑动返回

- (void)addScreenLeftEdgePanGestureRecognizer:(UIView *)view{
    UIScreenEdgePanGestureRecognizer *screenEdgePan = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self action:@selector(edgePanGesture:)];
    screenEdgePan.edges = UIRectEdgeLeft;
    [view addGestureRecognizer:screenEdgePan];
}

- (void)edgePanGesture:(UIScreenEdgePanGestureRecognizer *)edgePan{
    CGFloat progress = fabs([edgePan translationInView:[UIApplication sharedApplication].keyWindow].x/[UIApplication sharedApplication].keyWindow.bounds.size.width);
    if (edgePan.state == UIGestureRecognizerStateBegan) {
        self.percentDrivenTransition = [[UIPercentDrivenInteractiveTransition alloc]init];
        if (edgePan.edges == UIRectEdgeLeft) {
            [self dismissViewControllerAnimated:YES completion:nil];
        }
    }else if (edgePan.state == UIGestureRecognizerStateChanged){
        [self.percentDrivenTransition updateInteractiveTransition:progress];
    }else if (edgePan.state == UIGestureRecognizerStateEnded || edgePan.state == UIGestureRecognizerStateCancelled){
        if (progress > 0.5) {
            [_percentDrivenTransition finishInteractiveTransition];
        }else{
            [_percentDrivenTransition cancelInteractiveTransition];
        }
        _percentDrivenTransition = nil;
    }
}