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Question

我們如何實現“入紙”效果。 我里面有一個containerview和3viewconroller。 我們可以實現以下相同的東西嗎？

這是手套聊天相機的移動效果

Answer 1

我認為您必須閱讀此問題。

https://www.objc.io/issues/12-animations/custom-container-view-controller-transitions/

首先了解前兩個階段。

然后從github下載第3階段：收縮包裝代碼。 在該代碼下，最后用以下代碼替換“ PrivateAnimatedTransition”實現。

@implementation PrivateAnimatedTransition

static CGFloat const kChildViewPadding = 16;
static CGFloat const kDamping = 0.75;
static CGFloat const kInitialSpringVelocity = 0.5;

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
    return 0.3;
}

/// Slide views horizontally, with a bit of space between, while fading out and in.
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {

    UIView *containerView = [transitionContext containerView];

    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    //UIButton *button = fromViewController.button;

    [containerView addSubview:toViewController.view];

    CGRect buttonFrame = CGRectMake(300, 450, 10, 10);

    UIBezierPath *circleMaskPathInitial = [UIBezierPath bezierPathWithOvalInRect:buttonFrame];
    CGPoint extremePoint = CGPointMake(305, 455);
    CGFloat radius = sqrt((extremePoint.x * extremePoint.x) + (extremePoint.y * extremePoint.y));
    UIBezierPath *circleMaskPathFinal = [UIBezierPath bezierPathWithOvalInRect:CGRectInset(buttonFrame, -radius, -radius)];

    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.path = circleMaskPathFinal.CGPath;
    toViewController.view.layer.mask = maskLayer;

    CABasicAnimation *maskLayerAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
    maskLayerAnimation.fromValue = (__bridge id _Nullable)(circleMaskPathInitial.CGPath);
    maskLayerAnimation.toValue = (__bridge id _Nullable)(circleMaskPathFinal.CGPath);
    maskLayerAnimation.duration = [self transitionDuration:transitionContext];
    [maskLayer addAnimation:maskLayerAnimation forKey:@"path"];

    [self performSelector:@selector(finishTransition:) withObject:transitionContext afterDelay:[self transitionDuration:transitionContext]];
}

- (void)finishTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
    [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey].view.layer.mask = nil;
}

和您完成的“ BINGO”。 只需將buttonFrame替換為實際選擇的索引按鈕的框架即可。 隨時提出任何疑問