冬天已经过去了,阳光越 来越暖洋洋的了。还记得上学的时候,老师总说“春天是播种的季节”,而我还 没在朋友圈许下什么愿望。一年了,不敢想 象回首还能看到点什么,所以勇往直前。当被俗世所扰,你是否也丢失了自己,忘却了理想。

欲做精金美玉的人品,定从烈火中煅来;
思立掀天揭地的事功,须向薄冰上履过。

大数据培训,云培训,数据挖掘培训,云计算培训,高端软件开发培训,项目经理培训

这篇博客中,我们主 要来叙述一下上述动画效果的实现方案。主要涉及 View Controller 转场动画的知识。

Presenting a View Controller

显示一个 View Controller 主要有一下几种方式:

  • 使用 segues 自动显示 View Controller;

  • 使用 showViewController:sender: 和 showDetailViewController:sender: 方法显示 View Controller;

  • 调用 presentViewController:animated:completion: 方法依模态形式显示 View Controller

通过上述方式,我们可以将一个 View Controller 显示出来,而对于显示地形式,我们可以使用 UIKit 中预定义的形式,也可以自定义(即自定义转场动画)。

Customizing the Transition Animations

自定义转场动画中,主要包 含以下几个组件:

  • Presenting View Controller(正在显示的 View Controller)

  • Animator(动画管理者)

  • Presented View Controller(要显示的 View Controller)

  • Transitioning Delegate Object(转场代理,用来提供 Animator 对象)

实现自定义转场动画,通常按 照以下几个步骤来完成

  • 创建 Presented View Controller;

  • 创建 Animator;

  • 设置 Presented View Controller 的 transitioningDelegate 属性,并实现 UIViewControllerTransitioningDelegate 提供 Animator 对象;

  • 在 Presenting View Controller 中调用 presentViewController:animated:completion: 显示 Presented View Controller;

Presented View Controller

这里,我们将 Presented View Controller 本身作为其转场代理,你也可 以使用单独的代理对象。

class PresentedViewController: UIViewController {    let imageView = UIImageView(image: UIImage(named: "jd_add.jpg"))    override func viewDidLoad() {        super.viewDidLoad()        // 1.设置 transitioningDelegate(转场代理)
        transitioningDelegate = self
        modalPresentationStyle = .custom
        view.addSubview(imageView)
    }    override func viewDidLayoutSubviews() {        super.viewDidLayoutSubviews()
        imageView.frame = CGRect(x: 0, y: 120, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height - 120)
    }    override func touchesBegan(_ touches: Set, with event: UIEvent?) {        self.dismiss(animated: true, completion: nil)
    }
}

Animator

Animator 作为转 场动画的管理者,主要负责 Presenting 和 Dismissing 动画效果。

动画时长

/// 转场动画时长func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {    return TimeInterval(0.5)
}

执行动画

/// 执行转场动画func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {    switch type {    case .Present:
        present(transitionContext: transitionContext)    case .Dismiss:
        dismiss(transitionContext: transitionContext)
    }
}

Presenting 动画

/// Presenting 动画func present(transitionContext: UIViewControllerContextTransitioning) {    /** 1.从转场上下文中取出 Presenting/Pressented View Controller 及容器视图 */
    guard let presentingVC = transitionContext.viewController(forKey: .from) as? ViewController else {        return
    }    guard let presentedVC = transitionContext.viewController(forKey: .to) as? PresentedViewController else {        return
    }    let containerView = transitionContext.containerView    /** 2.设置 Presenting View Controller 所显示内容的属性 */
    // 对 presentingVC 的视图内容截屏,用于 presentedVC 显示出来时的背景
    guard let presentingVCViewSnapshot = presentingVC.view.snapshotView(afterScreenUpdates: false) else {        return
    }    // 隐藏 presentingVC 的 view,并将其截屏添加到 containerView 中
    presentingVC.view.isHidden = true
    containerView.addSubview(presentingVCViewSnapshot)    // 改变 presentingVCViewSnapshot 的焦点
    presentingVCViewSnapshot.layer.anchorPoint = CGPoint(x: 0.5, y: 1)    // 更新 presentingVCViewSnapshot 的 frame
    presentingVCViewSnapshot.frame = presentingVC.view.frame    /** 3.设置 Presented View Controller 所显示内容的属性 */
    presentedVC.view.frame = CGRect(x: 0, y: containerView.bounds.height, width: containerView.bounds.width, height: containerView.bounds.height)
    containerView.addSubview(presentedVC.view)    /** 4.设置 Presenting 转场动画 */
    UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {        // 改变 presentingVCViewSnapshot 的 layer 的 transform,使其绕 X轴 旋转,并改变大小
        presentingVCViewSnapshot.layer.transform.m34 = -1 / 100.0
        presentingVCViewSnapshot.layer.transform = presentingVCViewSnapshot.layer.transform = CATransform3DConcat(CATransform3DMakeRotation(CGFloat(0.1), 1, 0, 0), CATransform3DMakeScale(0.85, 0.95, 1))        // 改变 presentedVC 的 view 的 transform
        presentedVC.view.transform = CGAffineTransform(translationX: 0, y: -containerView.bounds.height)
    }) { (finished) in
        // 告知 UIKit Presenting 转场动画结束(很重要)
        transitionContext.completeTransition(true)
    }
}

Dismissing 动画

/// Dismissing 动画func dismiss(transitionContext: UIViewControllerContextTransitioning) {    /** 1.从转场
上下文中取出容器视图、Presenting/Pressented View Controller 及其 view 的截屏 */
    let containerView = transitionContext.containerView    guard let presentingVC = transitionContext.viewController(forKey: .from) as? PresentedViewController else {        return
    }    guard let presentedVC = transitionContext.viewController(forKey: .to) as? ViewController else {        return
    }    let subviewsCount = containerView.subviews.count
    let presentedVCViewSnapshot = containerView.subviews[subviewsCount - 2]    /** 2.设置 Dismissing 转场动画 */
    UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {        // 将 presentedVCViewSnapshot 的 transform 恢复到初始值
        presentedVCViewSnapshot.layer.transform = CATransform3DIdentity
        // 将 presentedVC 的 view 的 transform 恢复到初始值
        presentingVC.view.transform = CGAffineTransform.identity
    }) { (finished) in
        // 使 presentedVC 的 view 显示出来,并隐藏其截屏
        presentedVC.view.isHidden = false
        presentedVCViewSnapshot.removeFromSuperview()        // 告知 UIKit Dismissing 转场动画结束(很重要)
        transitionContext.completeTransition(true)
    }
}

Transitioning Delegate

// MARK: - 2.实现 UIViewControllerTransitioningDelegate 提供 Animatorextension PresentedViewController: UIViewControllerTransitioningDelegate {    /// Present
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {        return MyAnimator(type: .Present)
    }    /// Dismiss
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {        return MyAnimator(type: .Dismiss)
    }
}

Present

@IBAction func present() {    let presentedVC = PresentedViewController()
    present(presentedVC, animated: true, completion: nil)
}

关于 View Controller Transition 就介绍到这里,你应该 熟悉了其使用方法,至于博 客中的动画效果,我想就没办法深究了,这是一 个花费时间苦差事。



分类: