ios - 如何检测正在 WKWebView 中播放的电影？

Question

我想知道是否可以检测到正在 WKWebView 中播放的电影？

另外我想知道打开的流的确切 URL？

Answer 1

由于这个问题的解决方案需要大量的研究和不同的方法，所以我想在这里记录它以供其他人遵循我的想法。 如果您只对最终解决方案感兴趣，请寻找一些花哨的标题。

我开始使用的应用非常简单。这是一个导入 WebKit 并打开一个带有一些 NSURL 的 WKWebView 的单 View 应用程序:

import UIKit
import WebKit
class ViewController: UIViewController {
    var webView: WKWebView!

    override func viewDidAppear(animated: Bool) {
        webView = WKWebView()
        view = webView
        let request = NSURLRequest(URL: NSURL(string: "http://tinas-burger.tumblr.com/post/133991473113")!)
        webView.loadRequest(request) 
    }
}

The URL includes a video that is (kind of) protected by JavaScript. I really haven't seen the video yet, it was just the first I discovered. Remember to add NSAppTransportSecurity and NSAllowsArbitraryLoads to your Info.plist or you will see a blank page.

WKNavigationDelegate

WKNavigationDelegate 不会通知您正在播放视频。因此设置 webView.navigationDelegate = self 并实现协议(protocol)不会给您带来预期的结果。

NSNotificationCenter

我假设一定有像 SomeVideoPlayerDidOpen 这样的事件。不幸的是没有，但它可能有一个 SomeViewDidOpen 事件，所以我开始检查 View 层次结构:

UIWindow
    UIWindow
        WKWebView
            WKScrollView
            ...
        ...
UIWindow
    UIWindow
        UIView
            AVPlayerView
        UITransitionView
            UIView
                UIView
                    UIView
                        ...
                    UIView
                        ...
                    AVTouchIgnoringView
                        ...

正如预期的那样，将添加一个额外的 UIWindow，它可能有一个事件，他妈的是的，它确实有!

我通过添加一个新的观察者扩展了 viewDidAppear::

NSNotificationCenter.defaultCenter().addObserver(self, selector: "windowDidBecomeVisible:", name: UIWindowDidBecomeVisibleNotification, object: nil)

并添加了相应的方法:

func windowDidBecomeVisible(notification: NSNotification) {
    for mainWindow in UIApplication.sharedApplication().windows {
        for mainWindowSubview in mainWindow.subviews {
            // this will print:
            // 1: `WKWebView` + `[WKScrollView]`
            // 2: `UIView` + `[]`
            print("\(mainWindowSubview) \(mainWindowSubview.subviews)")
}

正如我们预期的那样，它返回了我们之前检查过的 View 层次结构。但不幸的是，AVPlayerView 似乎将在稍后创建。

如果您相信您的应用程序将打开的唯一 UIWindow 是媒体播放器，那么此时您就完成了。但是这个解决方案不会让我晚上睡不着觉，所以让我们更深入一点......

注入(inject)一个事件

我们需要得到有关 AVPlayerView 被添加到这个无名 UIView 的通知。很明显 AVPlayerView 必须是 UIView 的子类，但由于它没有被 Apple 正式记录，我检查了 iOS Runtime Headers for AVPlayerView它绝对是 UIView。

现在我们知道 AVPlayerView 是 UIView 的子类，它可能会通过调用 addSubview 添加到无名的 UIView 中: 。所以我们必须得到有关添加的 View 的通知。不幸的是 UIView 没有提供一个事件来观察这个。但它确实调用了一个名为 didAddSubview: 的方法，这可能非常方便。

所以让我们检查一下 AVPlayerView 是否会添加到我们的应用程序中的某处并发送通知:

let originalDidAddSubviewMethod = class_getInstanceMethod(UIView.self, "didAddSubview:")
let originalDidAddSubviewImplementation = method_getImplementation(originalDidAddSubviewMethod)

typealias DidAddSubviewCFunction = @convention(c) (AnyObject, Selector, UIView) -> Void
let castedOriginalDidAddSubviewImplementation = unsafeBitCast(originalDidAddSubviewImplementation, DidAddSubviewCFunction.self)

let newDidAddSubviewImplementationBlock: @convention(block) (AnyObject!, UIView) -> Void = { (view: AnyObject!, subview: UIView) -> Void in
    castedOriginalDidAddSubviewImplementation(view, "didAddsubview:", subview)

    if object_getClass(view).description() == "AVPlayerView" {
        NSNotificationCenter.defaultCenter().postNotificationName("PlayerWillOpen", object: nil)
    }
}

let newDidAddSubviewImplementation = imp_implementationWithBlock(unsafeBitCast(newDidAddSubviewImplementationBlock, AnyObject.self))
method_setImplementation(originalDidAddSubviewMethod, newDidAddSubviewImplementation)

现在我们可以观察通知并接收相应的事件:

NSNotificationCenter.defaultCenter().addObserver(self, selector: "playerWillOpen:", name: "PlayerWillOpen", object: nil)

func playerWillOpen(notification: NSNotification) {
    print("A Player will be opened now")
}

更好的通知注入(inject)

由于 AVPlayerView 不会被删除，而只会被释放，我们将不得不稍微重写我们的代码并向 AVPlayerViewController 注入(inject)一些通知。这样我们就可以收到任意多的通知，例如:PlayerWillAppear 和 PlayerWillDisappear:

let originalViewWillAppearMethod = class_getInstanceMethod(UIViewController.self, "viewWillAppear:")
let originalViewWillAppearImplementation = method_getImplementation(originalViewWillAppearMethod)

typealias ViewWillAppearCFunction = @convention(c) (UIViewController, Selector, Bool) -> Void
let castedOriginalViewWillAppearImplementation = unsafeBitCast(originalViewWillAppearImplementation, ViewWillAppearCFunction.self)

let newViewWillAppearImplementationBlock: @convention(block) (UIViewController!, Bool) -> Void = { (viewController: UIViewController!, animated: Bool) -> Void in
    castedOriginalViewWillAppearImplementation(viewController, "viewWillAppear:", animated)

    if viewController is AVPlayerViewController {
        NSNotificationCenter.defaultCenter().postNotificationName("PlayerWillAppear", object: nil)
    }
}

let newViewWillAppearImplementation = imp_implementationWithBlock(unsafeBitCast(newViewWillAppearImplementationBlock, AnyObject.self))
method_setImplementation(originalViewWillAppearMethod, newViewWillAppearImplementation)

let originalViewWillDisappearMethod = class_getInstanceMethod(UIViewController.self, "viewWillDisappear:")
let originalViewWillDisappearImplementation = method_getImplementation(originalViewWillDisappearMethod)

typealias ViewWillDisappearCFunction = @convention(c) (UIViewController, Selector, Bool) -> Void
let castedOriginalViewWillDisappearImplementation = unsafeBitCast(originalViewWillDisappearImplementation, ViewWillDisappearCFunction.self)

let newViewWillDisappearImplementationBlock: @convention(block) (UIViewController!, Bool) -> Void = { (viewController: UIViewController!, animated: Bool) -> Void in
    castedOriginalViewWillDisappearImplementation(viewController, "viewWillDisappear:", animated)

    if viewController is AVPlayerViewController {
        NSNotificationCenter.defaultCenter().postNotificationName("PlayerWillDisappear", object: nil)
    }
}

let newViewWillDisappearImplementation = imp_implementationWithBlock(unsafeBitCast(newViewWillDisappearImplementationBlock, AnyObject.self))
method_setImplementation(originalViewWillDisappearMethod, newViewWillDisappearImplementation)

现在我们可以观察到这两个通知，一切顺利:

 NSNotificationCenter.defaultCenter().addObserver(self, selector: "playerWillAppear:", name: "PlayerWillAppear", object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "playerWillDisappear:", name: "PlayerWillDisappear", object: nil)

func playerWillAppear(notification: NSNotification) {
    print("A Player will be opened now")
}

func playerWillDisappear(notification: NSNotification) {
    print("A Player will be closed now")
}

视频地址

我花了几个小时挖掘一些 iOS Runtime Headers 来猜测在哪里可以找到指向视频的 URL，但我无法找到它。当我深入研究 WebKit 本身的一些源文件时，我不得不放弃并接受没有简单的方法来做到这一点，尽管我相信它隐藏在某个地方并且可以到达，但很可能只有付出了很多努力。