I'm exploring tvOS and I found that Apple offers nice set of templates written using TVML. I'd like to know if a tvOS app that utilises TVML templates can also use UIKit.
Can I mix UIKit and TVMLKit within one app?
I found a thread on Apple Developer Forum but it does not fully answer this question and I am going through documentation to find an answer.
是的你可以。显示 TVML 模板需要您使用控制 JavaScript 上下文的对象：TVApplicationController。
var appController: TVApplicationController?
这个对象有一个与之关联的UINavigationController属性。因此，只要您认为合适，您就可以致电：
let myViewController = UIViewController()
self.appController?.navigationController.pushViewController(myViewController, animated: true)
这允许您将自定义 UIKit 视图控制器推送到导航堆栈上。如果您想返回 TVML 模板，只需将 viewController 从导航堆栈中弹出即可。
如果您想知道如何在 JavaScript 和 Swift 之间进行通信，这里有一个方法可以创建一个名为pushMyView()的 javascript 函数
func createPushMyView(){
//allows us to access the javascript context
appController?.evaluateInJavaScriptContext({(evaluation: JSContext) -> Void in
//this is the block that will be called when javascript calls pushMyView()
let pushMyViewBlock : @convention(block) () -> Void = {
() -> Void in
//pushes a UIKit view controller onto the navigation stack
let myViewController = UIViewController()
self.appController?.navigationController.pushViewController(myViewController, animated: true)
}
//this creates a function in the javascript context called "pushMyView".
//calling pushMyView() in javascript will call the block we created above.
evaluation.setObject(unsafeBitCast(pushMyViewBlock, AnyObject.self), forKeyedSubscript: "pushMyView")
}, completion: {(Bool) -> Void in
//done running the script
})
}
一旦你在 Swift 中调用 createPushMyView()，你就可以在你的 javascript 代码中调用pushMyView()，它会将视图控制器推送到堆栈上。
斯威夫特 4.1 更新
只需对方法名称和转换进行一些简单的更改：
appController?.evaluate(inJavaScriptContext: {(evaluation: JSContext) -> Void in
和
evaluation.setObject(unsafeBitCast(pushMyViewBlock, to: AnyObject.self), forKeyedSubscript: "pushMyView" as NSString)
正如接受的答案中提到的，您可以从 JavaScript 上下文中调用几乎任何 Swift 函数。请注意，顾名思义，setObject:forKeyedSubscript:除了块之外，它还将接受对象（如果它们符合从 JSExport 继承的协议），允许您访问该对象上的方法和属性。这是一个例子
import Foundation
import TVMLKit
// Just an example, use sessionStorage/localStorage JS object to actually accomplish something like this
@objc protocol JSBridgeProtocol : JSExport {
func setValue(value: AnyObject?, forKey key: String)
func valueForKey(key: String) -> AnyObject?
}
class JSBridge: NSObject, JSBridgeProtocol {
var storage: Dictionary<String, String> = [:]
override func setValue(value: AnyObject?, forKey key: String) {
storage[key] = String(value)
}
override func valueForKey(key: String) -> AnyObject? {
return storage[key]
}
}
然后在您的应用控制器中：
func appController(appController: TVApplicationController, evaluateAppJavaScriptInContext jsContext: JSContext) {
let bridge:JSBridge = JSBridge();
jsContext.setObject(bridge, forKeyedSubscript:"bridge");
}
然后你可以在你的 JS 中这样做：bridge.setValue(['foo', 'bar'], "baz")
不仅如此，您还可以覆盖现有元素的视图，或定义要在标记中使用的自定义元素，并使用本机视图支持它们：
// Call lines like these before you instantiate your TVApplicationController
TVInterfaceFactory.sharedInterfaceFactory().extendedInterfaceCreator = CustomInterfaceFactory()
// optionally register a custom element. You could use this in your markup as <loadingIndicator></loadingIndicator> or <loadingIndicator /> with optional attributes. LoadingIndicatorElement needs to be a TVViewElement subclass, and there are three functions you can optionally override to trigger JS events or DOM updates
TVElementFactory.registerViewElementClass(LoadingIndicatorElement.self, forElementName: "loadingIndicator")
快速自定义元素示例：
import Foundation
import TVMLKit
class LoadingIndicatorElement: TVViewElement {
override var elementName: String {
return "loadingIndicator"
}
internal override func resetProperty(resettableProperty: TVElementResettableProperty) {
super.resetProperty(resettableProperty)
}
// API's to dispatch events to JavaScript
internal override func dispatchEventOfType(type: TVElementEventType, canBubble: Bool, cancellable isCancellable: Bool, extraInfo: [String : AnyObject]?, completion: ((Bool, Bool) -> Void)?) {
//super.dispatchEventOfType(type, canBubble: canBubble, cancellable: isCancellable, extraInfo: extraInfo, completion: completion)
}
internal override func dispatchEventWithName(eventName: String, canBubble: Bool, cancellable isCancellable: Bool, extraInfo: [String : AnyObject]?, completion: ((Bool, Bool) -> Void)?) {
//...
}
}
以下是设置自定义接口工厂的方法：
class CustomInterfaceFactory: TVInterfaceFactory {
let kCustomViewTag = 97142 // unlikely to collide
override func viewForElement(element: TVViewElement, existingView: UIView?) -> UIView? {
if (element.elementName == "title") {
if (existingView != nil) {
return existingView
}
let textElement = (element as! TVTextElement)
if (textElement.attributedText!.length > 0) {
let label = UILabel()
// Configure your label here (this is a good way to set a custom font, for example)...
// You can examine textElement.style or textElement.textStyle to get the element's style properties
label.backgroundColor = UIColor.redColor()
let existingText = NSMutableAttributedString(attributedString: textElement.attributedText!)
label.text = existingText.string
return label
}
} else if element.elementName == "loadingIndicator" {
if (existingView != nil && existingView!.tag == kCustomViewTag) {
return existingView
}
let view = UIImageView(image: UIImage(named: "loading.png"))
return view // Simple example. You could easily use your own UIView subclass
}
return nil // Don't call super, return nil when you don't want to override anything...
}
// Use either this or viewForElement for a given element, not both
override func viewControllerForElement(element: TVViewElement, existingViewController: UIViewController?) -> UIViewController? {
if (element.elementName == "whatever") {
let whateverStoryboard = UIStoryboard(name: "Whatever", bundle: nil)
let viewController = whateverStoryboard.instantiateInitialViewController()
return viewController
}
return nil
}
// Use this to return a valid asset URL for resource:// links for badge/img src (not necessary if the referenced file is included in your bundle)
// I believe you could use this to cache online resources (by replacing resource:// with http(s):// if a corresponding file doesn't exist (then starting an async download/save of the resource before returning the modified URL). Just return a file url for the version on disk if you've already cached it.
override func URLForResource(resourceName: String) -> NSURL? {
return nil
}
}
不幸的是，不会为所有元素调用 view/viewControllerForElement:。一些现有的元素（如集合视图）将自己处理其子元素的呈现，而不涉及您的界面工厂，这意味着您必须覆盖更高级别的元素，或者可能使用类别/swizzling 或 UIAppearance 来获取你想要的效果。
最后，正如我刚才所暗示的，您可以使用 UIAppearance 来更改某些内置视图的外观。这是更改 TVML 应用程序标签栏外观的最简单方法，例如：
// in didFinishLaunching...
UITabBar.appearance().backgroundImage = UIImage()
UITabBar.appearance().backgroundColor = UIColor(white: 0.5, alpha: 1.0)
如果你已经有一个适用于 tvOS 的原生 UIKit 应用程序，但想通过使用 TVMLKit 来扩展它，你可以。
将 TVMLKit 用作原生 tvOS 应用程序中的子应用程序。下面的应用程序展示了如何做到这一点，通过保留TVApplicationController和呈现navigationController来自TVApplicationController. TVApplicationControllerContext用于将数据传输到 JavaScript 应用程序，因为 url 在此处传输：
class ViewController: UIViewController, TVApplicationControllerDelegate {
// Retain the applicationController
var appController:TVApplicationController?
static let tvBaseURL = "http://localhost:9001/"
static let tvBootURL = "\(ViewController.tvBaseURL)/application.js"
@IBAction func buttonPressed(_ sender: UIButton) {
print("button")
// Use TVMLKit to handle interface
// Get the JS context and send it the url to use in the JS app
let hostedContContext = TVApplicationControllerContext()
if let url = URL(string: ViewController.tvBootURL) {
hostedContContext.javaScriptApplicationURL = url
}
// Save an instance to a new Sub application, the controller already knows what window we are running so pass nil
appController = TVApplicationController(context: hostedContContext, window: nil, delegate: self)
// Get the navigationController of the Sub App and present it
let navc = appController!.navigationController
present(navc, animated: true, completion: nil)
}
是的。请参阅TVMLKit 框架，其文档以：
TVMLKit 框架使您能够将 JavaScript 和 TVML 文件合并到二进制应用程序中以创建客户端-服务器应用程序。
从这些文档的快速浏览来看，您似乎使用各种TVWhateverFactory类从 TVML 创建 UIKit 视图或视图控制器，之后您可以将它们插入到 UIKit 应用程序中。