必要 (
Android MediaRouter 的預設行為)：
A 傳送端應用程式未連線至 Cast 接收器時，輕觸 Cast 按鈕會顯示 Cast 對話方塊
B Cast 對話方塊會顯示「投放到」標題
C Cast 對話方塊會顯示可用 Web 接收器清單
D 目前正在投放的每個接收器都會顯示「正在投放『應用程式名稱』」
如果是 iOS 裝置，使用者必須先同意允許投放裝置存取區域網路 (LNA)，才能首次投放內容。系統會向使用者顯示插頁式資訊畫面，說明為何需要這項權限，接著顯示標準的 Apple LNA 權限對話方塊。
首次投放後，如果使用者透過 Wi-Fi 輕觸「投放」按鈕時，系統找不到任何裝置，就會顯示說明畫面，解釋 Web Receiver 可能無法使用的原因 (例如停用區域網路存取權，或 Wi-Fi 網路發生問題)。
必要：
A 首次投放：首次輕觸「投放」按鈕後，系統必須顯示插頁式廣告，向使用者說明為何應允許應用程式存取區域網路裝置。插頁式廣告應包含需要存取本機網路的原因，以提高使用者接受本機權限存取要求的可能性。 B 無法使用接收器：輕觸「投放」按鈕會顯示說明畫面，說明使用者無法探索 Web 接收器的可能原因，並提供「設定」連結，修正 LNA 權限問題。
[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["缺少我需要的資訊","missingTheInformationINeed","thumb-down"],["過於複雜/步驟過多","tooComplicatedTooManySteps","thumb-down"],["過時","outOfDate","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["示例/程式碼問題","samplesCodeIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-09-04 (世界標準時間)。"],[[["\u003cp\u003eThe Cast dialog enables users to connect to, manage, and disconnect from Web Receivers and should be implemented consistently across platforms.\u003c/p\u003e\n"],["\u003cp\u003eOn iOS, users must grant local network access permission for initial casting and may encounter a help screen if no devices are found.\u003c/p\u003e\n"],["\u003cp\u003eWhen connected, the Cast dialog displays the receiver name and a "STOP CASTING" button, offering controls for the casting session.\u003c/p\u003e\n"],["\u003cp\u003eFor optimal user experience, it's recommended to include persistent controls alongside those within the Cast dialog, enhancing user interaction.\u003c/p\u003e\n"],["\u003cp\u003eAndroid apps can leverage the MediaRouter component for built-in Cast dialog UX, simplifying implementation.\u003c/p\u003e\n"]]],[],null,["# Cast Dialog\n\nThe Cast dialog is shown whenever the Cast button is pressed. The Cast dialog lets users\nconnect, control, and disconnect from Web Receivers.\n| **Note:** For Android apps, use the `MediaRouter` component from the MediaRouter Support Library to implement the Cast dialog. It has all of the UX requirements built right in.\n| **Note:** For iOS senders, a special Local Network Access interstitial dialog must be displayed the first time a user attempts to cast.\n\nIf you're developing a custom implementation or building an app for iOS or Chrome, you must\nimplement this dialog in a consistent way, so that users recognize and trust it to function\nconsistently across devices, apps and platforms. Refer to the\n[Reference apps](/cast/docs/sample_apps#reference_apps) for examples.\n\n### [Cast dialog, not connected (receivers available)](#sender-cast-menu-available)\n\n\n**Required** (default behavior of [Android MediaRouter](https://developer.android.com/reference/androidx/mediarouter/media/MediaRouter)):\n\n\nA When the sender app is not connected to a Cast receiver,\ntapping the Cast button shows the Cast dialog\n\n\nB The Cast dialog title, \"Cast to\" appears\n\n\nC The Cast dialog shows a list of available Web Receivers\n\n\nD Each receiver currently casting should display, \"Casting\n*app name*\"\n\n**Note the multi-user scenarios:**\n\n- When another user connects to a receiver currently casting from the same app and account, the sender app provides the controls for the cast content.\n- When another user connects to a receiver currently casting from an app that is not casting, the previous sender app disconnects and the new sender app connects.\n\n### Android\n\nCast dialog, not connected \nCast home screen \n\n### iOS\n\nCast dialog, not connected \nCast home screen \n\n### Chrome\n\nCast dialog, not connected \nCast home screen \n\n### [Cast dialog, not connected (iOS only)](#sender-cast-menu-available)\n\n\nFor iOS, when casting for the first time, users must consent to allow local network access (LNA) to\nCast devices. An interstitial information screen is presented\nto users explaining why this permission is needed, followed by the standard Apple LNA\npermissions dialog.\n\n\nAfter casting for the first time, if no devices are found when the Cast button is tapped while the\nuser is on Wi-Fi, a help screen is presented\nexplaining why Web Receivers might not be available (for example,\nlocal network access is disabled, or there is a problem with the Wi-Fi network).\n\n\n**Required** :\n\n\nA First-time casting: After tapping on the Cast button\nfor the first time,\nan Interstitial must be shown to explain to the user why they should allow\nthe app to access local network devices. The interstitial should include information on\nwhy local network access is needed, to increase the likelihood of the user accepting\nlocal permission access.\n\n\nB Receivers unavailable: Tapping the Cast button\ndisplays a help screen explaining possible reasons the user\nis unable to discover Web Receivers, along with links to Settings to fix LNA permissions issues. \n\n### First-time casting (iOS)\n\nFirst-time casting: interstitial and local network access permissions \n\n### Receivers unavailable\n\nReceivers unavailable \n\n### [Cast dialog, connected but not casting](#sender-cast-menu-connected)\n\n\n**Required**\n\n\nA When the sender app is connected to a Web Receiver,\ntapping the Cast button shows the Cast dialog\n\n\nB The Cast dialog title \"Receiver-Name\" appears\n\n\nC The Cast dialog shows a button to stop casting\nwith button label \"STOP CASTING\" (for more information about disconnecting, see\n[Sender stops cast](/cast/docs/design_checklist/sender#sender-control-end)) \n\n### Android\n\nCast dialog, connected but not casting \nReceiver app loaded / idle \n\n### iOS\n\nCast dialog, connected but not casting \nReceiver app loaded / idle \n\n### [Cast dialog, while casting](#sender-cast-menu-casting)\n\n\n**Required**\n\n\nA The Cast dialog title \"Receiver-Name\" appears\n\n\nB The receiver or content currently casting is shown below\nthe title\n\n\nC The Cast dialog shows a \"STOP CASTING\" button that stops\ncasting (for more information see\n[Sender stops cast](/cast/docs/design_checklist/sender#sender-control-end))\n\n**Best practice**\n\n- For the best user experience, provide [persistent controls](/cast/docs/design_checklist/sender#sender-mini-controller) in addition to the controls in the Cast dialog.\n\n### Android\n\nCast dialog, while casting \nReceiver playing content \n\n### iOS\n\nCast dialog, while casting \nReceiver playing content \n\n### Chrome\n\nCast dialog, while casting \nReceiver playing content \n\n**Images used in this design guide**\nare courtesy of the Blender Foundation, shared under copyright or Creative Commons license.\n\n- Elephant's Dream: (c) copyright 2006, Blender Foundation / Netherlands Media Art Institute / www.elephantsdream.org\n- Sintel: (c) copyright Blender Foundation \\| www.sintel.org\n- Tears of Steel: (CC) Blender Foundation \\| mango.blender.org\n- Big Buck Bunny: (c) copyright 2008, Blender Foundation / www.bigbuckbunny.org"]]
