# Fast App Switch



**Warning:** These Facebook Login features are part of an open beta. If you encounter any issues, please use our [feedback form](https://docs.google.com/forms/d/1bLzUXulQAtPRbFR0efDvLUZvIqSA90eYKPYKdfIA5X8/).

**Fast App Switch** logs people in by switching to the native Facebook app on iOS rather than routing through an in-app browser. Because they are already authenticated inside the Facebook app, the flow is faster and more familiar, and it avoids the browser cookie problems that cause avoidable re-authentication.

The SDK opens `fbauth2://authorize` directly against the Facebook app. When the Facebook app is not installed, login falls back to the browser-based flow automatically, so the call always completes.

**Note:** Fast App Switch applies to **classic Facebook Login only**. Limited Login attempts, including shimmed Limited Login, continue to use the browser flow.

## Requirements {#requirements}

| Requirement | Notes |
|---|---|
| Facebook SDK for iOS | **18.1.1 or later.** Use the latest release. |
| `LSApplicationQueriesSchemes` | Your app's `Info.plist` must list `fbauth2` so the SDK can deep link into the native Facebook Login flow. |
| Facebook app | Installed and signed in. Without it, login falls back to the browser flow. |
| Login type | Classic Facebook Login. Not available for Limited Login. |

## Set up {#setup}

Add `fbauth2` to `LSApplicationQueriesSchemes` in your `Info.plist`. If you already declare schemes for other Facebook features, add `fbauth2` to the existing array rather than creating a second one:

```
<key>LSApplicationQueriesSchemes</key>
<array>
  <string>fbauth2</string>
  <string>fbapi</string>
  <string>fb-messenger-share-api</string>
</array>
```

That is the only required change. Once you are on a supported SDK version with the scheme declared, eligible logins app-switch automatically.

**Note:** **Note for apps upgrading from 18.0.2 or earlier:** Fast App Switch was opt-in in 18.0.2 and is on by default from 18.0.3 onward. If your app declares `fbauth2` and does not set `appSwitch` explicitly, eligible logins will begin switching to the Facebook app after you upgrade, with no code change on your part. Set `appSwitch: .disabled` to keep the previous browser-based behavior.

## Control the behavior {#control}

Fast App Switch is controlled by the `appSwitch` property, which takes `AppSwitch.enabled` or `AppSwitch.disabled`.

**`appSwitch` defaults to `.enabled`.** You do not need to opt in — declare the scheme and eligible logins use the Facebook app. Set `.disabled` only when you specifically want to force the browser-based flow.

### On a login attempt {#login-configuration}

Set `appSwitch` on the `LoginConfiguration` to control a single login attempt:

### Swift
```
// Explicitly enable (this is already the default).
let loginConfiguration = LoginConfiguration(
    permissions: permissions,
    tracking: tracking,
    appSwitch: .enabled
)

// Force the browser-based flow instead.
let browserOnly = LoginConfiguration(
    permissions: permissions,
    tracking: tracking,
    appSwitch: .disabled
)
```

### Objective-C
```
FBSDKLoginConfiguration *configuration =
  [[FBSDKLoginConfiguration alloc] initWithPermissions:permissions
                                              tracking:tracking
                                             appSwitch:FBSDKAppSwitchEnabled];
```

### On the login button {#login-button}

Set `appSwitch` on an `FBLoginButton` to control logins performed through the button:

### Swift
```
let loginButton = FBLoginButton()
loginButton.appSwitch = .enabled
```

### Objective-C
```
FBSDKLoginButton *loginButton = [FBSDKLoginButton new];
loginButton.appSwitch = FBSDKAppSwitchEnabled;
```

## Unity {#unity}

The Facebook SDK for Unity exposes this as `FB.Mobile.SetFastAppSwitchEnabled`, which is **iOS-only** and a no-op on Android.

Call it after `FB.Init()` and **before** the login call. It affects the initial login attempt made through `LoginWithTrackingPreference`:

```
FB.Mobile.SetFastAppSwitchEnabled(true);
```

As on native iOS, the Unity bridge defaults to Fast App Switch being on, so you only need this call to turn it **off**:

```
FB.Mobile.SetFastAppSwitchEnabled(false);
```

## Troubleshooting {#troubleshooting}

* **Login stays in the browser.** Check that `fbauth2` is in `LSApplicationQueriesSchemes` — without it the SDK cannot detect the Facebook app. Also confirm the Facebook app is installed and signed in, and that the attempt is a classic Login rather than a Limited Login.
* **Limited Login never app-switches.** That is expected. Fast App Switch is for classic Login only.
* **Nothing changes after upgrading.** Confirm you are on 18.1.1 or later and that nothing in your code sets `appSwitch: .disabled` on the `LoginConfiguration` or the login button.
* **Inspect logs.** Attach the device and filter the system console to the subsystem `com.facebook.sdk`.

## See Also

* [Facebook Login for iOS](https://developers.facebook.com/documentation/facebook-login/ios)
* [Facebook Login for iOS - Advanced](https://developers.facebook.com/documentation/facebook-login/ios/advanced)
* [Permissions with Facebook Login](https://developers.facebook.com/documentation/facebook-login/ios/permissions)
* [Limited Login](https://developers.facebook.com/documentation/facebook-login/ios/limited-login)
* [Limited Login Data Refresh](https://developers.facebook.com/documentation/facebook-login/ios/limited-login/data-refresh)