A Flutter plugin project to help with App/Deep Links (Android) and Universal Links and Custom URL schemes (iOS).
These links are simply web-browser-like-links that activate your app and may contain information that you can use to load specific section of the app or continue certain user activity from a website (or another app).
App Links and Universal Links are regular https links, thus if the app is not installed (or setup correctly) they'll load in the browser, allowing you to present a web-page for further action, eg. install the app.
Make sure you read both the Installation and the Usage guides, thoroughly, especiallly for App/Universal Links (the https scheme).
To use the plugin, add uni_links as a
dependency in your pubspec.yaml file.
Android and iOS require to declare links' permission in a configuration file.
Feel free to examine tha example app in the example directory for Deep Links (Android) and Custom URL schemes (iOS).
The following steps are not Flutter specific, but platform specific. You might be able to find more in-depth guides elsewhere online, by searching about App Links or Deep Links on Android; Universal Links or Custom URL schemas on iOS.
Uni Links supports two types of Android links: "App Links" and "Deep Links".
- App Links only work with
httpsscheme and require a specified host, plus a hosted file -assetlinks.json. Check the Guide links below. - Deep Links can have any custom scheme and do not require a host, nor a
hosted file. The downside is that any app can claim a scheme + host combo, so
make sure yours are as unique as possible, eg.
HST0000001://host.com.
You need to declare at least one of the two intent filters in android/app/src/main/AndroidManifest.xml:
<manifest ...>
<!-- ... other tags -->
<application ...>
<activity ...>
<!-- ... other tags -->
<!-- Deep Links -->
<intent-filter>
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.BROWSABLE" />
<!-- Accepts URIs that begin with YOUR_SCHEME://YOUR_HOST -->
<data
android:scheme="[YOUR_SCHEME]"
android:host="[YOUR_HOST]" />
</intent-filter>
<!-- App Links -->
<intent-filter android:autoVerify="true">
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.BROWSABLE" />
<!-- Accepts URIs that begin with https://YOUR_HOST -->
<data
android:scheme="https"
android:host="[YOUR_HOST]" />
</intent-filter>
</activity>
</application>
</manifest>The android:host attribute is optional for Deep Links.
To further the specificity you can add an android:pathPrefix attribute:
<!-- Accepts URIs that begin with YOUR_SCHEME://YOUR_HOST/NAME/NAME... -->
<!-- Accepts URIs that begin with https://YOUR_HOST/NAME/NAME... -->
<!-- note that the leading "/" is required for pathPrefix -->
<data
android:scheme="[YOUR_SCHEME_OR_HTTPS]"
android:host="[YOUR_HOST]"
android:pathPrefix="/[NAME][/NAME...]" />For more info read
The Ultimate Guide.
Pay close attention to the
App Links
section in the Guide regarding the required /.well-known/assetlinks.json
file.
The Android developer docs are also a great source of information for both Deep Links and App Links.
There are two kinds of links in iOS: "Universal Links" and "Custom URL schemes".
- Universal Links only work with
httpsscheme and require a specified host, entitlements and a hosted file -apple-app-site-association. Check the Guide links below. - Custom URL schemes can have... any custom scheme and there is no host
specificity, nor entitlements or a hosted file. The downside is that any app
can claim any scheme, so make sure yours is as unique as possible,
eg.
hst0000001ormyIncrediblyAwesomeScheme.
You need to declare at least one of the two.
--
For Universal Links you need to add or create a
com.apple.developer.associated-domains entitlement - either through Xcode or
by editing (or creating and adding to Xcode) ios/Runner/Runner.entitlements
file.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<!-- ... other keys -->
<key>com.apple.developer.associated-domains</key>
<array>
<string>applinks:[YOUR_HOST]</string>
</array>
<!-- ... other keys -->
</dict>
</plist>This allows for your app to be started from https://YOUR_HOST links.
For more information, read Apple's guide for Universal Links.
--
For Custom URL schemes you need to declare the scheme in
ios/Runner/Info.plist (or through Xcode's Target Info editor,
under URL Types):
<?xml ...>
<!-- ... other tags -->
<plist>
<dict>
<!-- ... other tags -->
<key>CFBundleURLTypes</key>
<array>
<dict>
<key>CFBundleTypeRole</key>
<string>Editor</string>
<key>CFBundleURLName</key>
<string>[ANY_URL_NAME]</string>
<key>CFBundleURLSchemes</key>
<array>
<string>[YOUR_SCHEME]</string>
</array>
</dict>
</array>
<!-- ... other tags -->
</dict>
</plist>This allows for your app to be started from YOUR_SCHEME://ANYTHING links.
For a little more information, read Apple's guide for Inter-App Communication.
I strongly recommend watching the Apple WWDC 2015, session 509 - Seamless Linking to Your App to understand how the Universal Links work (and are setup).
There are two ways your app will recieve a link - from cold start and brought from the background. More on these after the example usage in More about app start from a link.
Returns the link that the app was started with, if any.
import 'dart:async';
import 'dart:io';
import 'package:uni_links/uni_links.dart';
import 'package:flutter/services.dart' show PlatformException;
// ...
Future<Null> initUniLinks() async {
// Platform messages may fail, so we use a try/catch PlatformException.
try {
String initialLink = await getInitialLink();
// Parse the link and warn the user, if it is not correct,
// but keep in mind it could be `null`.
} on PlatformException {
// Handle exception by warning the user their action did not succeed
// return?
}
}
// ...Same as the getInitialLink, but converted to a Uri.
// Uri parsing may fail, so we use a try/catch FormatException.
try {
Uri initialUri = await getInitialUri();
// Use the uri and warn the user, if it is not correct,
// but keep in mind it could be `null`.
} on FormatException {
// Handle exception by warning the user their action did not succeed
// return?
}
// ... other exception handling like PlatformExceptionOne can achieve the same by using Uri.parse(initialLink), which is what this
convenience method does.
Usually you would check the getInitialLink and also listen for changes.
import 'dart:async';
import 'dart:io';
import 'package:uni_links/uni_links.dart';
// ...
StreamSubscription _sub;
Future<Null> initUniLinks() async {
// ... check initialLink
// Attach a listener to the stream
_sub = getLinksStream().listen((String link) {
// Parse the link and warn the user, if it is not correct
}, onError: (err) {
// Handle exception by warning the user their action did not succeed
});
// NOTE: Don't forget to call _sub.cancel() in dispose()
}
// ...Same as the stream, but transformed to emit Uri objects.
Usually you would check the getInitialUri and also listen for changes.
import 'dart:async';
import 'dart:io';
import 'package:uni_links/uni_links.dart';
// ...
StreamSubscription _sub;
Future<Null> initUniLinks() async {
// ... check initialUri
// Attach a listener to the stream
_sub = getUriLinksStream().listen((Uri uri) {
// Use the uri and warn the user, if it is not correct
}, onError: (err) {
// Handle exception by warning the user their action did not succeed
});
// NOTE: Don't forget to call _sub.cancel() in dispose()
}
// ...If the app was terminated (or rather not running in the background) and the OS
must start it anew - that's a cold start. In that case, getInitialLink will
have the link that started your app and the Stream won't produce a link (at
that point in time).
Alternatively - if the app was running in the background and the OS must bring
it to the foreground the Stream will be the one to produce the link, while
getInitialLink will be either null, or the initial link, with which the
app was started.
Because of these two situations - you should always add a check for the initial link (or URI) and also subscribe for a Stream of links (or URIs).
If you register a schema, say unilink, you could use these cli tools:
You could do below tasks within Android Studio.
Assuming you've installed Android Studio (with the SDK platform tools):
adb shell 'am start -W -a android.intent.action.VIEW -c android.intent.category.BROWSABLE -d "unilinks://host/path/subpath"'
adb shell 'am start -W -a android.intent.action.VIEW -c android.intent.category.BROWSABLE -d "unilinks://example.com/path/portion/?uid=123&token=abc"'
adb shell 'am start -W -a android.intent.action.VIEW -c android.intent.category.BROWSABLE -d "unilinks://example.com/?arr%5b%5d=123&arr%5b%5d=abc&addr=1%20Nowhere%20Rd&addr=Rand%20City%F0%9F%98%82"'If you don't have adb
in your path, but have $ANDROID_HOME env variable then use
"$ANDROID_HOME"/platform-tools/adb ....
Note: Alternatively you could simply enter an adb shell and run the
am commands in it.
Note: I use single quotes, because what follows the shell command is what will
run in the emulator (or device) and shell metacharacters, such as question marks
(?) and ampersands (&), usually mean something different to your own shell.
adb shell communicates with the only available device (or emulator), so if
you've got multiple devices you have to specify which one you want to run the
shell in via:
- The only USB connected device -
adb -d shell '...' - The only emulated device -
adb -e shell '...'
You could use adb devices to list currently available devices (similarly
flutter devices does the same job).
Assuming you've got Xcode already installed:
/usr/bin/xcrun simctl openurl booted "unilinks://host/path/subpath"
/usr/bin/xcrun simctl openurl booted "unilinks://example.com/path/portion/?uid=123&token=abc"
/usr/bin/xcrun simctl openurl booted "unilinks://example.com/?arr%5b%5d=123&arr%5b%5d=abc&addr=1%20Nowhere%20Rd&addr=Rand%20City%F0%9F%98%82"If you've got xcrun (or simctl) in your path, you could invoke it directly.
The flag booted assumes an open simulator (you can start it via
open -a Simulator) with a booted device. You could target specific device by
specifying its UUID (found via xcrun simctl list or flutter devices),
replacing the booted flag.
These types of links use https for schema, thus you can use above examples by
replacing unilinks with https.
For help on editing plugin code, view the documentation.
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