# Start the SDK

The `start` must be done **as soon as possible** to catch every purchase / renewal.\
On iOS, initialise the SDK in your `AppDelegate` method `didFinishLaunchingWithOptions` to allow promoted In-App Purchase and support PSD2.\
This initialisation will allow tyou to access products prices instantly later in the app. 

{% hint style="info" %}
You will need an API Key that you can find in your App settings in the [Purchasely Console](https://purchasely.io). 
{% endhint %}

<figure><img src="/files/8zld3a5e7efVTzxTT2uC" alt=""><figcaption></figcaption></figure>

{% tabs %}
{% tab title="Swift" %}

```swift
import Purchasely

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    Purchasely.start(withAPIKey: "API_KEY", appUserId: "USER_ID")
	return true
}
```

{% endtab %}

{% tab title="Objective-C" %}

```objectivec
#import <Purchasely/Purchasely-Swift.h>

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
	// Override point for customization after application launch.

	[Purchasely startWithAPIKey:@"API_KEY"
			  appUserId:@"USER_ID"
			runningMode: PLYRunningModeFull
	              eventDelegate:nil
			 uiDelegate:nil
	  paywallActionsInterceptor:nil
		           logLevel: LogLevelInfo
			initialized: nil];
	return YES;
}
```

{% endtab %}

{% tab title="Kotlin" %}

```kotlin
import io.purchasely.ext.Purchasely

Purchasely.Builder(applicationContext)
    .apiKey("API_KEY")
    .logLevel(LogLevel.DEBUG) // set to warning or error for release
    .userId("USER_ID")
    .eventListener(eventListener)
    .runningMode(PLYRunningMode.Full)
    .stores(listOf(GoogleStore(), HuaweiStore()))
    .build()

// When you are ready for Purchasely to initialize,
// you must call start() method that will grab configuration and products
// from the selected stores.
Purchasely.start { isConfigured ->
}
```

{% endtab %}

{% tab title="Java" %}

```java
List<Store> stores = new ArrayList();
stores.add(new GoogleStore(), new HuaweiStore());

new Purchasely.Builder(getApplicationContext())
    .apiKey("API_KEY")
    .logLevel(LogLevel.DEBUG) // set to warning or error for release
    .userId("USER_ID")
    .eventListener(this)
    .runningMode(PLYRunningMode.Full.INSTANCE)
    .stores(stores)
    .build();

// When you are ready for Purchasely to initialize,
// you must call start() method that will grab configuration and products
// from the selected stores.
Purchasely.start(isConfigured -> {
    null;
});
```

{% endtab %}

{% tab title="React Native" %}

```javascript
import Purchasely from 'react-native-purchasely';

/**
* @params String apiKey
* @params StringArray stores : may be Google, Amazon and Huawei
* @params String userId
* @params Purchasley.LogLevel logLevel
* @params RunningMode runningMode
**/
Purchasely.startWithAPIKey(
  'API_KEY',
  ['Google'],
  'USER_ID',
  Purchasely.logLevelDebug,
  RunningMode.FULL
);

```

{% endtab %}

{% tab title="Cordova" %}

```javascript
/**
* @params String apiKey
* @params StringArray stores : may be Google, Amazon and Huawei
* @params String userId
* @params Purchasley.LogLevel logLevel
* @params Purchasely.RunningMode runningMode
**/
Purchasely.startWithAPIKey(
    'API_KEY', 
    ['Google'], 
    null, 
    Purchasely.LogLevel.DEBUG, 
    Purchasely.RunningMode.full
);
```

{% endtab %}

{% tab title="Flutter" %}

```dart
/**
* @params String apiKey
* @params StringArray stores : may be Google, Amazon and Huawei
* @params String userId
* @params PLYLogLevel logLevel
* @params PLYRunningMode runningMode
**/
bool configured = await Purchasely.startWithApiKey(
        'API_KEY',
        ['Google'],
        null,
        PLYLogLevel.debug,
        PLYRunningMode.full
    );
    
if (!configured) {
        print('Purchasely SDK not configured');
        return;
}
```

{% endtab %}

{% tab title="Unity" %}

```csharp
...
private PurchaselyRuntime.Purchasely _purchasely;

_purchasely = new PurchaselyRuntime.Purchasely("userId",
			false,
			LogLevel.Debug,
			RunningMode.Full,
			OnPurchaselyStart,
			OnPurchaselyEvent);
```

{% endtab %}
{% endtabs %}

The `userID` parameter is optional and allows you to associate the purchase to a user instead of a device.

The `eventDelegate`/`eventListener` parameter is optional and allows you to listen to all purchases events. You should implement it at least to know when the purchase is successfull.

The `uiDelegate` / `uiListener` parameter is optional and allows you to override UI dialog presented to user in case of error or success.

The `logLevel` parameter is optional and will display logs from the SDK according to the level set. We advise you to set it to warning or error for production

The `stores` parameter (for Android apps) is optional but purchase won't work without it. You need to pass a list of stores that are enabled for your application. The first store available in the user device will be the store used to make a purchase. In this sample, Google Play Billing will be used if available in user device, Huawei Mobile Services will be used otherwise.

The `runningMode` parameter is optional and allows you to use Purchasely with another In-App purchase system to prepare a migration. More details in our dedicated [section](/purchasely/3.4/quick-start-1/sdk-configuration.md).


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://purchasely.gitbook.io/purchasely/3.4/quick-start-1/sdk-configuration/config-appendices/start-the-sdk.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.