# 4. Usage

{% hint style="danger" %}
This document refers to deprecated parts of the platform and has been left intact to help customers with legacy integrations. In order to access the latest platform features and documentation, please go to <https://docs.sentiance.com>.
{% endhint %}

You can use the SDK calls in your App code in both Swift and Objective-C. If your app is written in Swift, You will need to add a bridging header (if you don't have one already in your project).

Import SENTSDK public header in your bridging header file to access the SDK:

```objectivec
@import SENTSDK;
```

You will also need to setup Location Authorization Permission before initializing the SDK. The Sentiance SDK does not handle location authorizations but needs it to function. Add the necessary code in your app following the [Apple guidelines](https://developer.apple.com/documentation/corelocation/requesting_authorization_for_location_services) for Location Services Authorizations before initializing the SDK.

In the `didFinishLaunchingWithOptions` method of your `AppDelegate`, create a [`SENTConfig`](https://legacy-docs.sentiance.com/sdk/api-reference/ios/sentconfig-1) object with your Sentiance app ID and secret.

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

```
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    let config = SENTConfig(appId: self.appId,            // Add yours.
                            secret: self.secret,          // Add yours.
                            launchOptions: launchOptions)
}
```

{% endtab %}

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

```objectivec
@import SENTSDK;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    SENTConfig *conf = [[SENTConfig alloc] initWithAppId:@"APPID"
                                           secret:@"SECRET"
                                           link:userLinker
                                           launchOptions:launchOptions];
}
```

{% endtab %}
{% endtabs %}

If you don't have an appID and secret key yet, read [these instructions](https://legacy-docs.sentiance.com/sdk/getting-started/..#create-an-application).

{% hint style="danger" %}
In the above example, we hard-code the the appID and secret key for testing purposes. However, this is not secure and can lead to leaked credentials. In your own app, load these credentials from a secure source such a remote server, and store them securely on the device.
{% endhint %}

`SENTConfig` accepts a `userLinker` which is responsible for handling [user linking](https://legacy-docs.sentiance.com/important-topics/user-linking-2.0). The linker is invoked by the SDK when creating a Sentiance user (during the first initialization) to give you a chance to link your app's user to the Sentiance user. If linking succeeds, this linker does not get invoked during subsequent SDK intializations, unless [the SDK gets reset](https://legacy-docs.sentiance.com/api-reference/ios/sentsdk#reset-failure).

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

```objectivec
MetaUserLinker userLinker = ^(NSString *installId, void (^linkSuccess)(void), void (^linkFailed)(void)) {
    // Supply the 'installId' to your server, which should then initiate
    // a user linking request with the Sentiance backend.
    
    [self requestLinking:installId completion:^(BOOL success) {
        if (success) {
            linkSuccess(); // Call if linking succeeds
        } else {
            linkFailed();  // Call if linking fails
        }
    }];
};
```

{% endtab %}
{% endtabs %}

You can learn more about user linking [here](https://legacy-docs.sentiance.com/important-topics/user-linking-2.0).

## Optional: SDK Status update handler

This step is optional, but indispensable if you want to be kept up-to-date with changes to the [SDK status](https://legacy-docs.sentiance.com/sdk/api-reference/ios/sentsdk/sentsdkstatus).

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

```
config.didReceiveSdkStatusUpdate = { status in
}
```

{% endtab %}

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

```
[conf setDidReceiveSdkStatusUpdate:^(SENTSDKStatus *status) {
}];
```

{% endtab %}
{% endtabs %}

## Initializing the SDK

{% hint style="info" %}
Until the SDK is properly initialized, none of the methods in the SDK will work, with the exception of `sharedInstance`, `initWithConfig` and `getInitState.`
{% endhint %}

In the project's `AppDelegate` file,

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

```
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Setup Config.
    let config = SENTConfig(appId: self.appId,            // Add yours.
                            secret: self.secret,          // Add yours.
                            link: userLinker              // If user linking.
                            launchOptions: launchOptions)
                            
    // Initialize SDK.
    SENTSDK.sharedInstance().initWith(config,
                                      success: { // Successful Initialization
                                                 // Add code to start service.
                                                    self.startService()
                                      },
                                      failure: { issue in
                                                    print("Failed to Initialize SDK with issue: \(issue)") 
                                      })
}
```

{% endtab %}

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

```objectivec
@import SENTSDK;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Creation of SENTConfig here, see previous step
   SENTConfig *conf = [[SENTConfig alloc] initWithAppId:@"APPID"
                                           secret:@"SECRET"
                                           link:userLinker
                                           launchOptions:launchOptions];
   
   // Initialize SDK
    [[SENTSDK sharedInstance] initWithConfig:conf success:^{

    } failure:^(SENTInitIssue issue) {

    }];

    return YES;
}
```

{% endtab %}
{% endtabs %}

1. In the `didFinishLaunchingWithOptions` method of your `AppDelegate`, pass the [`SENTConfig`](https://legacy-docs.sentiance.com/sdk/api-reference/ios/sentconfig-1) you created in the previous step to the `initWithConfig` method of the Sentiance SDK.
2. Additionally, [`success`](https://legacy-docs.sentiance.com/api-reference/ios/sentsdk#initwithconfig-success-failure) and [`failure`](https://legacy-docs.sentiance.com/api-reference/ios/sentsdk#initwithconfig-success-failure) blocks must be passed as well, which will inform you when initialization has succeeded or failed.

{% hint style="warning" %}
The [`initWithConfig:`](https://legacy-docs.sentiance.com/api-reference/ios/sentsdk#initwithconfig-success-failure)call must be executed before `didFinishLaunchingWithOptions:` returns. Therefore, you must call it synchronously on the main UI thread. If you plan to add a remote flag to control the initialization (e.g. Firebase Remote Config), make sure the check is synchronous (e.g. using a cached flag).

See [here](https://legacy-docs.sentiance.com/appendix/sdk-initialization#why-initialize-in-the-application-appdelegate-class) to understand more about why this is important.
{% endhint %}

## Starting Detections

We recommend that SDK startup is done within `didFinishLaunchingWithOptions` of `AppDelegate` file to ensure that there are no unintended side effects.

Call the `start` method from the `success` block of the [`initWithConfig`](https://legacy-docs.sentiance.com/api-reference/ios/sentsdk#initwithconfig-success-failure) method:

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

```
SENTSDK.sharedInstance().start { status in
    if let status = status {
        switch status.startStatus {
        case SENTStartStatus.notStarted:
            print("SDK Status: Not started")
        case SENTStartStatus.pending:
            print("SDK Status: Pending")
        case SENTStartStatus.started:
            print("SDK Status: Started")
        case SENTStartStatus.expired:
            print("SDK Status: Expired")
        @unknown default:
            print("Status unknown")
        }
    }
}
```

{% endtab %}

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

```objectivec
[[SENTSDK sharedInstance] start:^(SENTSDKStatus *status) {
    if ([status startStatus] == SENTStartStatusStarted) {
        // SDK started properly.
    } else if ([status startStatus] == SENTStartStatusPending) {
        // Something prevented the SDK to start properly (check the location permission). Once fixed, the SDK will start automatically.
    } else {
        // SDK did not start.
    }
}];
```

{% endtab %}
{% endtabs %}

You can check the `status` to see whether starting has succeeded correctly or not.

## Overall Code

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

```
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Handle Location permissions before-hand.
        
        // Setup Config.
        let config = SENTConfig(appId: "",          // Add yours.
                                secret: "",         // Add yours.
                                link: userLinker    // If user linking.
                                launchOptions: launchOptions)
        
        // Initialize SDK.
        SENTSDK.sharedInstance().initWith(config,
            success: {
              // Start the SDK
              SENTSDK.sharedInstance().start { status in
                  // Handle the start status.
              }
            },
            failure: { issue in
              print("Failed to Initialize the SDK due to issue: \(issue)")
            })
        return true
    }
```

{% endtab %}

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

```objectivec
@import SENTSDK;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Creation of SENTConfig here, see previous step
   SENTConfig *conf = [[SENTConfig alloc] initWithAppId:@"APPID"
                                           secret:@"SECRET"
                                           link:userLinker
                                           launchOptions:launchOptions];
   
   // Initialize SDK
    [[SENTSDK sharedInstance] initWithConfig:conf success:^{

        // SDK Start
       [[SENTSDK sharedInstance] start:^(SENTSDKStatus *status) {
            if ([status startStatus] == SENTStartStatusStarted) {
                // SDK started properly.
            } else if ([status startStatus] == SENTStartStatusPending) {
                // Something prevented the SDK to start properly (check the location permission). Once fixed, the SDK will start automatically.
            } else {
            // SDK did not start.
            }
        }];

    } failure:^(SENTInitIssue issue) {

    }];

    return YES;
}
```

{% endtab %}
{% endtabs %}