i. Download the iPay SDK for Android

ii. Import the iPay SDK

To use the iPay SDK in a project, simply add the dependency to your build.gradle or you can download and add Android Archive Library(AAR) file to your libs folder.

Important: If you're adding the SDK to an existing project, start at step 3.

Install via Central Dependency

Go to Android Studio, | New Project | Minimum SDK.
Select API 16: Android 4.1 ( Jelly Bean ) or higher and create your new project.
In your project, open your_app_module | Gradle Scripts | build.gradle (Project) and add the following line to the dependencies{ } section.
```
implementation "bd.com.ipay.sdk:sdk-android:1.0.5"
```
If your project using kotlin and development language then add the following line to the dependencies{ } section.
```
implementation "bd.com.ipay.sdk:sdk-android-ktx:1.0.5"
```
Build your project.

Install via Downloaded AAR file

Go to Android Studio, | New Project | Minimum SDK.
Select API 16: Android 4.1 ( Jelly Bean ) or higher and create your new project.
Go to Project Root Folder | app. create a new folder, rename it to libs.
In your project, open your_app_module | Gradle Scripts | build.gradle (Project) and add the following line to the dependencies{ } section.
```
implementation fileTree(include: ['*.jar', '*.aar'], dir: 'libs')
```
Build your project.

Important: If your project compile SDK version is below 28 then add the following lines

configurations.all {
    resolutionStrategy {
        force "com.android.support:support-compat:$targetSupportLibraryVersion"
        force "com.android.support:support-annotations:$targetSupportLibraryVersion"
    }
}

iii. Edit Your Resources and Manifest

Create strings for your callback url scheme and for those needed to receive checkout status result in a New Activity add the CallbackActivityName to your AndroidManifest.xml. Also you can enable/disable SDK initialize logs.

Important: Create a callback url scheme from iPay app. Please contact with us in order to create this url scheme.

Open your /app/res/values/strings.xml file.

Add the following:

    <string name="ipay_callback_url_scheme" translatable="false">YOUR_CALLBACK_CODE_FROM_IPAY_APP</string>

Open the /app/manifest/AndroidManifest.xml file.

Add the following meta-data elements:

 <application>
     <!-- Optional metadata field. If you want to get callback to a new activity,
         then add the following like where the value will be the name of the callback activity 
         you want to open.-->
     <meta-data
         android:name="bd.com.ipay.sdk.CallbackActivityName"
         android:value="bd.com.ipay.activity.IPayCheckoutCallBackActivity" />
     <!-- Optional metadata field. If you don't want to print anything in the log, 
          use false as value.-->
     <meta-data
         android:name="com.facebook.sdk.AutoLogAppEventsEnabled"
         android:value="true" />
     <!-- Optional metadata field. update the value field by your own choice. 
          Use this value to receive request result from onActivityResult-->
     <meta-data
         android:name="bd.com.ipay.sdk.CallbackRequestCode"
         android:value="1234" />
 </application>

iv. Add checkout code snippet

Follow the iPay Payment Gateway API guide for merchants(Version 1.2.1) to create an paymentUrl. Use this paymentUrl to perform checkout through your android application.

The simplest way to perform iPay checkout through iPay Android app from your app is to add the following lines of code.

// sample java checkout code.
public void iPayCheckoutPayment(Activity activity, String paymentUrl) {
    final CheckoutState checkoutState = IPaySDK.performCheckout(activity, paymentUrl);
}

 // sample kotlin checkout code.
 fun iPayCheckoutPayment(paymentUrl : String) {
    val checkoutState = performCheckout(paymentUrl)  
 }

In case of iPay android isn’t present, it will open play store to download the iPay app. Also you will the checkout result on onActivityResult

If you are willing to receive result in a new activity, use the following lines of code.

// sample java checkout code.
private final boolean SHOULD_THROW_ERROR_WHILE_PERFORMING_CHECKOUT = true;
private final boolean SHOULD_RECEIVE_RESULT_ON_NEW_ACTIVITY = true;
public void iPayCheckoutPayment(Activity activity, String paymentUrl) {
    try {
        final CheckoutState checkoutState = IPaySDK.performCheckout(activity, paymentUrl, SHOULD_THROW_ERROR_WHILE_PERFORMING_CHECKOUT,SHOULD_RECEIVE_RESULT_ON_NEW_ACTIVITY);
    } catch(Exception e) {
        // perform checkout failed exceptions
    }
}

// sample kotlin checkout code.
const val SHOULD_THROW_ERROR_WHILE_PERFORMING_CHECKOUT = true
const val SHOULD_RECEIVE_RESULT_ON_NEW_ACTIVITY = true

fun iPayCheckoutPayment(paymentUrl : String) {
    try {
        val checkoutState = performCheckout(paymentUrl, SHOULD_THROW_ERROR_WHILE_PERFORMING_CHECKOUT, SHOULD_RECEIVE_RESULT_ON_NEW_ACTIVITY) 
    }catch(e: Exception) {
        // perform checkout failed exceptions
    }
}

iv. Check the status of checkout

On your onActivityResult you will receive the CheckoutStatus and the checkoutId.

// sample java checkout code.
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    final int iPayCheckoutRequestCode = IPaySDK.getCheckoutRequestCode();
    super.onActivityResult(requestCode, resultCode, data);
		switch (requestCode) {
			case iPayCheckoutRequestCode:
				switch (resultCode) {
					case RESULT_OK:
					    if (data != null) {
					        final int checkoutId = data.getStringExtra(IPaySDK.CHECKOUT_ID_KEY);
					        final CheckoutStatus checkoutStatus = (CheckoutStatus) data.getSerializableExtra(IPaySDK.CHECKOUT_STATUS_KEY);
					        switch(checkoutStatus) {
					            case SUCCESS:
					                // call success callback url.
					                break;
					            case FAILED:
					                // call failed callback url.
					                break;
					            case CANCELLED:
					                // call cancelled callback url.
					                break;					                
					        }
					    }
					break;
				}
			break;
		}
}

// sample kotlin checkout code.
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    val iPayCheckoutRequestCode = IPaySDK.getCheckoutRequestCode()
    when (requestCode) {
        iPayCheckoutRequestCode -> {
            when (resultCode) {
                RESULT_OK -> {
                    if (data != null) {
                        val checkoutId = data.getStringExtra(IPaySDK.CHECKOUT_ID_KEY)
                        val checkoutStatus = data.getSerializableExtra(IPaySDK.CHECKOUT_STATUS_KEY)  as CheckoutStatus
                        when(checkoutStatus) {
                            SUCCESS -> {
                                // call success callback url.
                            }
                            FAILED -> {
                                // call failed callback url.
                            }
                            CANCELLED -> {
                                // call cancelled callback url.
                            }
                        }                  
                    }
                }                
            }
        }
    }
}

Important: You have to call the success/cancelled/failed callback api manually depending on the CheckoutStatus

If you are willing to receive result in a new activity, get checkoutStatus and checkoutId from intent.

// sample java checkout code.
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if(getIntent() != null) {
        final int checkoutId = getIntent().getStringExtra(IPaySDK.CHECKOUT_ID_KEY);
        final CheckoutStatus checkoutStatus = (CheckoutStatus) getIntent().getSerializableExtra(IPaySDK.CHECKOUT_STATUS_KEY);
        switch(checkoutStatus) {
            case SUCCESS:
                // call success callback url.
                break;
            case FAILED:
                // call failed callback url.
                break;
            case CANCELLED:
                // call cancelled callback url.
                break;					                
        }
    }
}

// sample kotlin checkout code.
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val checkoutId = intent.getStringExtra(IPaySDK.CHECKOUT_ID_KEY)
    val checkoutStatus = intent.getSerializableExtra(IPaySDK.CHECKOUT_STATUS_KEY) as CheckoutStatus
    when(checkoutStatus) {
        SUCCESS -> {
            // call success callback url.
        }
        FAILED -> {
            // call failed callback url.
        }
        CANCELLED ->{
         // call cancelled callback url.
        }
    }
}