# Add a line item

Add itemized product details to a Tap to Pay on iPhone sale using the CoreLineItem object, including a per-item tax.

**Prerequisites:** [Authentication](/api/authentication) · [Run a sale](/guides/payments/tap-to-pay-on-iphone/run-a-sale)

To provide more information about a sale, you can add individual line items. Create a `CoreLineItem` object for each item, and assign the collection to the `CoreSale` object's lineItems array.

The `CoreLineItem` object includes the following fields:

| **Field** | **Description** |
| --- | --- |
| `commodityCode` | Commodity code of the item. |
| `productCode` | Product code of the item. |
| `itemDescription` | Description of the item. |
| `unitOfMeasure` | Unit of measure. A three-letter code used in international trade. For more information about the values that you can use, go to [Units of measurement](/knowledge/api-basics/unit-of-measure). |
| `unitPrice` | Price for each unit of measure before any taxes or discounts |
| `quantity` | Number of units. |
| `discountRate` | Discount percentage to apply to the item. |
| `taxes` | The list of taxes to apply to the item. For more information, go to [Add a tax to a line item](#add-a-tax-to-a-line-item). |

**Important:** The SDK doesn't calculate the sale amount from the line items for you. Set `sale.amount` to the subtotal of all your line items. The subtotal is the unit price multiplied by the quantity, minus any discount.

The following example adds a line item to a sale:

**`Swift`**

```swift
let item = CoreLineItem()
item.commodityCode = "AA"
item.productCode = "BB"
item.itemDescription = "Bread"
item.unitOfMeasure = EA
item.unitPrice = 2.00
item.quantity = 2
item.discountRate = 0
item.taxes = []

let lineItems = NSMutableArray()
lineItems.add(item)

let sale = CoreSale()
sale.amount = NSNumber(value: 4.00)
sale.transactionInputMethod = TAP
sale.lineItems = lineItems

terminal.processSale(sale)
```

**`Objective-C`**

```objectivec
CoreLineItem *item = [[CoreLineItem alloc] init];
item.commodityCode = @"AA";
item.productCode = @"BB";
item.itemDescription = @"Bread";
item.unitOfMeasure = EA;
item.unitPrice = @2.00;
item.quantity = @2;
item.discountRate = @0;
item.taxes = [NSMutableArray array];

NSMutableArray *lineItems = [NSMutableArray array];
[lineItems addObject:item];

CoreSale *sale = [[CoreSale alloc] init];
sale.amount = @4.00;
sale.transactionInputMethod = TAP;
sale.lineItems = lineItems;

[[WTPSTerminal singleton] processSale:sale];
```

<a id="add-a-tax-to-a-line-item"></a>
## Add a tax to a line item

To apply a tax to an individual line item, add a `CoreTax` to the item's `taxes` array. To calculate the tax amount from a percentage, use `CoreUtil`, and then set a global `CoreTax` on the sale with the total tax amount.

**`Swift`**

```swift
let tax = CoreTax()
tax.percentage = 10
let taxAmount = (CoreUtil.singleton() as! CoreUtil).calcTax(
    tax.percentage,
    withAmount: item.unitPrice,
    with: terminal.currency
)
tax.amount = taxAmount
item.taxes = [tax]

let globalTax = CoreTax()
globalTax.amount = taxAmount
globalTax.name = "Item tax"
sale.tax = globalTax
```

**`Objective-C`**

```objectivec
CoreTax *tax = [[CoreTax alloc] init];
tax.percentage = @10;
NSNumber *taxAmount = [[CoreUtil singleton] calcTax:tax.percentage
                                        withAmount:item.unitPrice
                                      withCurrency:[[WTPSTerminal singleton] getCurrency]];
tax.amount = taxAmount;
item.taxes = [NSMutableArray arrayWithObject:tax];

CoreTax *globalTax = [[CoreTax alloc] init];
globalTax.amount = taxAmount;
globalTax.name = @"Item tax";
sale.tax = globalTax;
```

**Note:** If you want to apply a tax to the whole sale instead of a single line item, go to [Add a tax](/guides/payments/tap-to-pay-on-iphone/add-a-tax).

The following example runs a complete sale with a line item and a tax applied to that line item:

**`Swift`**

```swift
guard terminal.getDevice() != NODEVICE else {
    return
}

let item = CoreLineItem()
item.commodityCode = "AA"
item.productCode = "BB"
item.itemDescription = "Bread"
item.unitOfMeasure = EA
item.unitPrice = 2.00
item.quantity = 2
item.discountRate = 0

let tax = CoreTax()
tax.percentage = 10
tax.amount = (CoreUtil.singleton() as! CoreUtil).calcTax(
    tax.percentage,
    withAmount: item.unitPrice,
    with: terminal.currency
)
item.taxes = [tax]

let lineItems = NSMutableArray()
lineItems.add(item)

let globalTax = CoreTax()
globalTax.amount = tax.amount
globalTax.name = "Item tax"

let sale = CoreSale()
sale.amount = 4.00
sale.transactionInputMethod = TAP
sale.orderId = "YOUR_ORDER_REFERENCE"
sale.lineItems = lineItems
sale.tax = globalTax

terminal.processSale(sale)
```

**`Objective-C`**

```objectivec
if ([[WTPSTerminal singleton] getDevice] == NODEVICE) {
    return;
}

CoreLineItem *item = [[CoreLineItem alloc] init];
item.commodityCode = @"AA";
item.productCode = @"BB";
item.itemDescription = @"Bread";
item.unitOfMeasure = EA;
item.unitPrice = @2.00;
item.quantity = @2;
item.discountRate = @0;

CoreTax *tax = [[CoreTax alloc] init];
tax.percentage = @10;
tax.amount = [[CoreUtil singleton] calcTax:tax.percentage
                                withAmount:item.unitPrice
                              withCurrency:[[WTPSTerminal singleton] getCurrency]];
item.taxes = [NSMutableArray arrayWithObject:tax];

NSMutableArray *lineItems = [NSMutableArray array];
[lineItems addObject:item];

CoreTax *globalTax = [[CoreTax alloc] init];
globalTax.amount = tax.amount;
globalTax.name = @"Item tax";

CoreSale *sale = [[CoreSale alloc] init];
sale.amount = @4.00;
sale.transactionInputMethod = TAP;
sale.orderId = @"YOUR_ORDER_REFERENCE";
sale.lineItems = lineItems;
sale.tax = globalTax;

[[WTPSTerminal singleton] processSale:sale];
```