Mobile Buy SDK
The Mobile Buy SDK makes it easy to create custom storefronts in your mobile app. The SDK connects to the Shopify platform using the Storefront GraphQL API and supports a wide range of native storefront experiences.
Documentation
You can generate complete .html
and .docset
documentation by running the Documentation
scheme. You can then use a documentation browser like Dash to access the .docset
artifact, or browse the HTML directly in the Docs/Buy
and Docs/Pay
directories.
The documentation is generated using Jazzy.
Installation
Download the latest version
Swift Package Manager
This is the recommended approach of integration the SDK with your app. You can follow Apple's guide for adding a package dependency to your app for a thorough walkthrough.
Dynamic Framework Installation
- Add
Buy
as a git submodule by running:
git submodule add git@github.com:Shopify/mobile-buy-sdk-ios.git
- Ensure that all submodules of
Buy SDK
have also been updated by running:
git submodule update --init --recursive
- Drag the
Buy.xcodeproj
into your application project. - Add Buy.framework target as a dependency:
- Navigate to Build Phases > Target Dependencies.
- Add
Buy.framework
.
- Link
Buy.framework
:
- Navigate to Build Phases > Link Binary With Libraries.
- Add
Buy.framework
.
- Make sure that the framework is copied into the bundle:
- Navigate to Build Phases > New Copy Files Phase.
- From the Destination dropdown, select Frameworks.
- Add
Buy.framework
.
- Import into your project files using
import Buy
.
See the Storefront sample app for an example of how to add the Buy
target a dependency.
Carthage
- Add the following line to your Cartfile:
github "Shopify/mobile-buy-sdk-ios"
- Run
carthage update
. - Follow the steps to link the dynamic framework that Carthage produced.
- Import the SDK module:
import Buy
CocoaPods
- Add the following line to your podfile:
pod "Mobile-Buy-SDK"
- Run
pod install
. - Import the SDK module:
import MobileBuySDK
Note: If you've forked this repo and are attempting to install from your own git destination, commit, or branch, be sure to include "submodules: true" in the line of your Podfile
Getting started
The Buy SDK is built on GraphQL. The SDK handles all the query generation and response parsing, exposing only typed models and compile-time checked query structures. It doesn't require you to write stringed queries, or parse JSON responses.
You don't need to be an expert in GraphQL to start using it with the Buy SDK (but it helps if you've used it before). The sections below provide a brief introduction to this system, and some examples of how you can use it to build secure custom storefronts.
Migration from SDK v2.0
The previous version of the Mobile Buy SDK (version 2.0) is based on a REST API. With version 3.0, Shopify is migrating the SDK from REST to GraphQL.
Unfortunately, the specifics of generation GraphQL models make it almost impossible to create a migration path from v2.0 to v3.0 (domains models are not backwards compatible). However, the main concepts are the same across the two versions, such as collections, products, checkouts, and orders.
Code Generation
The Buy SDK is built on a hierarchy of generated classes that construct and parse GraphQL queries and responses. These classes are generated manually by running a custom Ruby script that relies on the GraphQL Swift Generation library. Most of the generation functionality and supporting classes live inside the library. It works by downloading the GraphQL schema, generating Swift class hierarchy, and saving the generated files to the specified folder path. In addition, it provides overrides for custom GraphQL scalar types like DateTime
.
Request Models
All generated request models are derived from the GraphQL.AbstractQuery
type. Although this abstract type contains enough functionality to build a query, you should never use it directly. Instead, rely on the typed methods provided in the generated subclasses.
The following example shows a sample query for a shop's name:
let query = Storefront.buildQuery { $0
.shop { $0
.name()
}
}
Never use the abstract class directly:
let shopQuery = GraphQL.AbstractQuery()
shopQuery.addField(field: "name")
let query = GraphQL.AbstractQuery()
query.addField(field: "shop", subfields: shopQuery)
Both of the above queries produce identical GraphQL queries (see below), but the former approach provides auto-completion and compile-time validation against the GraphQL schema. It will surface an error if a requested field doesn't exist, isn't the correct type, or is deprecated. You also might have noticed that the former approach resembles the GraphQL query language structure (this is intentional). The query is both easier to write and much more legible.
query {
shop {
name
}
}
Response models
All generated response models are derived from the GraphQL.AbstractResponse
type. This abstract type provides a similar key-value type interface to a Dictionary
for accessing field values in GraphQL responses. Just like GraphQL.AbstractQuery
, you should never use these accessors directly, and instead rely on typed, derived properties in generated subclasses.
The following example builds on the earlier example of accessing the result of a shop name query:
let name: String = response.shop.name
Never use the abstract class directly:
let response: GraphQL.AbstractResponse
let shop = response.field("shop") as! GraphQL.AbstractResponse
let name = shop.field("name") as! String
Again, both of the approaches produce the same result, but the former case is preferred: it requires no casting since it already knows about the expected type.
The Node
protocol
The GraphQL schema defines a Node
interface that declares an id
field on any conforming type. This makes it convenient to query for any object in the schema given only its id
. The concept is carried across to the Buy SDK as well, but requires a cast to the correct type. You need to make sure that the Node
type is of the correct type, otherwise casting to an incorrect type will return a runtime exception.
Given this query:
let id = GraphQL.ID(rawValue: "gid://shopify/Product/123")
let query = Storefront.buildQuery { $0
.node(id: id) { $0
.onProduct { $0
.id()
.title()
}
}
}
The Storefront.Product
requires a cast:
let product = response.node as! Storefront.Product
Aliases
Aliases are useful when a single query requests multiple fields with the same names at the same nesting level, since GraphQL allows only unique field names. Multiple nodes can be queried by using a unique alias for each one:
let query = Storefront.buildQuery { $0
.node(aliasSuffix: "collection", id: GraphQL.ID(rawValue: "NkZmFzZGZhc")) { $0
.onCollection { $0
}
}
.node(aliasSuffix: "product", id: GraphQL.ID(rawValue: "GZhc2Rm")) { $0
.onProduct { $0
}
}
}
Accessing the aliased nodes is similar to a plain node:
let collection = response.aliasedNode(aliasSuffix: "collection") as! Storefront.Collection
let product = response.aliasedNode(aliasSuffix: "product") as! Storefront.Product
Learn more about GraphQL aliases.
Graph.Client
The Graph.Client
is a network layer built on top of URLSession
that executes query
and mutation
requests. It also simplifies polling and retrying requests. To get started with Graph.Client
, you need the following:
- Your shop's
.myshopify.com
domain - Your API key, which you can find in your shop's admin page
- A
URLSession
(optional), if you want to customize the configuration used for network requests or share your existing URLSession
with the Graph.Client
- (optional) The buyer's current locale. Supported values are limited to locales available to your shop.
let client = Graph.Client(
shopDomain: "shoes.myshopify.com",
apiKey: "dGhpcyBpcyBhIHByaXZhdGUgYXBpIGtleQ"
)
If your store supports multiple languages, then the Storefront API can return translated resource types and fields. Learn more about translating content.
let client = Graph.Client(
shopDomain: "shoes.myshopify.com",
apiKey: "dGhpcyBpcyBhIHByaXZhdGUgYXBpIGtleQ",
locale: Locale.current
)
GraphQL specifies two types of operations: queries and mutations. The Client
exposes these as two type-safe operations, although it also offers some conveniences for retrying and polling in each one.
Queries
Semantically, a GraphQL query
operation is equivalent to a GET
RESTful call. It guarantees that no resources will be mutated on the server. With Graph.Client
, you can perform a query operation using:
public func queryGraphWith(_ query: Storefront.QueryRootQuery, retryHandler: RetryHandler<Storefront.QueryRoot>? = default, completionHandler: QueryCompletion) -> Task
The following example shows how you can query for a shop's name:
let query = Storefront.buildQuery { $0
.shop { $0
.name()
}
}
let task = client.queryGraphWith(query) { response, error in
if let response = response {
let name = response.shop.name
} else {
print("Query failed: \(error)")
}
}
task.resume()
Learn more about GraphQL queries.
Mutations
Semantically a GraphQL mutation
operation is equivalent to a PUT
, POST
or DELETE
RESTful call. A mutation is almost always accompanied by an input that represents values to be updated and a query to fetch fields of the updated resource. You can think of a mutation
as a two-step operation where the resource is first modified, and then queried using the provided query
. The second half of the operation is identical to a regular query
request.
With Graph.Client
you can perform a mutation operation using:
public func mutateGraphWith(_ mutation: Storefront.MutationQuery, retryHandler: RetryHandler<Storefront.Mutation>? = default, completionHandler: MutationCompletion) -> Task
The following example shows how you can reset a customer's password using a recovery token:
let customerID = GraphQL.ID(rawValue: "YSBjdXN0b21lciBpZA")
let input = Storefront.CustomerResetInput.create(resetToken: "c29tZSB0b2tlbiB2YWx1ZQ", password: "abc123")
let mutation = Storefront.buildMutation { $0
.customerReset(id: customerID, input: input) { $0
.customer { $0
.id()
.firstName()
.lastName()
}
.userErrors { $0
.field()
.message()
}
}
}
let task = client.mutateGraphWith(mutation) { response, error in
if let mutation = response?.customerReset {
if let customer = mutation.customer, !mutation.userErrors.isEmpty {
let firstName = customer.firstName
let lastName = customer.lastName
} else {
print("Failed to reset password. Encountered invalid fields:")
mutation.userErrors.forEach {
let fieldPath = $0.field?.joined() ?? ""
print(" \(fieldPath): \($0.message)")
}
}
} else {
print("Failed to reset password: \(error)")
}
}
task.resume()
A mutation will often rely on some kind of user input. Although you should always validate user input before posting a mutation, there are never guarantees when it comes to dynamic data. For this reason, you should always request the userErrors
field on mutations (where available) to provide useful feedback in your UI regarding any issues that were encountered in the mutation query. These errors can include anything from Invalid email address
to Password is too short
.
Learn more about GraphQL mutations.
Retry
Both queryGraphWith
and mutateGraphWith
accept an optional RetryHandler<R: GraphQL.AbstractResponse>
. This object encapsulates the retry state and customization parameters for how the Client
will retry subsequent requests (such as after a set delay, or a number of retries). By default, the retryHandler
is nil and no retry behavior will be provided. To enable retry or polling, create a handler with a condition. If the handler.condition
and handler.canRetry
evaluate to true
, then the Client
will continue executing the request:
let handler = Graph.RetryHandler<Storefront.QueryRoot>() { (query, error) -> Bool in
if myCondition {
return true
}
return false
}
The retry handler is generic, and can handle both query
and mutation
requests equally well.
Caching
Network queries and mutations can be both slow and expensive. For resources that change infrequently, you might want to use caching to help reduce both bandwidth and latency. Since GraphQL relies on POST
requests, we can't easily take advantage of the HTTP caching that's available in URLSession
. For this reason, the Graph.Client
is equipped with an opt-in caching layer that can be enabled client-wide or on a per-request basis.
IMPORTANT: Caching is provided only for query
operations. It isn't available for mutation
operations or for any other requests that provide a retryHandler
.
There are four available cache policies:
.cacheOnly
- Fetch a response from the cache only, ignoring the network. If the cached response doesn't exist, then return an error..networkOnly
- Fetch a response from the network only, ignoring any cached responses..cacheFirst(expireIn: Int)
- Fetch a response from the cache first. If the response doesn't exist or is older than expireIn
, then fetch a response from the network.networkFirst(expireIn: Int)
- Fetch a response from the network first. If the network fails and the cached response isn't older than expireIn
, then return cached data instead.
Enable client-wide caching
You can enable client-wide caching by providing a default cachePolicy
for any instance of Graph.Client
. This sets all query
operations to use your default cache policy, unless you specify an alternate policy for an individual request.
In this example, we set the client's cachePolicy
property to cacheFirst
:
let client = Graph.Client(shopDomain: "...", apiKey: "...")
client.cachePolicy = .cacheFirst
Now, all calls to queryGraphWith
will yield a task with a .cacheFirst
cache policy.
If you want to override a client-wide cache policy for an individual request, then specify an alternate cache policy as a parameter of queryGraphWith
:
let task = client.queryGraphWith(query, cachePolicy: .networkFirst(expireIn: 20)) { query, error in
}
In this example, the task
cache policy changes to .networkFirst(expireIn: 20)
, which means that the cached response will be valid for 20 seconds from the time the response is received.
Errors
The completion for either a query
or mutation
request will always contain an optional Graph.QueryError
that represents the current error state of the request. It's important to note that error
and response
are NOT mutually exclusive. It is perfectly valid to have a non-nil error and response. The presence of an error can represent both a network error (such as a network error, or invalid JSON) or a GraphQL error (such as invalid query syntax, or a missing parameter). The Graph.QueryError
is an enum
, so checking the type of error is trivial:
let task = client.queryGraphWith(query) { response, error in
if let response = response {
} else {
if let error = error, case .http(let statusCode) = error {
print("Query failed. HTTP error code: \(statusCode)")
}
}
}
task.resume()
If the error is of type .invalidQuery
, then an array of Reason
objects is returned. These will provide more in-depth information about the query error. Keep in mind that these errors are not meant to be displayed to the end-user. They are for debugging purposes only.
The following example shows a GraphQL error response for an invalid query:
{
"errors": [
{
"message": "Field 'Shop' doesn't exist on type 'QueryRoot'",
"locations": [
{
"line": 2,
"column": 90
}
],
"fields": ["query CollectionsWithProducts", "Shop"]
}
]
}
Learn more about GraphQL errors.
Common Operations
Getting started with any SDK can be confusing. The purpose of this section is to explore all areas of the Buy SDK that might be necessary to build a custom storefront on iOS and provide a solid starting point for your own implementation.
In this section we're going to assume that you've set up a client somewhere in your source code. Although it's possible to have multiple instances of Graph.Client
, reusing a single instance offers many behind-the-scenes performance improvements:
let client: Graph.Client
Retrieving Shop Details
Before you display products to the user, you typically need to obtain various metadata about your shop. This can be anything from a currency code to your shop's name:
let query = Storefront.buildQuery { $0
.shop { $0
.name()
}
}
let task = client.queryGraphWith(query) { response, error in
let name = response?.shop.name
}
task.resume()
The corresponding GraphQL query looks like this:
query {
shop {
name
}
}
Retrieving Collections and Products
In our sample custom storefront, we want to display a collection with a preview of several products. The following query requests the first 10 collections, and the first 10 products in each collection.
let query = Storefront.buildQuery { $0
.collections(first: 10) { $0
.nodes { $0
.id()
.title()
.products(first: 10) { $0
.nodes { $0
.id()
.title()
.productType()
.description()
}
}
}
}
}
let task = client.queryGraphWith(query) { response, error in
if let collections = response?.collections.nodes {
collections.forEach { collection in
let products = collection.products.nodes
}
}
}
task.resume()
The corresponding GraphQL query looks like this:
{
collections(first: 10) {
nodes {
id
title
products(first: 10) {
nodes {
id
title
productType
description
}
}
}
}
}
Retrieve a Product's Details
You will likely want to have a detailed product page with images, variants, and descriptions. Once you have a product's ID or handle
value, we can request it directly.
let query = Storefront.buildQuery { $0
.product(handle: "t-shirt") { $0
.title()
.description()
.images(first: 10) { $0
.nodes { $0
.url()
}
}
.variants(first: 50) { $0
.nodes { $0
.id()
.title()
.price { $0
.amount()
.currencyCode()
}
.availableForSale()
}
}
}
}
let task = client.queryGraphWith(query) { response, error in
let product = response?.product
let images = product?.images.nodes
let variants = product?.variants.nodes
}
task.resume()
The corresponding GraphQL query looks like this:
{
product(handle: "t-shirt") {
title
description
images(first: 10) {
nodes {
url
}
}
variants(first: 50) {
nodes {
id
title
price {
amount
currencyCode
}
availableForSale
}
}
}
}
Search and Filtering
Some fields and connections accept search terms via the query
parameter. For example, you can provide a query
to search for collections that contain a specific search term in any of their fields.
The following example shows how you can find collections that contain the word "shoes":
let query = Storefront.buildQuery { $0
.collections(first: 10, query: "shoes") { $0
.nodes { $0
.id()
.title()
.description()
}
}
}
For more information on the syntax and capabilities of search queries, see shopify.dev.
Managing Carts
Once you have your products displayed, you need a way for your prospective buyers to purchase them. This process starts with creating a Cart
.
Creating a Cart
To create a Cart
, you will use the cartCreate
mutation. If you do not specify any input arguments, you will simply get an empty Cart
.
let createCartMutation = Storefront.buildMutation { $0
.cartCreate { $0
.cart { $0
.id()
}
}
}
However, you can also create a Cart
with an initial set of line items and other attributes.
let aProductVariantID =
let linesInput: [Storefront.CartLineInput] = [
.create(merchandiseId: aProductVariantID, quantity: .value(5))
]
let buyerIdentityInput = Storefront.CartBuyerIdentityInput.create(
email: .value("your.customer@example.com")
)
let cartInput = Storefront.CartInput.create(
lines: .value(linesInput), buyerIdentity: .value(buyerIdentityInput)
)
let createCartMutation = Storefront.buildMutation { $0
.cartCreate(input: cartInput) { $0
.cart { $0
.id()
}
}
}
Modifying a Cart
Once you have a Cart
object (or at least an ID to one), you can modify its contents and attributes using several available mutations. Below are a few common examples.
Removing a Line Item
let removeCartLineMutation = Storefront.buildMutation { $0
.cartLinesRemove(cartId: myCartID, lineIds: [myCartLineID]) { $0
.cart { $0
.id()
}
}
}
Adding a Discount Code
let updateDiscountCodeMutation = Storefront.buildMutation { $0
.cartDiscountCodesUpdate(cartId: myCartID, discountCodes: ["10OFF"]) { $0
.cart { $0
.id()
}
}
}
For more information about managing carts, see shopify.dev.
Proceeding to Checkout
Once you have a Cart
object that the buyer is ready to purchase, you first must retrieve the cart's checkoutUrl
property.
let cartQuery = Storefront.buildQuery { $0
.cart(id: aCartID) { $0
.checkoutUrl()
}
}
Once you have the checkout URL, you have a few options to begin the checkout process.
Our recommended approach is to use our Mobile Checkout SDK which provides a native look and feel to Shopify's checkout flow.
import UIKit
import ShopifyCheckout
class MyViewController: UIViewController {
func proceedToCheckout() {
let checkoutURL =
ShopifyCheckout.present(
checkout: checkoutURL, from: self, delegate: self
)
}
}
Alternatively, you can open the checkout URL directly in a SFSafariViewController
, via UIApplication.shared.open(url:)
, or other web browser.
import UIKit
import SafariServices
class MyViewController: UIViewController {
func proceedToCheckout() {
let checkoutURL =
present(SFSafariViewController(url: checkoutURL), animated: true)
}
}
Customer Authentication
Any customer who has an account can log in to your shop. All log-in operations are mutation
requests that exchange customer credentials for an access token. You can log in your customers using the customerAccessTokenCreate
mutation. Keep in mind that the return access token will eventually expire. The expiry Date
is provided by the expiresAt
property of the returned payload.
let input = Storefront.CustomerAccessTokenCreateInput.create(
email: "john.smith@gmail.com", password: "123456"
)
let mutation = Storefront.buildMutation { $0
.customerAccessTokenCreate(input: input) { $0
.customerAccessToken { $0
.accessToken()
.expiresAt()
}
.userErrors { $0
.field()
.message()
}
}
}
Optionally, you can refresh the custom access token periodically using the customerAccessTokenRenew
mutation.
IMPORTANT: It is your responsibility to securely store the customer access token. We recommend using Keychain and best practices for storing secure data.
Retrieve Customer Details
Once you have a valid customer access token, you can use it to retrieve the details of the authenticated customer.
let query = Storefront.buildQuery { $0
.customer(customerAccessToken: token) { $0
.id()
.firstName()
.lastName()
.email()
}
}
Contributions
We welcome contributions. Please follow the steps in our contributing guidelines.
Help
For help with the Mobile Buy SDK, see the iOS Buy SDK documentation or post questions on our forum, in the Shopify APIs & SDKs
section.
License
The Mobile Buy SDK is provided under an MIT License.