Get Started with Swift SDK

This guide will help you get started with Contentstack Swift SDK to build apps powered by Contentstack.

Prerequisites

To get started with Swift SDK, you will need the following:

  • The latest version of Xcode 11.0
  • Swift 5.0
  • iOS 8 or later

SDK Installation and Setup

Contentstack offers two regions (the US and European) as data centers to store customers' account details and data. Both regions are independent of each other, and therefore, have a dedicated set of instructions to use SDKs offered by Contentstack.

To use SDKs for the European region, you will have to make certain changes in the configuration of the SDK, as detailed below, and the rest of the instructions remain the same.

To add the Contentstack Swift SDK to your existing project, perform the following steps:

Configure the SDK

You can configure the SDK installation using CocoaPods.

Using CocoaPods

Add the following line to your Podfile:

pod 'ContentstackSwift'

Then, run the command given below to get the latest release of Contentstack.

pod install

Import Header/Module

import ContentstackSwift

Initializing your SDK

To initialize the SDK, specify the application context, the stack’s API key, Delivery token, and name of the environment where you will publish the content, as shown in the snippet below:

let stack:Stack = Contentstack.stack(apiKey: API_KEY, deliveryToken: DELIVERY_TOKEN, environment: ENVIRONMENT)

For Setting the European Region:

If you want to set and use the SDK for the European region, refer to the code below:

let stack:Stack = Contentstack.stack(apiKey: API_KEY, deliveryToken: DELIVERY_TOKEN, environment: ENVIRONMENT, region: .eu)

Cache Policies

The cache policies allow you to define the source from where the SDK will retrieve data. Based on the selected policy, the SDK can get the data from the cache, network, or both.

Let’s look at the various cache policies available for use:

POLICIESDESCRIPTION
networkOnly (default)If you set networkOnly as the cache policy, the SDK retrieves data through a network call and saves the retrieved data in the cache. This is set as the default policy.
cacheElseNetworkIf you set cacheElseNetwork as the cache policy, the SDK gets data from the cache. However, if it fails to retrieve data from the cache, it makes a network call.
networkElseCacheIf you set networkElseCache as the cache policy, the SDK gets data using a network call. However, if the call fails, it retrieves data from the cache
cacheThenNetworkIf you set cacheThenNetwork as the cache policy, the SDK gets data from the cache, and then makes a network call. (A success callback will be invoked twice.)
cacheOnlyIf you set cacheOnly as the cache policy, the SDK gets data from the cache.

You can set a cache policy on an entry, asset, and/or a query object.

Setting a Cache Policy on an Entry

To set the cache policy to all the query objects of an entry, refer to the code below:

let stack = Contentstack.stack(apiKey: apiKey,
              deliveryToken: deliveryToken,
              environment: environment)
 
let entry = stack.contentType(uid: contentTypeUID).entry(uid: UID)
entry.cachePolicy = .networkElseCache
entry.fetch { (result: Result, response: ResponseType) in
     switch result {
     case .success(let model):
          //Model retrieve from API
     case .failure(let error):
          //Error Message
     }
}

Setting a Cache Policy on an Asset

To set the cache policy to all the query objects of an asset, refer to the code below:

let stack = Contentstack.stack(apiKey: apiKey,
              deliveryToken: deliveryToken,
              environment: environment)
 
let asset = stack.contentType(uid: contentTypeUID).asset(uid: UID)
asset.cachePolicy = .networkElseCache
asset.fetch { (result: Result, response: ResponseType) in
     switch result {
     case .success(let model):
          //Model retrieve from API
     case .failure(let error):
          //Error Message
     }
}

Setting a Cache Policy on a Query Object

To set/override a cache policy on a specific query object, refer to the code below:

let stack = Contentstack.stack(apiKey: apiKey,
             deliveryToken: deliveryToken,
             environment: environment)

let query = stack.contentType(uid: contentTypeUID).entry().query()
query.cachePolicy = .networkElseCache
query.find { (result: Result, Error>, response: ResponseType) in
      switch result {
      case .success(let contentstackResponse):
          // Contentstack response with EntryModel array in items.
      case .failure(let error):
          //Error Message
      }
  }

Basic Queries

Contentstack SDKs let you interact with the Content Delivery APIs and retrieve content from Contentstack. They are read-only in nature. The SDKs fetch and deliver content from the nearest server via Fastly, our powerful and robust CDN.

Get a Single Entry

To retrieve a single entry from a content type, refer to the code below:

let stack = Contentstack.stack(apiKey: apiKey,
              deliveryToken: deliveryToken,
              environment: environment)
 
stack.contentType(uid: contentTypeUID).entry(uid: UID)
.fetch { (result: Result, response: ResponseType) in
     switch result {
     case .success(let model):
          //Model retrieve from API
     case .failure(let error):
          //Error Message
     }
 }

Get Multiple Entries

To retrieve multiple entries of a particular content type, refer to the code below:

let stack = Contentstack.stack(apiKey: apiKey,
             deliveryToken: deliveryToken,
             environment: environment)

stack.contentType(uid: contentTypeUID).entry().query()
    .find { (result: Result, Error>, response: ResponseType) in
      switch result {
      case .success(let contentstackResponse):
          // Contentstack response with EntryModel array in items.
      case .failure(let error):
          //Error Message
      }
  }

These were the examples of some of the basic queries of the Swift SDK. For advanced queries, refer to the Contentstack Swift API reference.

Note: Currently, the Swift SDK does not support multiple content types referencing in a single query. For more information on how to query entries and assets, refer the Queries section of our Content Delivery API documentation.

Paginating Responses

In a single instance, the Get Multiple Entries query will retrieve only the first 100 items of the specified content type. You can paginate and retrieve the rest of the items in batches using the skip and limit parameters in subsequent requests.

let stack:Stack = Contentstack.stack(apiKey: stack_api_key, deliveryToken: delivery_token, environment: environment)

stack.contentType(uid: contentTypeUID).entry().query().skip(theFirst: 20).limit(to: 20).fetch { (result: Result, Error>, response: ResponseType) in 
    switch result 
    { 
          case .success(let contentstackResponse): 
          // Contentstack response with EntryModel array in items. 
         case .failure(let error): 
         //Error Message 
     } 
}

Limitations

  • We have a URL size limitation of 8KB on API Requests that hit our CDN services. Any Request URL that goes above this size limit will receive the 400 - Bad request error response. Please make sure you limit the size of your API Requests.

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