feat: add get token service to ios sdk (#74)

docs/concepts/elements.mdx

@@ -52,11 +52,7 @@ data directly within your application code.
 Using one of our [SDKs](#elements-sdks), sensitive data can be securely retrieved and applied to one or more Elements within your UI.
 The SDK will manage encapsulating the sensitive data so that your application can reference these value without having direct access to it.
 
-To get started revealing sensitive data to your users, check out our guides:
-
-- [Reveal Data on Web](/docs/sdks/web/javascript/methods#detokenization)
-- [Reveal Data on Android](/docs/sdks/mobile/android/services#gettoken)
-- [Reveal Data on iOS](/docs/sdks/mobile/ios/services#proxy)
+To get started revealing sensitive data to your users, check out our [Reveal Tokenized Data](/docs/guides/share/reveal-tokenized-data) guide.
 
 ## Elements SDKs
 

docs/sdks/mobile/ios/services.mdx

@@ -85,6 +85,38 @@ BasisTheoryElements.createSession(
 
 The callback provided calls your function with a `data` of type [CreateSessionResponse](https://github.com/Basis-Theory/basistheory-swift/blob/master/docs/CreateSessionResponse.md), and an `error` of type [Error](#errors).
 
+### getTokenById
+
+This function wraps the [get a token API endpoint](/docs/api/tokens/#get-a-token) to retrieve a single strongly typed token.
+The token's data is transformed to value references which you can use to [set the value](/docs/sdks/mobile/ios/types#methods) of your elements without touching
+the plaintext value and pulling your application into compliance scope.
+
+```swift showLineNumbers
+BasisTheoryElements.getTokenById(
+    id: "<YOUR TOKEN ID>",
+    apiKey: "<YOUR API KEY>",
+) { data, error in ... }
+```
+
+The callback provided calls your function with a:
+* `error` of type [Error](#errors)
+* `data` of type `JSON` - `JSON` is a data structure that has dynamic member lookup capabilities. This allows you to traverse a `token` without giving you access to read any sensitive values in `token.data` which means you stay compliant. 
+
+To show a value from the token `data`, traverse the JSON using dot or bracket notation and retrieve the value using the `elementValueReference` property. 
+Below is an example of how you do that and set the value reference into a Text Element.
+
+```swift showLineNumbers
+@IBOutlet private weak var myTextElement: TextElementUITextField!
+...
+
+BasisTheoryElements.getTokenById(
+    id: "<YOUR TOKEN ID>",
+    apiKey: "<YOUR API KEY>",
+) { data, error in 
+    myTextElement.setValue(elementValueReference: data!.data!.nested!.property!.elementValueReference)
+}
+```
+
 ### proxy
 
 Proxy provides a simple way to retrieve data back into an element utilizing our [proxy](/docs/api/proxies) service. To accomplish this, simply construct your `proxy` request like this:

docs/sdks/mobile/ios/types.mdx

@@ -20,7 +20,7 @@ import Combine
 class TokenizeName: UIViewController {
     @IBOutlet weak var nameTextField: TextElementUITextField!
     @IBOutlet weak var output: UITextView!
-
+ 
     @IBAction func tokenize(_ sender: Any) {
         let body: [String: Any] = [
             "data": [
@@ -45,11 +45,27 @@ class TokenizeName: UIViewController {
 }
 ```
 
-| Configuration | Defaults |
-| --- | --- |
+### Configuration
+
+The `TextElementUITextField` extends the native `UITextField` from UIKit, so all standard properties and attributes supported by `UITextField` are supported by `TextElementUITextField`.
+
+#### Properties
+
+The following additional properties are supported when programmatically interacting with a `TextElementUITextField`:
+
+| Name | Type |
+| ---------- | --- |
 | validation | No default validation. Always valid in [ElementEvent](/docs/sdks/mobile/ios/events#elementevent). |
-| mask | No default [mask](/docs/sdks/mobile/ios/options#mask). [Mask](/docs/sdks/mobile/ios/options#mask) can be overridden. |
-| transform | No default [transform](/docs/sdks/mobile/ios/options#transform). [Transform](/docs/sdks/mobile/ios/options#transform) can be overriden. |
+| mask       | No default [mask](/docs/sdks/mobile/ios/options#mask). [Mask](/docs/sdks/mobile/ios/options#mask) can be overridden. |
+| transform  | No default [transform](/docs/sdks/mobile/ios/options#transform). [Transform](/docs/sdks/mobile/ios/options#transform) can be overriden. |
+
+#### Methods
+
+| Signature                                                | Description                                                                                                                                                                  |
+|----------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `setValue(elementValueReference: ElementValueReference)` | Sets the element's text to the value referenced by the provided ElementValueReference.                                                                                                  |
+| `setValueRef(element: TextElementUITextField)`           | Binds the provided `element: TextElementUITextField` instance as a value source for this element, keeping the value of this element in sync with any changes made to the other element. |
+
 
 ## CardNumberUITextField
 
@@ -89,6 +105,12 @@ class TokenizeCardNumber: UIViewController {
 }
 ```
 
+### Configuration
+
+The `CardNumberUITextField` element type extends the `TextElementUITextField` class, so all properties and attributes supported by `TextElementUITextField` are also supported here.
+
+By default, this element is configured with:
+
 | Configuration | Defaults |
 | --- | --- |
 | validation | Input must be Luhn valid and be an acceptable length for the card brand. |
@@ -143,6 +165,12 @@ class TokenizeCardExpirationDate: UIViewController {
 }
 ```
 
+### Configuration
+
+The `CardExpirationDateUITextField` element type extends the `TextElementUITextField` class, so all properties and attributes supported by `TextElementUITextField` are also supported here.
+
+By default, this element is configured with:
+
 | Configuration | Defaults |
 | --- | --- |
 | validation | Input must be the current month and year or later. |
@@ -203,6 +231,12 @@ class TokenizeCVC: UIViewController {
 }
 ```
 
+### Configuration
+
+The `CardVerificationCodeUITextField` element type extends the `TextElementUITextField` class, so all properties and attributes supported by `TextElementUITextField` are also supported here.
+
+By default, this element is configured with:
+
 | Configuration | Defaults |
 | --- | --- |
 | validation | No default validation. Always valid in [ElementEvent](/docs/sdks/mobile/ios/events#elementevent). |