Use iOS SDK generated by API Gateway for a REST API in Objective-C or Swift

Extract the contents of the API Gateway-generated .zip file you downloaded earlier. Using the SimpleCalc API, you may want to rename the unzipped SDK folder to something like sdk_objc_simple_calc. In this SDK folder there is a README.md file and a Podfile file. The README.md file contains the instructions to install and use the SDK. This tutorial provides details about these instructions. The installation leverages CocoaPods to import required API Gateway libraries and other dependent Amazon Mobile SDK components. You must update the Podfile to import the SDKs into your app's Xcode project. The unarchived SDK folder also contains a generated-src folder that contains the source code of the generated SDK of your API.

Launch Xcode and create a new iOS Objective-C project. Make a note of the project's target. You will need to set it in the Podfile.

To import the Amazon Mobile SDK for iOS into the Xcode project by using CocoaPods, do the following:

1. Install CocoaPods by running the following command in a terminal window:

   sudo gem install cocoapods
   pod setup

2. Copy the Podfile file from the extracted SDK folder into the same directory containing your Xcode project file. Replace the following block:

   target '<YourXcodeTarget>' do
       pod 'AWSAPIGateway', '~> 2.4.7'
   end

   with your project's target name:

   target 'app_objc_simple_calc' do
       pod 'AWSAPIGateway', '~> 2.4.7'
   end

   If your Xcode project already contains a file named Podfile, add the following line of code to it:

   pod 'AWSAPIGateway', '~> 2.4.7'

3. Open a terminal window and run the following command:

   pod install

   This installs the API Gateway component and other dependent Amazon Mobile SDK components.

4. Close the Xcode project and then open the .xcworkspace file to relaunch Xcode.

5. Add all of the .h and .m files from the extracted SDK's generated-src directory into your Xcode project.

To import the Amazon Mobile SDK for iOS Objective-C into your project by explicitly downloading Amazon Mobile SDK or using Carthage, follow the instructions in the README.md file. Be sure to use only one of these options to import the Amazon Mobile SDK.

Import the API client class header file to make the API client class callable in the app:

#import "SIMPLE_CALCSimpleCalc.h"

The #import statement also imports SIMPLE_CALCInput.h and SIMPLE_CALCResult.h for the two model classes.

Instantiate the API client class:

SIMPLE_CALCSimpleCalcClient *apiInstance = [SIMPLE_CALCSimpleCalcClient defaultClient];

To use Amazon Cognito with the API, set the defaultServiceConfiguration property on the default AWSServiceManager object, as shown in the following, before calling the defaultClient method to create the API client object (shown in the preceding example):

AWSCognitoCredentialsProvider *creds = [[AWSCognitoCredentialsProvider alloc] initWithRegionType:AWSRegionUSEast1 identityPoolId:your_cognito_pool_id];
AWSServiceConfiguration *configuration = [[AWSServiceConfiguration alloc] initWithRegion:AWSRegionUSEast1 credentialsProvider:creds];
AWSServiceManager.defaultServiceManager.defaultServiceConfiguration = configuration;

Call the GET /?a=1&b=2&op=+ method to perform 1+2:

[[apiInstance rootGet: @"+" a:@"1" b:@"2"] continueWithBlock:^id _Nullable(AWSTask * _Nonnull task) {
    _textField1.text = [self handleApiResponse:task];
    return nil;
}];

where the helper function handleApiResponse:task formats the result as a string to be displayed in a text field (_textField1).

- (NSString *)handleApiResponse:(AWSTask *)task {
    if (task.error != nil) {
        return [NSString stringWithFormat: @"Error: %@", task.error.description];
    } else if (task.result != nil && [task.result isKindOfClass:[SIMPLE_CALCResult class]]) {
        return [NSString stringWithFormat:@"%@ %@ %@ = %@\n",task.result.input.a, task.result.input.op, task.result.input.b, task.result.output.c];
    }
    return nil;
}

The resulting display is 1 + 2 = 3.

Call the POST / with a payload to perform 1-2:

SIMPLE_CALCInput *input = [[SIMPLE_CALCInput alloc] init];
    input.a = [NSNumber numberWithInt:1];
    input.b = [NSNumber numberWithInt:2];
    input.op = @"-";
    [[apiInstance rootPost:input] continueWithBlock:^id _Nullable(AWSTask * _Nonnull task) {
        _textField2.text = [self handleApiResponse:task];
        return nil;
    }];

The resulting display is 1 - 2 = -1.

Call the GET /{a}/{b}/{op} to perform 1/2:

[[apiInstance aBOpGet:@"1" b:@"2" op:@"div"] continueWithBlock:^id _Nullable(AWSTask * _Nonnull task) {
    _textField3.text = [self handleApiResponse:task];
    return nil;
}];

The resulting display is 1 div 2 = 0.5. Here, div is used in place of / because the simple Lambda function in the backend does not handle URL encoded path variables.

Extract the contents of the API Gateway-generated .zip file you downloaded earlier. Using the SimpleCalc API, you may want to rename the unzipped SDK folder to something like sdk_swift_simple_calc. In this SDK folder there is a README.md file and a Podfile file. The README.md file contains the instructions to install and use the SDK. This tutorial provides details about these instructions. The installation leverages CocoaPods to import required Amazon Mobile SDK components. You must update the Podfile to import the SDKs into your Swift app's Xcode project. The unarchived SDK folder also contains a generated-src folder that contains the source code of the generated SDK of your API.

Launch Xcode and create a new iOS Swift project. Make a note of the project's target. You will need to set it in the Podfile.

To import the required Amazon Mobile SDK components into the Xcode project by using CocoaPods, do the following:

1. If it is not installed, install CocoaPods by running the following command in a terminal window:

   sudo gem install cocoapods
   pod setup

2. Copy the Podfile file from the extracted SDK folder into the same directory containing your Xcode project file. Replace the following block:

   target '<YourXcodeTarget>' do
       pod 'AWSAPIGateway', '~> 2.4.7'
   end

   with your project's target name as shown:

   target 'app_swift_simple_calc' do
       pod 'AWSAPIGateway', '~> 2.4.7'
   end

   If your Xcode project already contains a Podfile with the correct target, you can simply add the following line of code to the do ... end loop:

   pod 'AWSAPIGateway', '~> 2.4.7'

3. Open a terminal window and run the following command in the app directory:

   pod install

   This installs the API Gateway component and any dependent Amazon Mobile SDK components into the app's project.

4. Close the Xcode project and then open the *.xcworkspace file to relaunch Xcode.

5. Add all of the SDK's header files (.h) and Swift source code files (.swift) from the extracted generated-src directory to your Xcode project.

6. To enable calling the Objective-C libraries of the Amazon Mobile SDK from your Swift code project, set the Bridging_Header.h file path on the Objective-C Bridging Header property under the Swift Compiler - General setting of your Xcode project configuration:

   Tip

   You can type bridging in the search box of Xcode to locate the Objective-C Bridging Header property.

7. Build the Xcode project to verify that it is properly configured before proceeding further. If your Xcode uses a more recent version of Swift than the one supported for the Amazon Mobile SDK, you will get Swift compiler errors. In this case, set the Use Legacy Swift Language Version property to Yes under the Swift Compiler - Version setting:

To import the Amazon Mobile SDK for iOS in Swift into your project by explicitly downloading the Amazon Mobile SDK or using Carthage, follow the instructions in the README.md file that comes with the SDK package. Be sure to use only one of these options to import the Amazon Mobile SDK.

Instantiate the API client class:

let client = SIMPLE_CALCSimpleCalcClient.default()

To use Amazon Cognito with the API, set a default Amazon service configuration (shown following) before getting the default method (shown previously):

let credentialsProvider = AWSCognitoCredentialsProvider(regionType: AWSRegionType.USEast1, identityPoolId: "my_pool_id")        
let configuration = AWSServiceConfiguration(region: AWSRegionType.USEast1, credentialsProvider: credentialsProvider)        
AWSServiceManager.defaultServiceManager().defaultServiceConfiguration = configuration

Call the GET /?a=1&b=2&op=+ method to perform 1+2:

client.rootGet("+", a: "1", b:"2").continueWithBlock {(task: AWSTask) -> AnyObject? in
    self.showResult(task)
    return nil
}

where the helper function self.showResult(task) prints the result or error to the console; for example:

func showResult(task: AWSTask) {
    if let error = task.error {
        print("Error: \(error)")
    } else if let result = task.result {
        if result is SIMPLE_CALCResult {
            let res = result as! SIMPLE_CALCResult
            print(String(format:"%@ %@ %@ = %@", res.input!.a!, res.input!.op!, res.input!.b!, res.output!.c!))
        } else if result is NSDictionary {
            let res = result as! NSDictionary
            print("NSDictionary: \(res)")
        }
    }
}

In a production app, you can display the result or error in a text field. The resulting display is 1 + 2 = 3.

Call the POST / with a payload to perform 1-2:

let body = SIMPLE_CALCInput()
body.a=1
body.b=2
body.op="-"
client.rootPost(body).continueWithBlock {(task: AWSTask) -> AnyObject? in
    self.showResult(task)
    return nil
}

The resultant display is 1 - 2 = -1.

Call the GET /{a}/{b}/{op} to perform 1/2:

client.aBOpGet("1", b:"2", op:"div").continueWithBlock {(task: AWSTask) -> AnyObject? in
    self.showResult(task)
    return nil
}

The resulting display is 1 div 2 = 0.5. Here, div is used in place of / because the simple Lambda function in the backend does not handle URL encoded path variables.