In Part 1 of this series I showed how to exchange basic types such as Number, int, uint, String, and Boolean data between ActionScript 3 and C (or C++, C#, or Objective-C) for native extensions on iOS. In this article, I illustrate the same technique using arrays and Vector objects.

If you haven't done so already, I recommend reading Part 1 before proceeding with this article.

Exchanging arrays between ActionScript 3 and C

This example implements a native language reverseArray() function, which reverses the elements in an ActionScript Array object. For example, if it is provided [1,2,3] as an array it returns [3,2,1] .

Here is the ActionScript 3 code:

        public function reverseArray(array:Array):Array{
    var ret:Array= context.call("reverseArray",array) as Array;
    return ret;
}

    

The C code is a bit more complex than the code for basic data types. It performs the following steps:

Get an array from the arguments
Find the array's length
Create a new ActionScript 3 Array instance in C
Loop through the original array and fill in the new array
Return the new array

Here is the code:

        FREObject reverseArray(FREContext ctx, void* funcData, uint32_t argc, FREObject argv[]){
    FREObject arr = argv[0]; // array
    uint32_t arr_len; // array length
 
    FREGetArrayLength(arr, &arr_len);
 
    FREObject populatedArray = NULL;
    // Create a new AS3 Array, pass 0 arguments to the constructor (and no arguments values = NULL)
    FRENewObject((const uint8_t*)"Array", 0, NULL, &populatedArray, nil);
 
    FRESetArrayLength(populatedArray, arr_len);
 
    NSLog(@"Going through the array: %d",arr_len);
 
    int32_t j = 0;
    for(int32_t i=arr_len-1; i>=0;i--){
 
        // get an element at index
        FREObject element;
        FREGetArrayElementAt(arr, i, &element);
 
        // OPTIONAL: get an int value out of the element
        int32_t value;
        FREGetObjectAsInt32(element, &value);
 
        // log index and value
        NSLog(@"Get item %d: %d",i,value);
 
        NSLog(@"Set item %d: %d",j,value);
        FRESetArrayElementAt(populatedArray, j, element);
        j++;
    }
 
    return populatedArray;
}

    

Exchanging Vector objects between ActionScript 3 and C

The implementation for exchanging Vector variables is almost identical to the implementation for Array variables. The key difference is in the creation of the Vector object. For a Vector with integer elements, that will look like this:

FRENewObject((const uint8_t*)"Vector.<int>", 0, NULL, &populatedArray, nil);

Here is the ActionScript 3 code for reverseVector , which implements the same functionality as reverseArray :

        public function reverseVector(vector:Vector.<int>):Vector.<int>{
    var ret:Vector.<int>= context.call("reverseVector",vector) as Vector.<int>;
    return ret;
}

    

Here is the C code:

        FREObject reverseVector(FREContext ctx, void* funcData, uint32_t argc, FREObject argv[]){
 
    FREObject arr = argv[0]; // array
    uint32_t arr_len; // array length
 
    FREGetArrayLength(arr, &arr_len);
 
    FREObject populatedVector = NULL;
    // Create a new AS3 Vector, pass 0 arguments to the constructor (and no arguments values = NULL)
    FRENewObject((const uint8_t*)"Vector.<int>", 0, NULL, &populatedVector, nil);
 
    FRESetArrayLength(populatedVector, arr_len);
 
    NSLog(@"Going through the vector: %d",arr_len);
 
    int32_t j = 0;
    for(int32_t i=arr_len-1; i>=0;i--){
 
        // get an element at index
        FREObject element;
        FREGetArrayElementAt(arr, i, &element);
 
        // OPTIONAL: get an int value out of the element
        int32_t value;
        FREGetObjectAsInt32(element, &value);
 
        // log index and value
        NSLog(@"Get item %d: %d",i,value);
 
        NSLog(@"Set item %d: %d",j,value);
        FRESetArrayElementAt(populatedVector, j, element);
        j++;
    }
 
    return populatedVector;   
}

    

Where to go from here

As I mentioned in Part 1, a good starting point for learning more about native extensions is the Native C API Reference for Adobe AIR extensions.

Part 3 of this series (to come soon) covers exchanging custom objects between ActionScript 3 and native extensions.

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. Permissions beyond the scope of this license, pertaining to the examples of code included within this work are available at Adobe.

Transferring data with AIR native extensions for iOS – Part 2: Exchanging Vector and Array objects between ActionScript 3 and C, C++, or Objective-C

by Tom Krcha

Content

Created

Page tools

Requirements

Prerequisite knowledge

User level

Required products

Sample files

Exchanging arrays between ActionScript 3 and C

Exchanging Vector objects between ActionScript 3 and C

Where to go from here

More Like This

Products

Download

Support & Learning

Buy

Company