Objective-C

Call a JavaScript Function Returning an Integer

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Demonstrates how to call a JavaScript function that returns an integer. Objective-C

#import <CkoStringBuilder.h>
#import <CkoJs.h>
#import <CkoJsonObject.h>

BOOL success = NO;

// ----------------------------------------------------------------------------------
// The Javascript function called in this example is shown at the bottom of this page.
// -----------------------------------------------------------------------------------

// In this example, we'll load the Javascript function definition from a file.
// It doesn't need to come from a file.  It could just as easily be loaded from a string.
CkoStringBuilder *sbScript = [[CkoStringBuilder alloc] init];
success = [sbScript LoadFile: @"js_call_function.js" charset: @"utf-8"];
if (success == NO) {
    NSLog(@"%@",sbScript.LastErrorText);
    return;
}

// Note: Each instance of a Chilkat Js object automatically establishes
// its own internal runtime and context.  Applications do not need to explicitly create
// the JavaScript runtime or context.
CkoJs *js = [[CkoJs alloc] init];

CkoJsonObject *result = [[CkoJsonObject alloc] init];
result.EmitCompact = NO;

// Call Eval to add the function (shown at the bottom of this page) to the context's global object
success = [js Eval: sbScript result: result];
if (success == NO) {
    // Examine the result for an exception.
    NSLog(@"%@",[result Emit]);

    // Also examine the LastErrorText.
    NSLog(@"%@",js.LastErrorText);
    return;
}

NSLog(@"%@",[result Emit]);

// The expected output is "undefined":

// {
//   "type": "undefined",
//   "value": "undefined"
// }

//    When Eval processes a script containing only a function declaration,
//    it successfully performs the action (the function becomes defined).
//    However, since the script consists of a statement that produces no value,
//    the script's overall completion value is empty. In JavaScript, the
//    absence of a value is represented by `undefined`.
// 
//    Therefore, the Eval call returns `undefined`.

// ------------------------------------------------------------------------------
// Call the function calculateScore("Player1", 10, 20)

CkoJsonObject *funcCall = [[CkoJsonObject alloc] init];

// Create JSON defining the function call:

// {
//   "name": "calculateScore",
//   "args": [ "Player1", 10, 20 ]
// }

[funcCall UpdateString: @"name" value: @"calculateScore"];
[funcCall UpdateString: @"args[0]" value: @"Player1"];
[funcCall UpdateInt: @"args[1]" value: [NSNumber numberWithInt: 10]];
[funcCall UpdateInt: @"args[2]" value: [NSNumber numberWithInt: 20]];

funcCall.EmitCompact = NO;
NSLog(@"%@",[funcCall Emit]);

success = [js CallFunction: funcCall result: result];
if (success == NO) {
    // Examine the result for an exception.
    NSLog(@"%@",[result Emit]);

    // Also examine the LastErrorText.
    NSLog(@"%@",js.LastErrorText);
    return;
}

NSLog(@"%@",[result Emit]);

// Output:

// {
//   "type": "int",
//   "value": 37
// }

int retval = [[result IntOf: @"value"] intValue];
NSLog(@"%@%d",@"retval = ",retval);