Objective-C

Call a JavaScript Function Returning a Boolean

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

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

BOOL success = NO;

//  This is the JavaScript function we'll call:

//  function isEven(number) {
//      return number % 2 === 0;
//  }

CkoStringBuilder *sbScript = [[CkoStringBuilder alloc] init];
[sbScript Append: @"function isEven(number) { return number % 2 === 0; }"];

CkoJs *js = [[CkoJs alloc] init];

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

//  Call Eval to add the function 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;
}

//  ------------------------------------------------------------------------------
//  Call the function isEven(8)

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

//  Create JSON specifying the function name and arguments

//  {
//    "name": "isEven",
//    "args": [ 8 ]
//  }

[funcCall UpdateString: @"name" value: @"isEven"];
[funcCall UpdateInt: @"args[0]" value: [NSNumber numberWithInt: 8]];

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": "bool",
//    "value": true
//  }

BOOL retval = [result BoolOf: @"value"];
NSLog(@"%d",retval);

//  Output:
//  true