Passing NSArray containing NSDictionary objects to Javascript function

Question

I have a requirement wherein I have huge set of information in a NSArray which contains NSDictionary objects. Now I have to pass them into a javascript function through a webview using:

- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script

My questions are:

How do I prepare my arguments at the caller end so that Javascript understands it?
How do I receive them in Javascript? Basically, what should be the function signature and how do I read the key-value pairs of dictionary objects of the array inside java function?

I basically do not have enough experience when it comes to Javascript, so forgive me if this question is too abstract, I hope that my question is clear though!

Edit: I came across a thread which states that passing NSDictionary objects to javascript functions is not possible. So, how can we achieve it?

Thanks & Regards, Raj

Jens Ayton · Accepted Answer · 2011-04-19 07:05:50Z

2

Since you can only provide a string to -stringByEvaluatingJavaScriptFromString:, you need to serialize your parameters. The simplest way would be to convert it to JSON using one of the various Cocoa JSON libraries. This can then be inserted in your code as a JavaScript literal. Something like:

NSString *json = [serialize JSON here];
NSString *scriptString = [NSString stringWithFormat:@"doSomething(%@)", json];

In the JSON, the NSDictionaries will be represented as JavaScript Objects, so you’d access their members as array[5].someKey(or array[5]["some key"]).

answered Apr 19, 2011 at 7:05

Jens Ayton

14.5k3 gold badges37 silver badges47 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Raj Pawan Gumdal Over a year ago

Perfect, thanks! Well, one more thing, what exactly is a JavaScrip object?

Alex Gray · Accepted Answer · 2011-09-17 22:55:19Z

You could also rip'em'apart and string 'em back together, like it looks this guys is doing....

function stringToNSString(str) {
  return ['@"',str,'"'].join('');
}
function numberToNSNumber(num) {
  return ['[NSNumber numberWithLong:',num,']'].join('');
}
function booleanToNSNumber(bool) {
  return ['[NSNumber numberWithBool:',(bool ? 'YES' : 'NO'),']'].join('');
}

function nullToNSNull(){
  return '[NSNull null]';
}

function arrayToNSArray(array){
  var lines = _(array).map(function(value){
    var convertedValue;
    if (_(value).isString()) {
      convertedValue = stringToNSString(value);
    } else if (_(value).isNumber()) {
      convertedValue = numberToNSNumber(value);
    } else if (_(value).isBoolean()) {
      convertedValue = booleanToNSNumber(value);
    } else if (_(value).isNull()) {
      convertedValue = nullToNSNull();
    } else if  (_(value).isArray()) {
      convertedValue = arrayToNSArray(value);
    } else if  (typeof value === 'object') {
      convertedValue = objectToNSDictionary(value);
    }
    return convertedValue;
  }).map(function(value){
    return value + ', ';
  });
  lines.unshift('[NSArray arrayWithObjects:');
  lines.push('nil]');
  return lines.join('');
}
function objectToNSDictionary(obj){
  var lines = _(obj).map(function(value,key){
    var convertedValue;
    if (_(value).isString()) {
      convertedValue = stringToNSString(value);
    } else if (_(value).isNumber()) {
      convertedValue = numberToNSNumber(value);
    } else if (_(value).isBoolean()) {
      convertedValue = booleanToNSNumber(value);
    } else if (_(value).isNull()) {
      convertedValue = nullToNSNull();
    } else if  (_(value).isArray()) {
      convertedValue = arrayToNSArray(value);
    } else if  (typeof value === 'object') {
      convertedValue = objectToNSDictionary(value);
    }
    return [convertedValue,stringToNSString(key)];
  }).map(function(valueKey){
    valueKey.push('');
    return valueKey.join(',');
  });
  lines.unshift('[NSDictionary dictionaryWithObjectsAndKeys:');
  lines.push('nil]');
  return lines.join('\n');
}

Alex Gray · Accepted Answer · 2012-02-14 16:14:40Z

I'm a LOT smarter now... ☺ and I think - possibly, maybe... that this (JSONKit on GitHub) is a better solution.... JSONKit provides the following primitive types mapped to the following Objective-C Foundation classes:

╭───────────────┬─────────────────────╮
│  JSON         │  Objective -C       │
├───────────────┼─────────────────────┤
│  true|false   │  NSNull             │
├───────────────┼─────────────────────┤
│  Number       │  NSNumber           │   
├───────────────┼─────────────────────┤
│  String       │  NSString           │
├───────────────┼─────────────────────┤
│  Array        │  NSArray            │
├───────────────┼─────────────────────┤
│  Object       │  NSDictionary       │
╰───────────────┴─────────────────────╯

Objects are Associative Arrays, Key / Value Hash Tables, Maps, or Dictionaries, etc.

JSONKit uses Core Foundation, internally, and it is assumed that Core Foundation ≡ Foundation for every equivalent base type, i.e. CFString ≡ NSString. Also to note, they say it is not ARC-safe.

Collectives™ on Stack Overflow

Passing NSArray containing NSDictionary objects to Javascript function

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related