Sketch JSON Parser

main.js

var doc = context.document,
    app = [NSApplication sharedApplication],
    jsonStr = [doc askForUserInput:"Enter the JSON you'd like to use" initialValue:""],
    json;

try {
	json = JSON.parse(jsonStr);
} catch(e){
    [app displayDialog:"Whoops, looks like that's not valid JSON."]
	return;
}

var selectedLayers = context.selection,
	selectedCount = selectedLayers.count(),
	getValByPath = function(path){
		var pieces = path.split('.'),
            currPath = json;
          
        for(var i = 0; i < pieces.length; i++){
            var val = pieces[i];
            if(currPath[val] == undefined){
                return undefined;
            } else {
                currPath = currPath[val];
            }
        }
          
        return currPath;
	};

if(selectedCount == 0) {
    [app displayDialog:"No layers are selected."]
} else {
  	for(var i = 0; i < selectedCount; i++){
    	var layer = selectedLayers[i],
            tagMatch = layer.name().match(/\$([^\s]+)/),
    		tagVal = tagMatch ? tagMatch[1].trim() : '';

    	if(!tagVal) continue;

        switch(layer.class()){
            case MSTextLayer:
                var val = getValByPath(tagVal);
                if(val){
                    layer.setStringValue(String(val));
                    layer.adjustFrameToFit();
                }
                break;
            case MSBitmapLayer:
                log('it\'s an image');
                break;
        }

  	}
}