Memory Leak in Titanium tabbed iPhone application

Question

this has been giving me a headache for a couple weeks now -- hope somebody can help. I'm building an app for iOs 5.0, using the 2.1.4 SDK in Titanium mobile. My app pulls data from a database, and displays it in a scrollableview using labels and a table. I've noticed that it crashes after a while, and according to instruments, the views within the scrollableView, along with the labels and tableviews, are never released from memory. I use a lot of commonJS, and my code looks someting like this (stripped down):

The ApplicationWindow module, which I call from app.js

function ApplicationWindow(title) {
var self = Ti.UI.createWindow({
    title:title,
    backgroundColor:'white'
});

var button = Ti.UI.createButton({
    height:44,
    width:200,
    title:L('openWindow'),
    top:20
});
self.add(button);

var QuizWindow = require('/ui/common/QuizWindow');

button.addEventListener('click', function() {
    //containingTab attribute must be set by parent tab group on
    //the window for this work
    qw = new QuizWindow({title: 'KCT', backgroundColor: 'white', navBarHidden: true, tabBarHidden: true});
    self.containingTab.open(qw);
});

return self;
};

module.exports = ApplicationWindow;

I then call the QuizWindow module:

function QuizWindow(args){
var instance = Ti.UI.createWindow(args);
var QuestionView = require('/ui/common/QuestionView');

var db = Ti.Database.install("/kct.sqlite","kct");
var q = db.execute("SELECT * FROM questions");

var sv = Ti.UI.createScrollableView({
    bottom: 40
});

while(q.isValidRow()){
    var id = q.fieldByName("qid");
    var question = q.fieldByName("q");
    var set = q.fieldByName("set");
    var info = q.fieldByName("info");

    var v = new QuestionView(id,set,question,info);
    sv.addView(v);
    q.next();
}

q.close();
db.close();

var button = Ti.UI.createButton({
    height:44,
    width:200,
    title:"Close",
    bottom:10
});

button.addEventListener('click', function() {
    instance.close({animation: true});
});

instance.add(sv);
instance.add(button);
return instance;
};
module.exports = QuizWindow;

and this is the QuestionView:

function QuestionView (id,set,question,infolert) {
var qview = Ti.UI.createView({
    top: 0,
    width: 'auto',
    height: 'auto',
    backgroundColor: 'white',
    questionSet: set,
    questionID: id,
    info: infolert,
    isAnswered: false       
});

var qLabel = gui.Header(question);
qLabel.top = 5;
qLabel.left = 10;
qLabel.right = 10;
qLabel.color = "#3B3B3B";
qLabel.font = {fontSize: gui.defaultFontSize+4, fontWeight: 'bold'};

var dcalc = (qLabel.text.length / 30) * ((gui.defaultFontSize+4)*1.2) + 5;

var answView = Ti.UI.createTableView({
    backgroundColor: 'white',
    top: dcalc,
    _parent: qview
});

var changeheight = function(e) {
    var lheight = e.source.rect.height;
    if(lheight && lheight > 10) answView.top = lheight + 5;
    return;
};

qLabel.addEventListener('postlayout', changeheight);


qview.add(qLabel);
qview.add(answView);

return qview;

}
 module.exports = QuestionView;

I originally had some code in there to pull data for the answers from the database, and fill the tableView with that, but I removed it for the sake of brevity. Even without that, nothing gets released. I'm really at a loss here, any advice is appreciated.

Answer 1

You can have a look at my Gist. By using this you can solve out the memory issue to great extend. Just include the class in your project and use it like this.

https://gist.github.com/3898340

var mem = new MemoryClean();
    mem.clean(tableView);
    mem.clean(headerView);
    mem.clean(footerView);
    mem = null;

Here is what i have been using.

function openAppointments(e) {
    var mem = new MemoryClean();
    mem.clean(headerView);
    mem.clean(footerView);
    mem = null;
    win.close();
}

Answer 2

In the end, I solved it. It was this:

var answView = Ti.UI.createTableView({
    (...)
    _parent: qview
});

referencing the view in the answer table kept it, and all its children, from being released. Once I removed that, they get released simply by closing the window. Hope that's useful for someone.