iOS memory leaks causing crash in changing view controllers - iphone

Question

I have created two view controllers in which there is UIImage animations.Its crashing frequently and showing memory leaks in xcode instrument.
My Controllers Code-
- (void)viewDidLoad {
NSArray *firstArray;
firstArray = [NSArray arrayWithObjects:
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"up0001" ofType:#"png"]],
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"up0002" ofType:#"png"]],
::
::
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"up0035" ofType:#"png"]], nil];
imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];
imgView = UIViewContentModeScaleToFill;
[imgView setAnimationImages:firstArray];
imgView.animationDuration = 1.75;
imgView.animationRepeatCount = 0;
[imgView startAnimating];
[self.view addSubview: imgView];
}
- (void)dealloc {
[super dealloc];
[imgView release];
imgView = nil;
}
And I am changing viewcontrollers as my rootviewcontroller by getting appdelegate object and calling following appdelegate function in my Appdelegate.m(Please suggest any good approach)
- (void)changeRootViewController:(NSString *)controllerName
{
if(self.viewController){
[self.viewController.view removeFromSuperview];
self.viewController=nil;
}
if (controllerName == #"ViewController") {
ViewController *lviewController =[[ViewController alloc] initWithNibName:#"ViewController" bundle:nil];
self.viewController = (RootViewController *)lviewController;
[lviewController release];
lviewController.view = nil;
[self.window setRootViewController:self.viewController]; //LEAKS 100%
} else if (controllerName == #"MainViewController") {
// Use a different VC as roowViewController
MainViewController *lviewController =[[MainViewController alloc] initWithNibName:#"MainViewController" bundle:nil];
self.viewController = (RootViewController *)lviewController;
[lviewController release];
lviewController.view = nil;
[self.window setRootViewController:self.viewController]; //LEAKS 100%
} else if (controllerName == #"SecondViewController") {
// Use a different VC as roowViewController
SecondViewController *lviewController =[[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
self.viewController = (RootViewController *)lviewController;
[lviewController release];
lviewController.view = nil;
[self.window setRootViewController:self.viewController]; //LEAKS 100%
}
[self.window makeKeyAndVisible];
}
And calling this in my respective controlers button pressed as -
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
[appDelegate changeRootViewController:#"ViewController"];
OR
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
[appDelegate changeRootViewController:#"MainViewController"];
I want to manage view controllers from my main controller swapping controllers in and out without Navigationbar.Please help me figure out the best possible approach and avoid leaks as well.

Answer 1

Look at this piece of code:
if (controllerName == #"ViewController") {
ViewController *lviewController =[[ViewController alloc] initWithNibName:#"ViewController" bundle:nil];
self.viewController = (RootViewController *)lviewController;
[lviewController release];
lviewController.view = nil;
[self.window setRootViewController:self.viewController]; //LEAKS 100%
}
When you alloc "lviewController", its retain count is 1;
when you do "self.viewController" as I suppose viewController is a retained property, then lviewController retain count is increased to 2;
then you release it, balancing the previous alloc, and retain count returns to 1;
finally you assign it to rootViewController, which is a retained property, so again lviewController retain count is 2;
finally when you "swap" view controller in your window, the lviewController is released, so it retain count becomes 1. As you can see, it will never be dealloc'd. This means that each time you call this function, you make a leak.

Answer 2

You require to change some of your statement in your code ..
This line have no meaning ..
imgView = UIViewContentModeScaleToFill;
There is a function by using that you have to set the value of the UIImageView property to UIViewContentModeScaleToFill find that in a UIImageView documentation.
[imageView setContentMode:UIViewContentModeScaleToFill];
The same with this...
lviewController.view = nil; //Remove this from your code ..
And finally change the implmentation for the dealloc function and remember [super dealloc]; should be in the last in any implementation of dealloc .
- (void)dealloc {
[imgView release];
imgView = nil;
[super dealloc];
}

Answer 3

The probable leak is due to the code inside "SecondViewController", "MainViewController", "ViewController" classes. And the reason for crash is you are releasing image view after [super dealloc]
try this,
- (void)dealloc {
[imgView release];
imgView = nil;
[super dealloc];
}