WebView is causing huge memory leak - iphone

Question

I have a table view controller in my app. Each cell is the name of a website. When a cell is hit a web view controller is created, passed a url and pushed to the view.
Pretty standard right?
If I go in and out of a web view enough times I begin to get memory warnings until the app crashes.
I can't see anywhere in my implementation where I'm not releasing anything properly. Is there some webview specific best practices or important delegate methods I might have left out?
This is driving me crazy because there is very little code involved and yet I still can't seem to find the problem.
Could somebody help me discover what is causing this memory problem or prehaps refer me to an article or tutorial so I can see how to do this properly?
Table View Controller
#implementation LinkListViewController
#synthesize linksArray;
#synthesize wvcontroller;
#pragma mark -
#pragma mark Initialization
- (void)loadView {
[super loadView];
table = [[UITableViewController alloc] initWithStyle:UITableViewStylePlain];
[self pushViewController:table animated:YES];
table.tableView.delegate = self;
table.tableView.dataSource = self;
table.title = #"Links"; // Tab Bar Title
[self.view addSubview:table.view];
}
-(id) initWithTabBar {
if ([self init]) {
self.tabBarItem.image = [UIImage imageNamed:#"events.png"];
}
return self;
}
#pragma mark -
#pragma mark Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [linksArray count];;
}
#define LABEL_TAG 7777
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
LinkData *ld;
ld=[linksArray objectAtIndex:indexPath.row];
static NSString *CellIdentifier = #"Cell";
UILabel *label = nil;
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
CGRect frame;
frame.origin.x = 0;
frame.origin.y = 10;
frame.size.width = 100;
frame.size.height = 30;
frame.origin.x = 0;
frame.size.width =290;
label = [[[UILabel alloc] initWithFrame:frame] autorelease];
label.tag = LABEL_TAG;
[cell.contentView addSubview:label];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
} else {
label = (UILabel *) [cell.contentView viewWithTag:LABEL_TAG];
}
label.text = [ld.linkname copy];
label.textColor=[UIColor blackColor];
return cell;
}
#pragma mark -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
LinkData *ld=[linksArray objectAtIndex:indexPath.row];
if ([ld.linktype isEqualToString:#"webpage"]) {
if (wvcontroller) {
[wvcontroller release];
wvcontroller=nil;
}
wvcontroller= [[WebViewController alloc]initWithPath:ld.linkurl];
wvcontroller.title=ld.linkname;
[table.navigationController pushViewController:wvcontroller animated:YES];
}
}
Web View Controller
#import "WebViewController.h"
#implementation WebViewController
#synthesize webView;
#synthesize path;
#synthesize showsync;
#synthesize activity;
-(id)initWithPath:(NSString *)thepath
{
if ( [self init]) {
self.path= [thepath copy];
self.view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
[self.view setBackgroundColor:[UIColor blackColor]];
[self loadView];
}
return self;
}
- (void)loadView {
//Create a URL object.
webView = [[UIWebView alloc] initWithFrame:self.view.frame];
webView.autoresizesSubviews = YES;
webView.autoresizingMask=(UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth);
//set the web view delegates for the web view to be itself
self.webView.scalesPageToFit = YES;
self.webView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
self.webView.delegate = self;
//Create a URL object.
NSURL *url = [NSURL URLWithString:path];
//URL Requst Object
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
//add the web view to the content view
[self.view addSubview:webView];
//load the URL into the web view.
[webView loadRequest:requestObj];
//[webView release], webView = nil;
activity = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
activity.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
activity.center = self.view.center;
[self.view addSubview: activity];
}
/*
If you need to do additional setup after loading the view, override viewDidLoad. */
- (void)viewDidLoad {
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.webView;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (void)dealloc {
[webView release];
[activity release];
webView=nil;
[path release];
[super dealloc];
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc. that aren't in use.
}
- (void)viewDidUnload {
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)webViewDidStartLoad:(UIWebView *)webView {
[activity startAnimating];
}
- (void)webViewDidFinishLoad:(UIWebView *)webView {
[activity stopAnimating];
}

Answer 1

You still hold an extra reference to self.view at the end of initWithPath which should be released.
A bit more explanation: [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] gives you a UIView with a retain count of 1 (since you have just allocated it). Assigning it to self.view bumps its retain count by 1, so it is 2 at the moment. When your controller is deallocated, it takes care of decreasing the retain count of the object in self.view, but the count is still 1, so it never gets deallocated. You should do this:
UIView* myView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
self.view = myView;
[myView release];

Answer 2

One way to avoid UIWebView memory problems is to create only one webview one time, and reuse it for the whole life of the application. That is, not release it but reuse it.