Understanding UIWebView Session Expiration

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In this article, we will delve into the world of UIWebView and explore how to prevent session expiration. We will take a closer look at the underlying mechanics and discuss possible solutions.

What is UIWebView?

UIWebView is a web view component in iOS that allows you to display web content within your app. It’s often used for loading external URLs or displaying web-based content. However, managing sessions and cookies can be challenging due to its sandboxed nature.

The Problem of Session Expiration

When using UIWebView, the default behavior is to expire sessions after a certain period. This means that if you try to access a webpage with a session cookie, it will not be recognized by the web view, resulting in an infinite loop of redirects and eventually leading to the app crashing.

The Solution: Storing and Restoring Cookies

The solution lies in storing and restoring cookies using NSKeyedArchiver and NSUserDefaults. By saving the cookies before loading the webpage and restoring them when needed, we can prevent session expiration.

Saving Cookies

To save cookies, you need to store them in a data object using NSKeyedArchiver. First, create an array of cookies from the shared HTTP cookie storage:

NSArray *cookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies];

Then, use NSKeyedArchiver to serialize the cookies into a data object:

NSData *cookiesData = [NSKeyedArchiver archivedDataWithRootObject:cookies];

Store the serialized data in NSUserDefaults using the key "cookies":

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:cookiesData forKey:@"cookies"];
[defaults synchronize];

Restoring Cookies

To restore cookies, retrieve the serialized data from NSUserDefaults, deserialize it into an array of cookies using NSKeyedUnarchiver:

NSArray *cookies = [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"cookies"]];

Then, update the properties of each cookie to include the expiration date. You can use the following code snippet as a starting point:

for (NSHTTPCookie *cookie in cookies)
{
    NSMutableDictionary *newProperties = [[NSMutableDictionary alloc]initWithDictionary:cookie.properties];
    NSDate *date = [newProperties objectForKey:NSHTTPCookieExpires];
    if(date == nil)
        [newProperties setObject:[[NSDate date] dateByAddingTimeInterval:100*12*30*60*60] forKey:NSHTTPCookieExpires];
    else
        [newProperties setObject:[[NSDate date] dateByAddingTimeInterval:100*12*30*60*60] forKey:NSHTTPCookieExpires];
    NSHTTPCookie *newCookie = [NSHTTPCookie cookieWithProperties:newProperties];
    [cookieStorage setCookie: newCookie];
}

Implementing Cookie Storage and Restoring

To implement the solution, follow these steps:

Step 1: Add Cookie Storage to loadCookies Method

First, add the following code snippet to your loadCookies method to store cookies in NSUserDefaults:

- (void)saveCookies {
   NSData *cookiesData = [NSKeyedArchiver archivedDataWithRootObject:[NSHTTPCookieStorage sharedHTTPCookieStorage].cookies];
   NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
   [defaults setObject:cookiesData forKey:@"cookies"];
   [defaults synchronize];
}

Step 2: Call saveCookies Method

Call the saveCookies method in your viewDidLoad or any other relevant initialization method to store cookies:

[self saveCookies];

Step 3: Modify addCookies Method

Modify the addCookies method to restore cookies before loading the webpage:

- (NSURLRequest*)addCookies:(NSArray *)cookies forRequest:(NSURLRequest *)request {
    // ...
    NSArray *storedCookies = [[NSUserDefaults standardUserDefaults] objectForKey:@"cookies"];
    if (storedCookies) {
        [self loadCookies];
    }
    return [self addCookies:cookies forRequest:request];
}

Step 4: Call loadCookies Method

Call the loadCookies method in your addCookies method to restore cookies before loading the webpage:

- (NSURLRequest*)addCookies:(NSArray *)cookies forRequest:(NSURLRequest *)request {
    // ...
    [self loadCookies];
    return [self addCookies:cookies forRequest:request];
}

By following these steps, you can prevent session expiration in your UIWebView and ensure that cookies are properly stored and restored.

Last modified on 2023-07-07