Is it possible for a UIWebView to save and autofill previously entered form values (e.g., username & password)?

Question

I'm building an iPhone app that is just a UIWebView of an existing mobile site that has a form-based login. When I login to the mobile site on iPhone Safari, I'm prompted to save my username/password, and it's then autofilled when I go back to the site later.

I'd like to enable the same functionality in the UIWebView, but for the life of me, I can't figure out how to do it. Any ideas?

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Solution

Following Michael's basic model (see accepted answer), I was able to get this done. Here's what I did:

SETTING DATA

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType; {

    //save form data
    if(navigationType == UIWebViewNavigationTypeFormSubmitted) {

        //grab the data from the page
        NSString *username = [self.webView stringByEvaluatingJavaScriptFromString: @"document.myForm.username.value"];
        NSString *password = [self.webView stringByEvaluatingJavaScriptFromString: @"document.myForm.password.value"];

        //store values locally
        [[NSUserDefaults standardUserDefaults] setObject:username forKey:@"username"];
        [SFHFKeychainUtils storeUsername:username andPassword:password forServiceName:@"MyService" updateExisting:YES error:nil];

    }    

}

GETTING DATA

- (void)webViewDidFinishLoad:(UIWebView *)webView{

    //verify view is on the login page of the site (simplified)
    NSURL *requestURL = [self.webView.request URL];
    if ([requestURL.host isEqualToString:@"www.mydomain.com"]) {

        //check for stored login credentials
        NSString *username = [[NSUserDefaults standardUserDefaults] objectForKey:@"username"];

        if (username.length != 0 ) {

            //create js strings
            NSString *loadUsernameJS = [NSString stringWithFormat:@"document.myForm.username.value ='%@'", username];
            NSString *password = [SFHFKeychainUtils getPasswordForUsername: username andServiceName:@"MyService" error:nil];
            if (password.length == 0 ) password = @"";
            NSString *loadPasswordJS = [NSString stringWithFormat:@"document.myForm.password.value ='%@'", password];

            //autofill the form
            [self.webView stringByEvaluatingJavaScriptFromString: loadUsernameJS];
            [self.webView stringByEvaluatingJavaScriptFromString: loadPasswordJS];

        }
    }   
}

Note that I'm using Buzz Andersen's awesome SFHFKeychainUtils package to store sensitive data to the iOs Keychain.

In order to get SFHFKeychainUtils working, you need to do a few things:

1. Add SFHFKeychainUtils.h and SFHFKeychainUtils.m to your project
2. Add the Security.framework to your project
3. #import <Security/Security.h> and #import "SFHFKeychainUtils.h"

Answer 1

From my looking I don't think there is an easy way to do it. Here is an idea of what might work though:

• create your uiwebview
• create a nsurlrequest
• after your webview delegate page loaded function fires look in the request's http body
• find the form for login (regex for common login forms?)
• retrieve give the user the option to save it and then retrieve later