为了明确这一点，我将拆分我的问题。

目标:

执行一些 Javascript 后检查页面上的 a 元素 ONCE;但如果它不正确，我希望能够通过按下按钮重新检查它。

我尝试过的:

        -(IBAction)signin {

    [passwordTF resignFirstResponder];
    [usernameTF resignFirstResponder];

    //create js strings
    NSString *loadUsernameJS = [NSString stringWithFormat:@"var field = document.getElementById('login-form-username'); field.value='%@';", username];

    NSString *loadPasswordJS = [NSString stringWithFormat:@"var field = document.getElementById('login-form-password'); field.value='%@';", password];

    //autofill the form
    [mainWebView stringByEvaluatingJavaScriptFromString:loadUsernameJS];
    [mainWebView stringByEvaluatingJavaScriptFromString:loadPasswordJS];

    //auto login
    [mainWebView stringByEvaluatingJavaScriptFromString:@"document.getElementById('submit-login').click();"];


}

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

    NSLog(@"webViewDidiFinishLoad called");

    if (shouldVerify == YES) {

        NSLog(@"webViewDidiFinishLoad - shouldVerify YES");

        NSString *failedLogin = [mainWebView stringByEvaluatingJavaScriptFromString: @"document.getElementById('login-msg')"];

        if ([failedLogin isEqualToString:@"Failed login"]) {

            NSLog(@"webViewDidiFinishLoad - shouldVerify YES - failed");

            UIAlertView *WCE = [[UIAlertView alloc] initWithTitle:@"Wrong Credentials" message:@"The username or password you entered is incorrect please try again." delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
            [WCE show];

            [keychainItem resetKeychainItem];

            password = [keychainItem objectForKey:(__bridge id)(kSecValueData)];
            username = [keychainItem objectForKey:(__bridge id)(kSecAttrAccount)];

            [usernameTF setText:username];
            [passwordTF setText:password];


        } else {

            NSLog(@"webViewDidiFinishLoad - shouldVerify YES - success");

            ViewController *viewController = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"ViewController"];

            UINavigationController *navBar=[[UINavigationController alloc]initWithRootViewController:viewController];

            navBar.navigationBarHidden = YES;

            [self presentViewController:navBar animated:YES completion:nil];
        }

        shouldVerify = NO;
    }
}

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

    if (navigationType == UIWebViewNavigationTypeOther) {

        NSLog(@"shouldStartLoadWithRequest - shouldVerify YES");

        shouldVerify = YES;

    } else {

        NSLog(@"shouldStartLoadWithRequest - shouldVerify NO");

        shouldVerify = NO;

    }

    return YES;
}

问题:

出于某种原因:

if ([failedLogin isEqualToString:@"Failed login"]) {

            NSLog(@"webViewDidiFinishLoad - shouldVerify YES - failed");

            UIAlertView *WCE = [[UIAlertView alloc] initWithTitle:@"Wrong Credentials" message:@"The username or password you entered is incorrect please try again." delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
            [WCE show];


        } else {

            NSLog(@"webViewDidiFinishLoad - shouldVerify YES - success");

        }

if 语句总是返回 false 并且

  NSLog(@"webViewDidiFinishLoad - shouldVerify YES - success");

在不应该打印的时候打印出来，failedLogin 等于@"Failed Login"。如果我删除 else 语句，它总是会在 if 语句为真时将 if 语句验证为错误的登录凭据，这就是为什么我认为我在处理它之前先检查它。

我的猜测:

当 webView 尚未完成执行 javascript 和/或在单击按钮后重新加载网页时，我正在运行此 if 语句。

资源:

我不知道这有什么帮助，但我正在使用的网站是:tapgram.com/login

此处提供完整的当前代码:http://pastebin.com/dnCn62FP 对于完整的项目代码，请发表评论，我会添加链接。

最佳答案

错误在 JavaScript 中。

NSString *failedLogin = [mainWebView 
stringByEvaluatingJavaScriptFromString:@"document.getElementById('login-msg')"];

返回 login-msg 元素的完整 HTML 字符串。

所以基本上你是在比较Failed login与 <h4 id=​"login-msg" style=​"color:​red;​">​Failed login​</h4> .

JavaScript 应该是这样的 document.getElementById('login-msg').innerText如果登录确实失败，它将返回 Failed login。

关于javascript - 自动填充后在 UIWebView 中执行 Javascript 后验证标签的长度，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20504389/