使用WKWebView Objective C在AngularJS中进行表单发布

基本上我对AngularJS不太了解。我的任务是在WKWebView中加载网页。在该页面中，我必须预先填写用户名和密码，然后使用JavaScript以编程方式单击“登录”按钮。我已经使用JavaScript填充了用户名和密码字段。但是问题是当我通过执行javascript单击“登录”按钮时，它没有与服务器共享任何内容。这是我的表格：

<div class="container ng-scope" ng-controller="LogonController">
<div class="panel panel-default center">
  <div class="panel-heading titletext" id="logo">
     <img src="images\black.png">
  </div>
  <div class="panel-body">
     <!-- ngRepeat: alert in alerts -->
     <form class="form-horizontal center ng-pristine ng-valid" ng-submit="submitCredentials()">
        <div class="control-group">
           <label class="control-label" for="userId">User ID:</label>
           <div class="controls">
              <input type="text" id="useremail" ng-model="userId" autofocus="autofocus" class="ng-pristine ng-untouched ng-valid">
           </div>
        </div>
        <div class="control-group">
           <label class="control-label" for="inputPassword">Password:</label>
           <div class="controls">
              <input type="password" id="userpassword" ng-model="password" class="ng-pristine ng-untouched ng-valid">
           </div>
        </div>
        <div style="margin-top:5px"></div>
        <div class="control-group">
           <div class="controls">
              <button type="submit" class="btn btn-default center"><img src="images/login2.png"> Sign in</button>
           </div>
        </div>
     </form>
  </div>

在iOS方面，我编写了以下代码来执行Javascript：

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
NSLog(@"didFinishNavigation");


dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC),dispatch_get_main_queue(), ^{
    //NSLog(@"Function Called");
    
    NSString *email = @"test";
    NSString *password = @"test";
    
    NSString *fillUser = [NSString stringWithFormat:@"document.getElementById('useremail').value='%@';", [email stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
    NSString *fillPassword = [NSString stringWithFormat:@"document.getElementById('userpassword').value='%@';", [password stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
    
    NSString *resultStringUser = [self stringByEvaluatingJavaScriptFromString:fillUser];
    NSString *resultStringPassword = [self stringByEvaluatingJavaScriptFromString:fillPassword];
    
    //NSLog(@"Result String For User is: %@ and Password: %@", resultStringUser, resultStringPassword);
    
});

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 15 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
    
    NSString *submitFunction = [NSString stringWithFormat:@"document.getElementsByClassName('btn btn-default center')[0].click();"];
    NSString *resultStringSubmit = [self stringByEvaluatingJavaScriptFromString:submitFunction];
    //NSLog(@"Result String for Submit is: %@", resultStringSubmit);
});
}

这是我的stringByEvaluatingJavaScriptFromString方法：

- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script {
__block NSString *resultString = nil;
__block BOOL finished = NO;

[self.webView evaluateJavaScript:script completionHandler:^(id result, NSError *error) {
    if (error == nil) {
        if (result != nil) {
            resultString = [NSString stringWithFormat:@"%@", result];
        }
    } else {
        NSLog(@"evaluateJavaScript error : %@", error.localizedDescription);
    }
    finished = YES;
}];

while (!finished)
{
    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}

return resultString;
}

由于进行了这些验证，因此用户名和密码为空白，形式为“ ng-pristine ng-untouched ng-valid”。只要用iPhone的键盘输入用户名和密码，它就可以通过javascript调用登录以进行按钮单击。在使用JS执行的JavaScript提交表单之前，有什么方法可以在表单中调用或验证“ ng-pristine ng-untouched ng-valid”？

注意：我无权更改服务器中的JS。无论我要做什么，都必须来自iOS。

谢谢