您好我正在编写与 Web 服务通信的 iphone 应用程序，所以我有两个文本字段，程序需要读取第一个文本字段的值并发布 Web 服务，然后在 Web 服务响应后它需要编写第二个文本字段。但是在第二个文本字段中它没有写任何东西。它在控制台上打印 null。为什么会变成这样？ 谢谢。

 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
    {
        self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
        if (self) {
            nodeContent = [[NSMutableString alloc]init];
        }
        return self;
    }

- (IBAction)login:(id)sender {

    NSLog(@"PASSWORD text: %@",password.text);

    if ([password.text length]==0) {

        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"WebService" message:@"Supply Data in text field" delegate:nil cancelButtonTitle:nil otherButtonTitles:@"ok",nil];
        [alert show];
        [alert release];
    }
    else {

        NSString *soapFormat = [NSString stringWithFormat:@"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
                                "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n"
                                "<soap:Body>\n"
                                "<CelsiusToFahrenheit xmlns=\"http://tempuri.org/\">\n"
                                "<Celsius>%@</Celsius>\n"
                                "</CelsiusToFahrenheit>\n"
                                "</soap:Body>\n"
                                "</soap:Envelope>\n",password.text];


        NSLog(@"The request format is %@",soapFormat);

        NSURL *locationOfWebService = [NSURL URLWithString:@"http://www.w3schools.com/webservices/tempconvert.asmx"];

        NSLog(@"web url = %@",locationOfWebService);

        NSMutableURLRequest *theRequest = [[NSMutableURLRequest alloc]initWithURL:locationOfWebService];

        NSString *msgLength = [NSString stringWithFormat:@"%d",[soapFormat length]];

        [theRequest addValue:@"text/xml" forHTTPHeaderField:@"Content-Type"];
        [theRequest addValue:@"http://tempuri.org/CelsiusToFahrenheit" forHTTPHeaderField:@"SOAPAction"];
        [theRequest addValue:msgLength forHTTPHeaderField:@"Content-Length"];
        [theRequest setHTTPMethod:@"POST"];
        //the below encoding is used to send data over the net
        [theRequest setHTTPBody:[soapFormat dataUsingEncoding:NSUTF8StringEncoding]];


        NSURLConnection *connect = [[NSURLConnection alloc]initWithRequest:theRequest delegate:self];

        if (connect) {
            webData = [[NSMutableData alloc]init];
            startActivityIndicator;
        }
        else {
            NSLog(@"No Connection established");
        }


      //  [self performSegueWithIdentifier:@"logindevam" sender:self];

    }

}
- (IBAction)sendkeyboard:(id)sender {
    [sender resignFirstResponder];
}

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [webData setLength: 0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [webData appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"ERROR with theConenction");
    [connection release];
    [webData release];
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"DONE. Received Bytes: %d", [webData length]);
    NSString *theXML = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding];
    NSLog(@"%@",theXML);

    xmlParser = [[NSXMLParser alloc]initWithData:webData];
    [xmlParser setDelegate: self];
    //[xmlParser setShouldResolveExternalEntities: YES];
    [xmlParser parse];
    //  
    [connection release];
    //[webData release];
    //[resultTable reloadData];
    stopActivityIndicator;
}


//xml delegates

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict
{

}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    [nodeContent appendString:[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    if ([elementName isEqualToString:@"CelsiusToFahrenheitResult"]) {
        NSLog(@"nodeContent: %@",nodeContent);   // it becomes null
        finaldata = nodeContent;
        NSLog(@"finaldata: %@",finaldata);          // it becomes null
        NSLog(@"username.text: %@",username.text);  // it becomes null
        username.text = finaldata; 

    }
    username.text = finaldata;
}

最佳答案

代码::

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {

   NSLog(@"DONE. Received Bytes: %d", [webData length]);
   NSString *theXML = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding];
NSLog(@"%@",theXML);

   theXML = [theXML stringByReplacingOccurrencesOfString:@"&lt;" withString:@"<"];
   theXML = [theXML stringByReplacingOccurrencesOfString:@"&gt;" withString:@">"];
   theXML = [theXML stringByReplacingOccurrencesOfString:@"&amp;" withString:@"&"];

   NSString *str, *result;
   result = [[[NSString alloc] initWithFormat:@""] autorelease];

   NSArray *array=[theXML componentsSeparatedByString:@"<CelsiusToFahrenheitResult>"];
   for(int i=1;i<[array count];i++)
   {
      str=[array objectAtIndex:i];

      NSRange ranfrom=[str rangeOfString:@"</CelsiusToFahrenheitResult>"];
      result =[str substringToIndex:ranfrom.location];
   }

   NSLog(@"\n -> %@", result);

   t2.text = result; // Your Second textfield

   [connection release];
}

它肯定会起作用。 谢谢。

关于iphone 网络服务应用程序，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14269564/