'NSString'没有可见的@interface声明select器'appendData'

我正在尝试asynchronous调用服务器（ARC -on）：

NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:request delegate:self]; if (theConnection) { content = [NSMutableData data]; NSLog(@"responseData from setup.php: %@", content); } else { // Inform the user that the connection failed. NSLog(@"error from server response in set up"); } - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { NSLog(@"connection did receive response"); } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [content appendData:data]; NSLog(@"connection did receive data"); } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"connection did finish load"); NSLog(@"Succeeded! Received %@ bytes of data",receivedData); } 

但我有问题从服务器获取内容： – 在didReceiveData函数，下面的错误即将到来： – 'NSString'没有可见的@interface声明select器'appendData'

有人可以build议我哪里可能是错的？

Answer 1

在界面部分的.h文件中，请声明以下内容

 NSMutableData *content;