爲「NSString的」不可見@interface聲明選擇「appendData」

Question

我想異步調用服務器（ARC酮） - ：

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); 
} 

，但我有從服務器獲取內容的問題： - 在didReceiveData功能，下面的錯誤來了： - 爲「NSString的」不可見@interface聲明選擇「appendData」

可有人建議我在哪裏，我可能是錯的？

Answer 1

在接口部分的.h文件中，請聲明如下

NSMutableData *content;