How to use stringWithContentsOfURL:encoding:error:?

Question

I am trying to use initWithContentsOfURL:encoding:error: like this :

NSURL *url = [[NSURL alloc] initWithString:@"http://my_url.com/my_file.xml"];
NSError *error = nil;
NSString *my_string = [[NSString alloc] initWithContentsOfURL:url
encoding:NSUTF8StringEncoding
error:&error];

I get a empty my_string variable.

I tried the initWithContentsOfURL: method (which is deprecated in iOS 2.0) and I get the content of my page. But I still need to specify a encoding language.

What's wrong ?

Thanks :)

Answer 1

the encoding of your file is probably not UTF8.

If you don't know the encoding of your file, you could try this method:

- (id)initWithContentsOfURL:(NSURL *)url usedEncoding:(NSStringEncoding *)enc error:(NSError **)error

---

you have to pass a pointer to a NSStringEncoding, like you did with error.:

NSURL *url = [[NSURL alloc] initWithString:@"http://my_url.com/my_file.xml"];
NSError *error = nil;
NSStringEncoding encoding;
//NSString *my_string = [[NSString alloc] initWithContentsOfURL:url
//                                                     encoding:NSUTF8StringEncoding
//                                                        error:&error];
NSString *my_string = [[NSString alloc] initWithContentsOfURL:url
                                                 usedEncoding:&encoding 
                                                        error:&error];

after this your encoding is present in the encoding variable. If you are not interested in the used encoding, I guess you could pass NULL as pointer as well.

Answer 2

Why not use a request and connection to get the info back in an NSData object? Something like this:

NSURL *url = [[NSURL alloc] initWithString:@"http://my_url.com/my_file.xml"];

NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:url];
[request setHTTPMethod:@"GET"];

NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];

    [conn start];

if(conn){
    // Data Received
    responseData = [[NSMutableData alloc] init];
}

and then in your connection:didRecieveData delegate method, put something like this

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

[self.responseData appendData:data];
}

and then once the connection is finished loading convert the data to a string:

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
     NSString *string = [[NSString alloc] initWithData:responseData encoding:NSASCIIStringEncoding];
}

Not the most straightforward method, but that should get you your XML string. Also if you need to parse the XML once you get it back, you can directly pass the responseData to an NSXMLParser without any conversion. :)