Parsing Local XML File Works, Downloaded XML File Doesn't - iphone

Question

I have this problem when I fetch an XML file from the internet and then parse it, where I get this error:
Error while parsing the document: Error Domain=SMXMLDocumentErrorDomain Code=1 "Malformed XML document. Error at line 1:1." UserInfo=0x886e880 {LineNumber=1, ColumnNumber=1, NSLocalizedDescription=Malformed XML document. Error at line 1:1., NSUnderlyingError=0x886e7c0 "The operation couldn’t be completed. (NSXMLParserErrorDomain error 5.)"}
Here is an extract from the code (I believe I am only showing the most relevant code, if you need more, please ask.)
// Create a URL Request and set the URL
NSURL *url = [NSURL URLWithString:#"http://***.xml"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
// Display the network activity indicator
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
// Perform the request on a new thread so we don't block the UI
dispatch_queue_t downloadQueue = dispatch_queue_create("Download queue", NULL);
dispatch_async(downloadQueue, ^{
NSError* err = nil;
NSHTTPURLResponse* rsp = nil;
// Perform the request synchronously on this thread
NSData *rspData = [NSURLConnection sendSynchronousRequest:request returningResponse:&rsp error:&err];
// Once a response is received, handle it on the main thread in case we do any UI updates
dispatch_async(dispatch_get_main_queue(), ^{
// Hide the network activity indicator
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
if (rspData == nil || (err != nil && [err code] != noErr)) {
// If there was a no data received, or an error...
NSLog(#"No data received.");
} else {
// Cache the file in the cache directory
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString* path = [[paths objectAtIndex:0] stringByAppendingPathComponent:#"init.xml"];
//NSLog(#"%#",path);
[[NSFileManager defaultManager] removeItemAtPath:path error:nil];
[data writeToFile:path atomically:YES];
//NSString *sampleXML = [[NSBundle mainBundle] pathForResource:#"sample" ofType:#"xml"];
NSData *data = [NSData dataWithContentsOfFile:path];
// create a new SMXMLDocument with the contents of sample.xml
NSError *error;
SMXMLDocument *document = [SMXMLDocument documentWithData:data error:&error];
// check for errors
if (error) {
NSLog(#"Error while parsing the document: %#", error);
// return;
}
Firstly, I have connected the iPhone to an XML feed which it has fetched and written to the path of the variable path. Then I check for errors in the XML document and I get that error every time.
However, if I use a local XML file which I have placed in the main folder of my application there is no problem fetching all the data.
Using the code:
NSString *sampleXML = [[NSBundle mainBundle] pathForResource:#"sample" ofType:#"xml"];
So does anyone have an idea as to what I can have done wrong? It seems as if it doesn't download and store the XML file to the iPhone's cache, however NSLog(); seems to show it differently. Obviously the local file is the same as the file on the internet.
Furthermore, I already tried to save the file to the path without any results, though.

Answer 1

A couple of observations:
The key issue would appear to be that you retrieved the data in rspData, but when you write it to your temporary file, you're writing data, not rspData. So change the line that says:
[data writeToFile:path atomically:YES];
to
[rspData writeToFile:path atomically:YES];
Frankly, I don't even see the data variable defined at that point (do you have some ivar lingering about?). I'd be ruthless about getting rid of any ivars or other variables that you don't need, so that you don't accidentally refer to some unused variable. Anyway, just use the rspData that you retrieved rather than some other variable.
Why are you even writing that to a file, only to then read the file into another NSData that you pass to your XML parser? That seems entirely unnecessary. Just go ahead and use the rspData you initially retrieved. If you want to save the NSData to a file so you can examine it later for debugging purposes, that's fine. But there's no point in re-retrieving the NSData from the file, as you already have it in a rspData already.
If you encounter these errors in the future, feel free to examine the contents of the NSData variable with a debugging line of code, something like:
NSLog(#"rspData = %#", [[NSString alloc] initWithData:rspData encoding:NSUTF8StringEncoding]);
When you do that, you can look at the string rendition of the NSData, and usually the problem will become self evident.
As a complete aside, in your debugging error handler, you have a line that says:
NSLog(#"No data received.");
I might suggest you always include any errors that might be provided, e.g.:
NSLog(#"No data received: error = %#", err);
iOS provides useful error messages, so you should avail yourself of those.