Using sendAsynchronousRequest:queue:completionHandler: for URL request - ios

Question

I'm working on an update of an iOS app that another developer created. He was using ASIHTTPRequest to handle http requests. However, the version of the app I have to work with crashes. Since ASIHTTPRequest is not being updated anymore, I thought then that I should switch to using AFNetworking, but it's far too complicated for me to figure out.
So finally I thought I could just use NSURLConnection on its own.
Here is the original code that I'm trying to replace:
-(NSArray*)readUTF16LEFeed:(NSURL*) urlToRead{
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:urlToRead];
[request startSynchronous];
NSError *error = [request error];
if (!error) {
lastModified = [NSDate date];
NSData *response = [request responseData];//UTF-16LE
NSString* responseString = [[NSString alloc] initWithData:response encoding:NSUTF16LittleEndianStringEncoding];
DLog(#"string is: %#",responseString);
responseString = [responseString stringByReplacingOccurrencesOfString:#"ISO-8859-1" withString:#"UTF16-LE"];
NSData* data = [responseString dataUsingEncoding:NSUTF16LittleEndianStringEncoding];
return [self parseNamesFromXML:data];
}
return nil;
}
And here is what I'm trying to use instead:
-(NSArray*)readUTF16LEFeed:(NSURL*) urlToRead{
NSURLRequest *request = [NSURLRequest requestWithURL:urlToRead];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error ) {
if ([data length] >0 && error == nil)
{
// DO YOUR WORK HERE
lastModified = [NSDate date];
// NSData *response = [request responseData];//UTF-16LE
NSString* responseString = [[NSString alloc] initWithData:data encoding: NSUTF16LittleEndianStringEncoding];
DLog(#"string is: %#",responseString);
responseString = [responseString stringByReplacingOccurrencesOfString:#"ISO-8859-1" withString:#"UTF16-LE"];
NSData* data = [responseString dataUsingEncoding:NSUTF16LittleEndianStringEncoding];
return [self parseNamesFromXML:data];
}
else if ([data length] == 0 && error == nil)
{
NSLog(#"Nothing was downloaded.");
}
else if (error != nil){
NSLog(#"Error = %#", error);
}
}];
return nil;
}
However, I'm getting the error "Incompatible block pointer types sending NSArray to parameter of type void. And also "Control may reach end of non-void block."
How can I get this to work?

Answer 1

Make return type of your method as void. Dont return anything. Just call [self parseNamesFromXML:data]; method.
-(void)readUTF16LEFeed:(NSURL*) urlToRead{
NSURLRequest *request = [NSURLRequest requestWithURL:urlToRead];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error ) {
if ([data length] >0 && error == nil)
{
// DO YOUR WORK HERE
lastModified = [NSDate date];
// NSData *response = [request responseData];//UTF-16LE
NSString* responseString = [[NSString alloc] initWithData:data encoding: NSUTF16LittleEndianStringEncoding];
DLog(#"string is: %#",responseString);
responseString = [responseString stringByReplacingOccurrencesOfString:#"ISO-8859-1" withString:#"UTF16-LE"];
NSData* data = [responseString dataUsingEncoding:NSUTF16LittleEndianStringEncoding];
[self parseNamesFromXML:data];
}
else if ([data length] == 0 && error == nil)
{
NSLog(#"Nothing was downloaded.");
}
else if (error != nil){
NSLog(#"Error = %#", error);
}
}];
}
In parseNamesFromXML method, process your results and assign results array to a property. You can access it where ever you want.
-(void) parseNamesFromXML:(NSData *)xmlData
{
NSError *error;
//DLog(#"data is %#", [[NSString alloc] initWithData:xmlData encoding:NSUTF8StringEncoding ]);
GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:xmlData options:0 error:&error];
if (doc)
{
self.dataArray = [self parseXmlDoc:doc];
}
}

Answer 2

The completion block is called asynchronously, so by the time your code reaches return [self parseNamesFromXML:data]; the methods scope is already done (meaning the method returned nil.
Try using [NSURLConnection sendSynchronousRequest:returningResponse:error:] instead, since the original code is also synchronous.
Edit:
As Julian Król suggested, if you return something within a block, it will be counted as the return value of this block, not of the original method. But since the block does not have a return value, you'll get the compiler error.