how to wait the response from a http request in ios - ios

Question

Anybody knows how to wait the response of a http request? In my code, I am doing a http request to an url and then what i need to do, it is to check the http response in order to decide different treatment. I have something like this:
-(void)check{
[self fetchURL:#"http://something"];
if(response != nil || [response length] != 0){
do something....
}
else{
do something else....
}
}
-(void)fetchURL:(NSString *)urlWeb{
NSURL *url = [NSURL URLWithString:urlWeb];
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
[connection start];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
NSLog(#"INSIDE OF didReceiveResponse");
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
NSLog(#"INSIDE OF didFailWithError");
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
NSLog(#"INSIDE OF connectionDidFinishLoading");
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
NSLog(#"inside of didReceiveData");
response = [NSString stringWithUTF8String:[data bytes]];
NSLog(#"response: %#", response);
}
I have been trying different options that I have seen around here, but i cant stop the execution of my code and wait for that answer...that means when I check the response of my http request, it always appears empty or with a nil reference...
any help how to figure out??
thanks

Answer 1

You can't evaluate the response value right after your 'fetchUrl' call, because your request is asynchronous, and your code goes on with the execution without waiting for the answer. You will receive the response value only in one of the delegate method, so there's the place where you should check the result.
If you really want to make a synchronous request you can use sendSynchronousRequest:returningResponse:error: like this
NSError *error;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
if(data){
//use data
}
else{
//check error domain and code
}
(See the Apple NSURLConnection Reference)
But keep in mind that your program will be stuck on this call till it receives a response or goes timeout.

Answer 2

Why don't you write this code:
if(response != nil || [response length] != 0){
do something....
}
else{
do something else....
}
In - (void)connectionDidFinishLoading:(NSURLConnection *)connection; method it wouldn't execute unless you have your complete proper response.
And Just for ado: Right to way to get data properly should be:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[_responseData appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
NSString *string = [[NSString alloc] initWithData:_responseData encoding:NSUTF8StringEncoding];
if (string)
NSLog(#"string = %#", string);
}

Answer 3

Did you try checking the respons witin connectionDidFinishLoading: ?
That is the very delegate method which is called when the data was transferred successfully. Before that point in time, you should not expect any meaningful data.
Besides - didReceiveData should provide you with portions of data received in the meantime. Apparently you do not seem to process it nor just to store it for later evaluation (witin connectionDidFinishLoading)