AFNetworking and synchronous request to fulfil online registration process - ios

Question

I am using AFNetworking and I've read that synchronous responses are discouraged. yet I need to check whether a user already exist in the online database before the person can go to the next stage of the app. Yes, a typical registration process.
My code as it stands it returns NO because is asynchronous. I need to find a way to check for the success call and return YES or NO depending on this callback.
Could anyone point me in the right direction of how to write an app that waits for the success call so that I know that the user has not been set?
-(BOOL)doesTheUserExistAlreadyOnServer:(NSString *)parsedEmail
{
BOOL *methodResponse = NO;
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:#"http://www.myurl.co.uk/"]];
NSMutableURLRequest *request = [httpClient requestWithMethod:#"POST"
path:#"http://www.myurl.co.uk/igym.php"
parameters:#{#"myvar2":#"piggy"}];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[httpClient registerHTTPOperationClass:[AFHTTPRequestOperation class]];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
// Print the response body in text
// NSLog(#"Response: %#", [[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding]);
if ([[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding] isEqualToString:#"piggy"]) {
__block methodResponse = YES;
NSLog(#"%#",[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding]);
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];
[operation start];
return (BOOL)methodResponse;
}
EDIT:
I solved the problem using the following logic.
The user clicks on the registration button. The main method does all the preliminary non-web checks, then calls the [self doesTheUserExistAlreadyOnServer:_email.text];
that method code is now
-(void)doesTheUserExistAlreadyOnServer:(NSString *)parsedEmail
{
if(![_spinner isAnimating])
{
[_spinner startAnimating];
}
__block RegistrationViewController* me = self;
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:#"http://www.myurl.co.uk/"]];
NSMutableURLRequest *request = [httpClient requestWithMethod:#"POST"
path:#"http://www.myurl.co.uk/igym.php"
parameters:#{#"myvar2":#"piggy"}];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[httpClient registerHTTPOperationClass:[AFHTTPRequestOperation class]];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
// Print the response body in text
if ([[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding] isEqualToString:#"piggy"]) {
NSLog(#"%#",[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding]);
[me registrationPartTwo:YES];
} else
{
[me registrationPartTwo:NO];
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];
[operation start];
}
Then once that block/callback is successful it calls
-(void)registrationPartTwo:(BOOL)doesItExistOnServer
{
[_spinner stopAnimating];
NSString *emailAlreadyInUseMessage = [NSString stringWithFormat:#"This email is already in use"];
if (doesItExistOnServer)
{
self.screenMsg.text = emailAlreadyInUseMessage;
//here more code to send the user the the next step
}
}
basically i solved this using a 2method registration process dependant upon callback, dont know if thats the best or most efficient way. but thats the way i could solve it on my own.

Answer 1

Use a delegate callback to notify when the operation completes. If needed, before starting the operation, put up an UIActivityIndicatorView (the spinner) to prevent the user from interacting with the app.