how I can Modify this code - objective-c

Question

I'm using this function to send a request to a server and receive JSON response in an NSDictionary.
- (void)performRequest:(NSString *)aRequest
{
NSString *string=[NSString stringWithFormat:#"%#%#",baseURL,aRequest];
NSURL *url = [NSURL URLWithString: string];
NSLog(#"string%#",string);
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError)
{
if (data.length > 0 && connectionError == nil)
{
NSDictionary * greeting = [NSJSONSerialization JSONObjectWithData:data
options:0
error:NULL];
NSLog(#"%#",greeting2);
}
}];
}
What I want is to modify it so that it remains a function sending service URL and a separate one where the JSON response comes at a NSDictionary so you can reuse them in other classes.

Answer 1

I used the networking introduced by iOS 7: NSURLSession. This is the networking code I use in a project. But I would suggest you to use AFNetworking instead. That will save you more time on it. It depends on what you want in your application.
+ (void)requestOperationWithMethod:(NSString *)method
withUrl:(NSString *)url
header:(NSDictionary *)header
params:(NSDictionary *)params
completion:(FHCompletionResultBlock)completion {
FHNetworking *network = [FHNetworking shareNetworking];
NSData *bodyData;
NSError *jsonError = nil;
NSData *data = [NSJSONSerialization dataWithJSONObject:params options:kNilOptions error:&jsonError];
if (!jsonError) {
bodyData = data;
}
// prepare http request header and body data fields
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
for (NSString *key in header.allKeys) {
[request setValue:header[key] forHTTPHeaderField:key];
}
[request setHTTPMethod:method];
[request setHTTPBody:bodyData];
[request setTimeoutInterval:30.0f];
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
[[network.session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error){
NSError *jsonError = nil;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&jsonError];
if (jsonError)
completion(nil, jsonError);
else {
NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
if (httpResponse.statusCode >= 400) {
if (json[#"code"] && json[#"error"]) {
NSError *error = [NSError errorWithDomain:#"Error" code:[json[#"code"] integerValue] userInfo:#{NSLocalizedDescriptionKey: NSLocalizedString(json[#"error"], nil)}];
completion(nil, error);
}
else {
NSError *error = [NSError errorWithDomain:#"Error" code:-1 userInfo:#{NSLocalizedDescriptionKey: NSLocalizedString(#"Unknown error", nil)}];
completion(nil, error);
}
}
else {
completion(json, nil);
}
}
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
}] resume];
}

Answer 2

You can change your method to take a completionHandler parameter, itself:
- (void)performRequest:(NSString *)aRequest completionHandler:(void(^)(NSDictionary *responseObject, NSError *error))completionHandler
{
NSString *string=[NSString stringWithFormat:#"%#%#",baseURL,aRequest];
NSURL *url = [NSURL URLWithString: string];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError) {
if (data.length > 0 && connectionError == nil) {
NSError *parseError;
NSDictionary *responseObject = [NSJSONSerialization JSONObjectWithData:data
options:0
error:&parseError];
completionHandler(responseObject, parseError);
} else {
completionHandler(nil, error);
}
}];
}
Now you can call it and supply whatever you want in the completion handler:
[self performRequest:requestString completionHandler:^(NSDictionary *responseObject, NSError *error) {
if (responseObject) {
// everything is good; use your NSDictionary here
} else {
// handle error here
}
}];