Getting data from server in objective c class - objective-c

Question

Im trying to make a class where when I create an instance of that class and pass a username and password to the class it sends it to the server and gives whether its a valid password or whether theres an error. When I try to access the response variable from the instance I get null. I suspect that the methods begin called -(void)connectionDidFinishLoading:(NSURLConnection *)connection is happening before the variable is being accessed. Is there a better way to access the variable or call the method so it happens before the variable is accessed
Login View Controller.h
#interface LoginViewController : UIViewController
-(IBAction)Login:(id)sender;
#property (nonatomic, retain) IBOutlet UITextField *username;
#property (nonatomic, retain) IBOutlet UITextField *password;
#end
Login View Controller.m
#import "LoginViewController.h"
#import "Users.h"
#interface LoginViewController ()
#end
#implementation LoginViewController
#synthesize username, password;
/*
-(IBAction)Login:(id)sender{
Users *user = [[Users alloc] init];
[user Login:username.text :password.text];
if ([user.serverResponse isEqual: #"Status:Created"]) {
[self performSegueWithIdentifier:#"home" sender:nil];
}
else{
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:#""
message:#"Username or Password is incorrect"
delegate:self
cancelButtonTitle:#"Cancel"
otherButtonTitles:#"OK", nil];
[alert show];
}
NSLog(#"%#",user.serverResponse);
}
#end
Users Class.h
#import <Foundation/Foundation.h>
#interface Users : NSObject
- (void)Login:(NSString*)username :(NSString*)password;
- (void)Signup:(NSString*)username :(NSString*)password :(NSString*)password_confirmation :(NSString*)email;
#property (nonatomic, retain) NSMutableData *response;
#property (nonatomic, retain) NSString *serverResponse;
#end
Users Class.m
#import "Users.h"
#define loginURL #"linktoserver"
#define signupURL #"linktoserver"
#implementation Users
#synthesize response, serverResponse;
- (void)Login:(NSString*)username :(NSString*)password{
NSMutableData *data = [[NSMutableData alloc] init];
self.response = data;
NSURL *url = [NSURL URLWithString:loginURL];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[url standardizedURL]];
// Http Method
[request setHTTPMethod:#"POST"];
// Intializes Post Data
NSString *postData = [NSString stringWithFormat:#"username=%#&password=%#", username, password];
NSString *postLength = [NSString stringWithFormat:#"%lu", (unsigned long)[postData length]];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:[postData dataUsingEncoding:NSUTF8StringEncoding]];
// Intializes Connection Request
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection start];
}
#pragma Connection
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data
{
[response appendData:data];
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
serverResponse = [[NSString alloc] initWithData:response
encoding:NSUTF8StringEncoding];
}

Answer 1

Use NSURLSession instead of NSURLConnection with delegates (to simplify the process):
[[[NSURLSession sharedSession] dataTaskWithRequest:request
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
if (!error && data){ // here you can check also response.statusCode if needed
NSString *serverResponse = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
dispatch_async(dispatch_get_main_queue(), ^{
completion(serverResponse);
});
}else {
dispatch_async(dispatch_get_main_queue(), ^{
completion(nil);
//show some alert about no connection etc
});
}
}] resume];
add completion to your method
- (void) login:(NSString*)username
password:(NSString*)password
completion:(void (^)(NSSring *response))completion
and then compare response in the completion in the loginViewController
[user login:#"aaa" password:#"bbb" completion:^(NSString *response) {
if ([response isEqualToString:#"ccc"]){
// success!
}else{
// alert
}
};