AFNetworking authentication with web service - iphone

Question

Having an issue which is more of a design consideration than that of code.
My iOS app interfaces with a json web service. I am using AFNetworking and my issue is basically I need the init function (which authenticates the AFHTTPClient and retrieves a token) to complete entirely before I make any additional requests (that require said token).
From the code below, I would be interested in hearing design approaches to achieving this, I would prefer to keep all requests async an alternative solution would be to make the request in initWithHost:port:user:pass synchronous (not using AFNetworking) which I am aware is bad practice and want to avoid.
DCWebServiceManager.h
#import <Foundation/Foundation.h>
#import "AFHTTPClient.h"
#interface DCWebServiceManager : NSObject
{
NSString *hostServer;
NSString *hostPort;
NSString *hostUser;
NSString *hostPass;
NSString *hostToken;
AFHTTPClient *httpClient;
}
// Designated Initialiser
- (id)initWithHost:(NSString *)host port:(NSString *)port user:(NSString *)user pass:(NSString *)pass;
// Instance Methods
- (void)getFileList;
#end
DCWebServiceManager.m
#import "DCWebServiceManager.h"
#import "AFHTTPClient.h"
#import "AFHTTPRequestOperation.h"
#import "AFJSONRequestOperation.h"
#implementation DCWebServiceManager
- (id)initWithHost:(NSString *)host port:(NSString *)port user:(NSString *)user pass:(NSString *)pass
{
self = [super init];
if (self)
{
hostServer = host;
hostPort = port;
hostUser = user;
hostPass = pass;
NSString *apiPath = [NSString stringWithFormat:#"http://%#:%#/", hostServer, hostPort];
httpClient = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:apiPath]];
[httpClient setAuthorizationHeaderWithUsername:hostUser password:hostPass];
NSMutableURLRequest *request = [httpClient requestWithMethod:#"GET" path:#"authenticate.php" parameters:nil];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject){
// Do operations to parse request token to be used in
// all requests going forward...
// ...
// ...
// Results in setting: hostToken = '<PARSED_TOKEN>'
NSLog(#"HostToken: >>%#<<", hostToken);
} failure:^(AFHTTPRequestOperation *operation, NSError *error){
NSLog(#"ERROR: %#", operation.responseString);
}];
[operation start];
}
return self;
}
- (void)getFileList
{
// *************************
// The issue is here, getFileList gets called before the hostToken is retrieved..
// Make the authenticate request in initWithHost:port:user:pass a synchronous request perhaps??
// *************************
NSLog(#"IN GETFILELIST: %#", hostToken); // Results in host token being nil!!!
NSString *queryString = [NSString stringWithFormat:#"?list&token=%s", hostToken];
NSMutableURLRequest *listRequest = [httpClient requestWithMethod:#"GET" path:queryString parameters:nil];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:listRequest success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON){
NSLog(#"SUCCESS!");
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON){
NSLog(#"ERROR!: %#", error);
}];
[operation start];
}
#end
ViewController.m
....
DCWebServiceManager *manager = [[DCWebServiceManager alloc] initWithHost:#"localhost" port:#"23312" user:#"FOO" pass:#"BAR"];
[manager getFileList];
// OUTPUTS
IN GETFILELIST: (nil)
HostToken: >>sdf5fdsfs46a6cawca6<<
....
...

Answer 1

I'd suggest subclassing AFHTTPClient and adding a +sharedInstance and property for the token.
+ (MyGClient *)sharedInstanceWithHost:(NSString *)host port:(NSString *)port user:(NSString *)user pass:(NSString *)pass {
static MyClient *sharedInstance;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
[... your code from the init ...]
});
return sharedInstance;
}
You can then override enqueueHTTPRequestOperationWithRequest:success:failure to check for the token before enqueueing further operations.
Additionally, you can collect the operations and enqueue them as soon as the token is set by overriding the setter for the property.

Answer 2

Like #patric.schenke said, you can subclass AFHTTPClient if you want to clean up some of your code, but the real issue is that you need to make another request to authenticate (if your token is nil) before making the request to getFileList.
I would recommend using blocks in the same way that AFNetworking is using blocks to remain asynchronous. Move your HTTP call into its own method and call it only when your hostToken is nil:
- (void)getFileList
{
if (self.token == nil) {
[self updateTokenThenWhenComplete:^(void){
// make HTTP call to get file list
}];
} else {
// make HTTP call to get file list
}
}
- (void)updateTokenThenWhenComplete:(void (^))callback
{
//... make HTTP request
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject){
self.token = responseObject.token;
callback();
} failure:^(AFHTTPRequestOperation *operation, NSError *error){
//...
}];
}