IMPORTANT: If you are uploading to a site that requires authentication, the upload progress will be reset to its previous value every time it fails to supply valid authentication. For this reason, it is recommended that you only ever use an upload progress delegate when useSessionPersistence is YES (see below) when communicating with authenticating web servers, and ensure that you authenticate in another request before attempting to track the upload of a large amount of data.

Tracking progress for uploads where the request body is less than 128KB is currently not possible. For requests larger than 128KB, progress delegates will not receive information on the progress of the first 128KB of post data. This is because of limitations in the CFNetwork API. I have filed a feature enhancement with Apple (bug id 6596016), hopefully they will modify CFNetwork in future to make this possible.

Update 21st June 2009: The wonderful folks at Apple were kind enough to address my bug report! In the iPhone 3.0 SDK, it looks like the buffer size has been reduced to 32KB, which makes accurate upload progress tracking a lot more reliable.

Tracking download progress for a single request

In this example, myProgressIndicator is an NSProgressIndicator.

ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

[request setDownloadProgressDelegate:myProgressIndicator];

[request startSynchronous];

NSLog(@"Max: %f, Value: %f", [myProgressIndicator maxValue],[myProgressIndicator doubleValue]);

Tracking download progress for a set of requests

In this example, myProgressIndicator is an UIProgressView, myQueue is an ASINetworkQueue.

- (void)fetchThisURLFiveTimes:(NSURL *)url

{

   [myQueue cancelAllOperations];

   [myQueue setDownloadProgressDelegate:myProgressIndicator];

   [myQueue setDelegate:self];

   [myQueue setRequestDidFinishSelector:@selector(queueComplete:)];

   int i;

   for (i=0; i<; i++) {
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

      [myQueue addOperation:request];

   }

   [myQueue go];

}

 

- (void)queueComplete:(ASINetworkQueue *)queue

{

   NSLog(@"Value: %f", [myProgressIndicator progress]);

}

Tracking upload progress for a single request

In this example, myProgressIndicator is an UIProgressView.

ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];

[request setPostValue:@"Ben" forKey:@"first_name"];

[request setPostValue:@"Copsey" forKey:@"last_name"];

[request setUploadProgressDelegate:myProgressIndicator];

[request startSynchronous];

NSLog(@"Value: %f",[myProgressIndicator progress]);

Tracking upload progress for a set of requests

In this example, myProgressIndicator is an NSProgressIndicator, myQueue is an ASINetworkQueue.

- (void)uploadSomethingFiveTimes:(NSURL *)url

{

   [myQueue cancelAllOperations];

   [myQueue setUploadProgressDelegate:myProgressIndicator];

   [myQueue setDelegate:self];

   [myQueue setRequestDidFinishSelector:@selector(queueComplete:)];

   int i;

   for (i=0; i<; i++) {
ASIHTTPRequest *request = [ASIFormDataRequest requestWithURL:url];

      [request setPostBody:[@"Some data" dataUsingEncoding:NSUTF8StringEncoding]];

      [myQueue addOperation:request];

   }

   [myQueue go];

}

 

- (void)queueComplete:(ASINetworkQueue *)queue

{

   NSLog(@"Max: %f, Value: %f", [myProgressIndicator maxValue],[myProgressIndicator doubleValue]);

}

Accurate progress vs simple progress

ASIHTTPRequest provides two approaches for displaying progress, simple progress, and accurate progress. They are controlled using the showAccurateProgress of ASIHTTPRequests and ASINetworkQueues. When you set showAccurateProgress on a request, it affects only that request. When you set it on a queue, it affects all requests in the queue.

Simple progress

When using simple progress, progress will update only when a request completes. For a single request, this means you get two progress updates - 0% complete, and 100% complete. For a queue with four requests, you would get five progress updates, 0%, 25%, 50%, 75% and 100%, with each increment representing a request that has completed.

Simple progress (showAccurateProgress = NO) is the default for ASINetworkQueues, and is well suited to queues with a large number of small uploads / downloads.

Accurate progress

When using accurate progress, progress will be updated as bytes are sent or received. It is best for requests that send or receive a large amount of data, and will give a much better indication of how much data has been sent or received for requests that take some time.

Using accurate progress will slightly degrade the performance of uploads, since progress delegates (which are likely to be UIProgressViews or NSProgressIndicators) will be redrawn much more frequently.

Using accurate progress has a much greater effect on performance for downloads when using a queue, since the queue will first perform a HEAD request for each GET request it contains so it can determine the overall size of the data to be downloaded before downloading commences. Using accurate progress is highly recommended if you are downloading large files from a queue, but you should avoid it for queues that contain a large number of small downloads.

Accurate progress (showAccurateProgress == YES) is the default for ASIHTTPRequests that run synchronously.

Custom progress tracking

大多数情况下，设置uploadProgressDelegate and/or downloadProgressDelegate to an NSProgressIndicator or UIProgressView。如果想执行更为复杂的进度跟踪的话，delegates应该实现方法setProgress: (iOS) or setDoubleValue: / setMaxValue: (Mac).这些方法使你得到发送或接收时确切的字节数。

Methods for downloadProgressDelegates

• request:didReceiveBytes: will be called on your downloadProgressDelegate each time the request downloads a bit more data. (Note that this is distinct from the request:didReceiveData: method that you regular delegate may implement). 当有数据下载接收时就会调用到。
• request:incrementDownloadSizeBy: will be called when the size of the download changes, with the passed parameter being the amount you should increase the size of the download by. This usually happens when the request receives response headers and finds out the size of the download. 当下载数据大小发生变化时调用此方法。参数就是需要增加的大小。

Methods for uploadProgressDelegates

• request:didSendBytes: will be called on your uploadProgressDelegate each time the request has been able to send a bit more data. Important: This method will be called with a number less than zero when a request needs to remove upload progress (usually when it has uploaded the data, but failed authentication or needs to run again for some other reason). 因为括号中的这些情况所以上传的大小可能是负数
• request:incrementUploadSizeBy: will be called when the size of the upload changes. The passed size will frequently be below zero, as the request adjusts the upload size to take account of the size of the internal buffer used by the OS.

• Handling HTTP authentication

If you’re connecting to a server that requires authentication, you might want to take a look at this flowchart that shows how ASIHTTPRequest finds and applies credentials to requests.

Specifying a username and password to use in the URL

NSURL *url = [NSURL URLWithString:@"http://username:password@allseeing-i.com/top_secret/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

Setting a username and password to use on the request

NSURL *url = [NSURL URLWithString:@"http://allseeing-i.com/top_secret/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

[request setUsername:@"username"];

[request setPassword:@"password"];

Storing credentials in the keychain

If you turn on keychainPersistence, any valid username and password supplied will be stored in the keychain. Subsequent requests will reuse the username and password from the keychain, even if you quit and relaunch the application.

NSURL *url = [NSURL URLWithString:@"http://allseeing-i.com/top_secret/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

[request setUseKeychainPersistence:YES];

[request setUsername:@"username"];

[request setPassword:@"password"];

If you want to use the keychain but would rather manage it yourself, you might find the class methods relating to the keychain in ASIHTTPRequest.h helpful.

Storing credentials in the session

If useSessionPersistence is turned on (it is by default), ASIHTTPRequest stores credentials in memory and can re-use them for subsequent requests.

NSURL *url = [NSURL URLWithString:@"http://allseeing-i.com/top_secret/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

[request setUsername:@"username"];

[request setPassword:@"password"];

[request setUseSessionPersistence:YES]; //Shouldn't be needed as this is the default

 

//Should reuse our username and password

request = [ASIHTTPRequest requestWithURL:url];

NTLM authentication

To authenticate with a Windows server that uses the NTLM scheme, you also need to specify the domain you are authenticating against.

NSURL *url = [NSURL URLWithString:@"http://my.windows.server/top_secret/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

[request setUsername:@"username"];

[request setPassword:@"password"];

[request setDomain:@"my-domain"];

Using delegation to provide credentials

Rather than specifying authentication credentials in advance, you might prefer to let each request ask its delegate for credentials if it can’t find them in the session authentication cache or keychain. This might be helpful if you want to connect to a server where you aren’t sure in advance what kind of authentication (if any) will be required.

Make sure your delegate implements authenticationNeededForRequest:, and ASIHTTPRequest will pause a request while it waits for the delegate to let it know what credentials to use. When you have the credentials you need, simply set them on the request, and call [request retryUsingSuppliedCredentials];. If you want to cancel, you must call [request cancelAuthentication]. This will cancel the request.

As of v1.0.8, request delegates will only receive one authenticationNeededForRequest: or proxyAuthenticationNeededForRequest: at once. Other requests requiring authentication will pause while the delegate handles the first request. If credentials are provided, any other requests currently in progress will attempt to reuse them, assuming they are valid for the url. If the delegate cancels authentication, and the queue’s shouldCancelAllRequestsOnFailure is YES, all the other requests will cancel without attempting to ask for credentials.

Using the built-in authentication dialog (currently iOS only)

New in v1.0.8 is the ASIAuthenticationDialog class. This is primarily used for working with authenticating proxies (see below), but it can be used to ask the user for credentials for authenticating webservers.

For the best user experience, most apps that connect to a single service should implement authenticationNeededForRequest: in their request delegates, or avoid the use of delegation-style authentication altogether. However, there may be some occasions when the use of ASIHTTPRequest’s standard authentication dialog for regular authentication may be advantageous:

• You don’t want to create your own login form
• You may need to fetch data from an external source, and aren’t certain if it will require authentication or not

For these cases, set shouldPresentAuthenticationDialog to true on your requests, and, if your delegate does not implement authenticationNeededForRequest:, users will see the dialog.

Only one dialog can appear at once, and other requests requiring authentication will pause while the dialog is visible. If credentials are provided, any other requests currently in progress will attempt to reuse them, assuming they are valid for the url. If the delegate cancels authentication, and the queue’s shouldCancelAllRequestsOnFailure is YES (as per the default), all the other requests will cancel without attempting to ask for credentials.

The authentication dialog will not appear for synchronous requests.

The dialog is partly modelled on the authentication dialog that Safari uses on the iPhone, and includes:

• A message to indicate these credentials are for a webserver (as opposed to a proxy)
• The hostname or IP of the server you are connecting to
• The authentication realm (if one was supplied)
• Fields to enter a username and password
• When connecting to a server that uses the NTLM scheme, the dialog also includes a field for the domain
• A note about whether the credentials are sent in plain text or not (ie: They are sent in plain text only when using Basic authentication without SSL)

If you want to change the look and feel, subclass ASIHTTPRequest, and override showAuthenticationDialog to show your custom dialog or ASIAuthenticationDialog subclass.

Presenting credentials before the server asks for them

ASIHTTPRequest can present credentials to the server (if it has credentials to use) when it first makes a request, rather than waiting for the server to ask for credentials. This can result in better performance for applications using authentication, since it avoids an extra request.

To trigger this behaviour for requests using Basic authentication, you should manually set the request’s authenticationScheme to use Basic:

[request setAuthenticationScheme:(NSString *)kCFHTTPAuthenticationSchemeBasic];

For other authentication schemes, credentials can be presented before the server asks for them, but only after another request has successfully authenticated with the server.

You may wish to disable this feature if:

• Your application may use multiple sets of credentials to talk to the same server at once
• Security is paramount for your application. Using this feature is inherently less secure, since credentials are sent before you have a chance to validate that you are connecting to the server you thought you were connecting to.

To disable this feature, use this code:

[request setShouldPresentCredentialsBeforeChallenge:NO];

Cookies

Persistent cookies

ASIHTTPRequest allows you to use the global store shared by all Mac OS X applications that use the CFNetwork or NSURLRequest APIs. If useCookiePersistence is on (it is by default), cookies will be stored in the shared NSHTTPCookieStorage container, and reused on other requests automatically. It’s worth noting that ASIHTTPRequest might present cookies created in other applications if they are valid for a particular request.

You can clear all cookies created during a session like so:

[ASIHTTPRequest setSessionCookies:nil];

In this case, ‘session cookies’ refers to ALL cookies created during a session, rather cookies with no expiry date (often referred to as session cookies) that are removed when the application quits.

Alternatively, the convenience class method clearSession will clear all cookies created during the session, along with any cached authentication data.

Handling cookies yourself

If you prefer, you can turn off useCookiePersistence, and manage the set of cookies for a particular request manually:

//Create a cookie
NSDictionary *properties = [[[NSMutableDictionary alloc] init] autorelease];

[properties setValue:[@"Test Value" encodedCookieValue] forKey:NSHTTPCookieValue];

[properties setValue:@"ASIHTTPRequestTestCookie" forKey:NSHTTPCookieName];

[properties setValue:@".allseeing-i.com" forKey:NSHTTPCookieDomain];

[properties setValue:[NSDate dateWithTimeIntervalSinceNow:*] forKey:NSHTTPCookieExpires];

[properties setValue:@"/asi-http-request/tests" forKey:NSHTTPCookiePath];
NSHTTPCookie *cookie = [[[NSHTTPCookie alloc] initWithProperties:properties] autorelease];

 

//This url will return the value of the 'ASIHTTPRequestTestCookie' cookie

url = [NSURL URLWithString:@"http://allseeing-i.com/ASIHTTPRequest/tests/read_cookie"];

request = [ASIHTTPRequest requestWithURL:url];

[request setUseCookiePersistence:NO];

[request setRequestCookies:[NSMutableArray arrayWithObject:cookie]];

[request startSynchronous];

 

//Should be: I have 'Test Value' as the value of 'ASIHTTPRequestTestCookie'

NSLog(@"%@",[request responseString]);