AFURLConnectionOperation Class Reference
Inherits from | NSOperation |
Conforms to | NSCoding NSCopying NSURLConnectionDataDelegate NSURLConnectionDelegate |
Declared in | AFURLConnectionOperation.h |
Overview
AFURLConnectionOperation
is a subclass of NSOperation
that implements NSURLConnection
delegate methods.
Subclassing Notes
This is the base class of all network request operations. You may wish to create your own subclass in order to implement additional NSURLConnection
delegate methods (see “NSURLConnection
Delegate Methods” below), or to provide additional properties and/or class constructors.
If you are creating a subclass that communicates over the HTTP or HTTPS protocols, you may want to consider subclassing AFHTTPRequestOperation
instead, as it supports specifying acceptable content types or status codes.
NSURLConnection Delegate Methods
AFURLConnectionOperation
implements the following NSURLConnection
delegate methods:
connection:didReceiveResponse:
connection:didReceiveData:
connectionDidFinishLoading:
connection:didFailWithError:
connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:
connection:willCacheResponse:
connection:canAuthenticateAgainstProtectionSpace:
connection:didReceiveAuthenticationChallenge:
If any of these methods are overridden in a subclass, they must call the super
implementation first.
Class Constructors
Class constructors, or methods that return an unowned instance, are the preferred way for subclasses to encapsulate any particular logic for handling the setup or parsing of response data. For instance, AFJSONRequestOperation
provides JSONRequestOperationWithRequest:success:failure:
, which takes block arguments, whose parameter on for a successful request is the JSON object initialized from the response
data
.
Callbacks and Completion Blocks
The built-in completionBlock
provided by NSOperation
allows for custom behavior to be executed after the request finishes. It is a common pattern for class constructors in subclasses to take callback block parameters, and execute them conditionally in the body of its completionBlock
. Make sure to handle cancelled operations appropriately when setting a completionBlock
(i.e. returning early before parsing response data). See the implementation of any of the AFHTTPRequestOperation
subclasses for an example of this.
Subclasses are strongly discouraged from overriding setCompletionBlock:
, as AFURLConnectionOperation
’s implementation includes a workaround to mitigate retain cycles, and what Apple rather ominously refers to as “The Deallocation Problem”.
NSCoding & NSCopying Conformance
AFURLConnectionOperation
conforms to the NSCoding
and NSCopying
protocols, allowing operations to be archived to disk, and copied in memory, respectively. However, because of the intrinsic limitations of capturing the exact state of an operation at a particular moment, there are some important caveats to keep in mind:
NSCoding Caveats
- Encoded operations do not include any block or stream properties. Be sure to set
completionBlock
,outputStream
, and any callback blocks as necessary when using-initWithCoder:
orNSKeyedUnarchiver
. - Operations are paused on
encodeWithCoder:
. If the operation was encoded while paused or still executing, its archived state will returnYES
forisReady
. Otherwise, the state of an operation when encoding will remain unchanged.
NSCopying Caveats
-copy
and-copyWithZone:
return a new operation with theNSURLRequest
of the original. So rather than an exact copy of the operation at that particular instant, the copying mechanism returns a completely new instance, which can be useful for retrying operations.- A copy of an operation will not include the
outputStream
of the original. - Operation copies do not include
completionBlock
.completionBlock
often strongly captures a reference toself
, which would otherwise have the unintuitive side-effect of pointing to the original operation when copied.
Tasks
Accessing Run Loop Modes
-
runLoopModes
The run loop modes in which the operation will run on the network thread. By default, this is a single-member set containing
propertyNSRunLoopCommonModes
.
Getting URL Connection Information
-
request
The request used by the operation’s connection.
property -
response
The last response received by the operation’s connection.
property -
error
The error, if any, that occurred in the lifecycle of the request.
property
Getting Response Data
-
responseData
The data received during the request.
property -
responseString
The string representation of the response data.
property -
responseStringEncoding
The string encoding of the response.
property
Accessing Streams
-
inputStream
The input stream used to read data to be sent during the request.
property -
outputStream
The output stream that is used to write data received until the request is finished.
property
Managing Request Operation Information
-
userInfo
The user info dictionary for the receiver.
property
Initializing an AFURLConnectionOperation Object
-
– initWithRequest:
Initializes and returns a newly allocated operation object with a url connection configured with the specified url request.
Pausing / Resuming Requests
-
– pause
Pauses the execution of the request operation.
-
– isPaused
Whether the request operation is currently paused.
-
– resume
Resumes the execution of the paused request operation.
Configuring Backgrounding Task Behavior
-
– setShouldExecuteAsBackgroundTaskWithExpirationHandler:
Specifies that the operation should continue execution after the app has entered the background, and the expiration handler for that background task.
Setting Progress Callbacks
-
– setUploadProgressBlock:
Sets a callback to be called when an undetermined number of bytes have been uploaded to the server.
-
– setDownloadProgressBlock:
Sets a callback to be called when an undetermined number of bytes have been downloaded from the server.
Setting NSURLConnection Delegate Callbacks
-
– setAuthenticationAgainstProtectionSpaceBlock:
Sets a block to be executed to determine whether the connection should be able to respond to a protection space’s form of authentication, as handled by the
NSURLConnectionDelegate
methodconnection:canAuthenticateAgainstProtectionSpace:
. -
– setAuthenticationChallengeBlock:
Sets a block to be executed when the connection must authenticate a challenge in order to download its request, as handled by the
NSURLConnectionDelegate
methodconnection:didReceiveAuthenticationChallenge:
. -
– setRedirectResponseBlock:
Sets a block to be executed when the server redirects the request from one URL to another URL, or when the request URL changed by the
NSURLProtocol
subclass handling the request in order to standardize its format, as handled by theNSURLConnectionDelegate
methodconnection:willSendRequest:redirectResponse:
. -
– setCacheResponseBlock:
Sets a block to be executed to modify the response a connection will cache, if any, as handled by the
NSURLConnectionDelegate
methodconnection:willCacheResponse:
.
Properties
error
The error, if any, that occurred in the lifecycle of the request.
@property (readonly, nonatomic, strong) NSError *error
Discussion
The error, if any, that occurred in the lifecycle of the request.
Declared In
AFURLConnectionOperation.h
inputStream
The input stream used to read data to be sent during the request.
@property (nonatomic, strong) NSInputStream *inputStream
Discussion
The input stream used to read data to be sent during the request.
@discussion This property acts as a proxy to the HTTPBodyStream
property of request
.
Declared In
AFURLConnectionOperation.h
outputStream
The output stream that is used to write data received until the request is finished.
@property (nonatomic, strong) NSOutputStream *outputStream
Discussion
The output stream that is used to write data received until the request is finished.
@discussion By default, data is accumulated into a buffer that is stored into responseData
upon completion of the request. When outputStream
is set, the data will not be accumulated into an internal buffer, and as a result, the responseData
property of the completed request will be nil
. The output stream will be scheduled in the network thread runloop upon being set.
Declared In
AFURLConnectionOperation.h
request
The request used by the operation’s connection.
@property (readonly, nonatomic, strong) NSURLRequest *request
Discussion
The request used by the operation’s connection.
Declared In
AFURLConnectionOperation.h
response
The last response received by the operation’s connection.
@property (readonly, nonatomic, strong) NSURLResponse *response
Discussion
The last response received by the operation’s connection.
Declared In
AFURLConnectionOperation.h
responseData
The data received during the request.
@property (readonly, nonatomic, strong) NSData *responseData
Discussion
The data received during the request.
Declared In
AFURLConnectionOperation.h
responseString
The string representation of the response data.
@property (readonly, nonatomic, copy) NSString *responseString
Discussion
The string representation of the response data.
Declared In
AFURLConnectionOperation.h
responseStringEncoding
The string encoding of the response.
@property (readonly, nonatomic, assign) NSStringEncoding responseStringEncoding
Discussion
The string encoding of the response.
@discussion If the response does not specify a valid string encoding, responseStringEncoding
will return NSUTF8StringEncoding
.
Declared In
AFURLConnectionOperation.h
runLoopModes
The run loop modes in which the operation will run on the network thread. By default, this is a single-member set containing NSRunLoopCommonModes
.
@property (nonatomic, strong) NSSet *runLoopModes
Discussion
The run loop modes in which the operation will run on the network thread. By default, this is a single-member set containing NSRunLoopCommonModes
.
Declared In
AFURLConnectionOperation.h
Instance Methods
initWithRequest:
Initializes and returns a newly allocated operation object with a url connection configured with the specified url request.
- (id)initWithRequest:(NSURLRequest *)urlRequest
Parameters
- urlRequest
The request object to be used by the operation connection.
@discussion This is the designated initializer.
Discussion
Initializes and returns a newly allocated operation object with a url connection configured with the specified url request.
Declared In
AFURLConnectionOperation.h
isPaused
Whether the request operation is currently paused.
- (BOOL)isPaused
Return Value
YES
if the operation is currently paused, otherwise NO
.
Discussion
Whether the request operation is currently paused.
Declared In
AFURLConnectionOperation.h
pause
Pauses the execution of the request operation.
- (void)pause
Discussion
Pauses the execution of the request operation.
@discussion A paused operation returns NO
for -isReady
, -isExecuting
, and -isFinished
. As such, it will remain in an NSOperationQueue
until it is either cancelled or resumed. Pausing a finished, cancelled, or paused operation has no effect.
Declared In
AFURLConnectionOperation.h
resume
Resumes the execution of the paused request operation.
- (void)resume
Discussion
Resumes the execution of the paused request operation.
@discussion Pause/Resume behavior varies depending on the underlying implementation for the operation class. In its base implementation, resuming a paused requests restarts the original request. However, since HTTP defines a specification for how to request a specific content range, AFHTTPRequestOperation
will resume downloading the request from where it left off, instead of restarting the original request.
Declared In
AFURLConnectionOperation.h
setAuthenticationAgainstProtectionSpaceBlock:
Sets a block to be executed to determine whether the connection should be able to respond to a protection space’s form of authentication, as handled by the NSURLConnectionDelegate
method connection:canAuthenticateAgainstProtectionSpace:
.
- (void)setAuthenticationAgainstProtectionSpaceBlock:(BOOL ( ^ ) ( NSURLConnection *connection , NSURLProtectionSpace *protectionSpace ))block
Parameters
- block
A block object to be executed to determine whether the connection should be able to respond to a protection space’s form of authentication. The block has a
BOOL
return type and takes two arguments: the URL connection object, and the protection space to authenticate against.@discussion If
_AFNETWORKING_ALLOW_INVALID_SSL_CERTIFICATES_
is defined,connection:canAuthenticateAgainstProtectionSpace:
will accept invalid SSL certificates, returningYES
if the protection space authentication method isNSURLAuthenticationMethodServerTrust
.
Discussion
Sets a block to be executed to determine whether the connection should be able to respond to a protection space’s form of authentication, as handled by the NSURLConnectionDelegate
method connection:canAuthenticateAgainstProtectionSpace:
.
Declared In
AFURLConnectionOperation.h
setAuthenticationChallengeBlock:
Sets a block to be executed when the connection must authenticate a challenge in order to download its request, as handled by the NSURLConnectionDelegate
method connection:didReceiveAuthenticationChallenge:
.
- (void)setAuthenticationChallengeBlock:(void ( ^ ) ( NSURLConnection *connection , NSURLAuthenticationChallenge *challenge ))block
Parameters
- block
A block object to be executed when the connection must authenticate a challenge in order to download its request. The block has no return type and takes two arguments: the URL connection object, and the challenge that must be authenticated.
@discussion If
_AFNETWORKING_ALLOW_INVALID_SSL_CERTIFICATES_
is defined,connection:didReceiveAuthenticationChallenge:
will attempt to have the challenge sender use credentials with invalid SSL certificates.
Discussion
Sets a block to be executed when the connection must authenticate a challenge in order to download its request, as handled by the NSURLConnectionDelegate
method connection:didReceiveAuthenticationChallenge:
.
Declared In
AFURLConnectionOperation.h
setCacheResponseBlock:
Sets a block to be executed to modify the response a connection will cache, if any, as handled by the NSURLConnectionDelegate
method connection:willCacheResponse:
.
- (void)setCacheResponseBlock:(NSCachedURLResponse *( ^ ) ( NSURLConnection *connection , NSCachedURLResponse *cachedResponse ))block
Parameters
- block
A block object to be executed to determine what response a connection will cache, if any. The block returns an
NSCachedURLResponse
object, the cached response to store in memory ornil
to prevent the response from being cached, and takes two arguments: the URL connection object, and the cached response provided for the request.
Discussion
Sets a block to be executed to modify the response a connection will cache, if any, as handled by the NSURLConnectionDelegate
method connection:willCacheResponse:
.
Declared In
AFURLConnectionOperation.h
setDownloadProgressBlock:
Sets a callback to be called when an undetermined number of bytes have been downloaded from the server.
- (void)setDownloadProgressBlock:(void ( ^ ) ( NSUInteger bytesRead , long long totalBytesRead , long long totalBytesExpectedToRead ))block
Parameters
- block
A block object to be called when an undetermined number of bytes have been downloaded from the server. This block has no return value and takes three arguments: the number of bytes read since the last time the download progress block was called, the total bytes read, and the total bytes expected to be read during the request, as initially determined by the expected content size of the
NSHTTPURLResponse
object. This block may be called multiple times, and will execute on the main thread.
Discussion
Sets a callback to be called when an undetermined number of bytes have been downloaded from the server.
Declared In
AFURLConnectionOperation.h
setRedirectResponseBlock:
Sets a block to be executed when the server redirects the request from one URL to another URL, or when the request URL changed by the NSURLProtocol
subclass handling the request in order to standardize its format, as handled by the NSURLConnectionDelegate
method connection:willSendRequest:redirectResponse:
.
- (void)setRedirectResponseBlock:(NSURLRequest *( ^ ) ( NSURLConnection *connection , NSURLRequest *request , NSURLResponse *redirectResponse ))block
Parameters
Discussion
Sets a block to be executed when the server redirects the request from one URL to another URL, or when the request URL changed by the NSURLProtocol
subclass handling the request in order to standardize its format, as handled by the NSURLConnectionDelegate
method connection:willSendRequest:redirectResponse:
.
Declared In
AFURLConnectionOperation.h
setShouldExecuteAsBackgroundTaskWithExpirationHandler:
Specifies that the operation should continue execution after the app has entered the background, and the expiration handler for that background task.
- (void)setShouldExecuteAsBackgroundTaskWithExpirationHandler:(void ( ^ ) ( void ))handler
Parameters
- handler
A handler to be called shortly before the application’s remaining background time reaches 0. The handler is wrapped in a block that cancels the operation, and cleans up and marks the end of execution, unlike the
handler
parameter inUIApplication -beginBackgroundTaskWithExpirationHandler:
, which expects this to be done in the handler itself. The handler is called synchronously on the main thread, thus blocking the application’s suspension momentarily while the application is notified.
Discussion
Specifies that the operation should continue execution after the app has entered the background, and the expiration handler for that background task.
Declared In
AFURLConnectionOperation.h
setUploadProgressBlock:
Sets a callback to be called when an undetermined number of bytes have been uploaded to the server.
- (void)setUploadProgressBlock:(void ( ^ ) ( NSUInteger bytesWritten , long long totalBytesWritten , long long totalBytesExpectedToWrite ))block
Parameters
- block
A block object to be called when an undetermined number of bytes have been uploaded to the server. This block has no return value and takes three arguments: the number of bytes written since the last time the upload progress block was called, the total bytes written, and the total bytes expected to be written during the request, as initially determined by the length of the HTTP body. This block may be called multiple times, and will execute on the main thread.
Discussion
Sets a callback to be called when an undetermined number of bytes have been uploaded to the server.
Declared In
AFURLConnectionOperation.h