The document discusses the implementation of networking in iOS development, focusing on the use of NSURLConnection and the AFNetworking library for handling network requests. It highlights the complexities of using NSURLConnection directly compared to the more user-friendly AFNetworking, which simplifies the process of making asynchronous HTTP requests and handling JSON responses. Additionally, it covers concepts related to custom serialization and the organization of network operations within an NSOperationQueue.

1. Working With
AFNetworking
@waynehartman

2. Before AFNetworking
• NSURLConnection (meh)
• NSData (BARF!)
• CFNetwork (medic!)

3. NSURLConnection - (IBAction)didSelectRefreshButton:(id)sender {
NSURL *url = [NSURL URLWithString:@"http://ip.jsontest.com/"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
!
self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
}
!
#pragma mark - NSURLConnection
!
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response {
_data = nil;
!
switch (response.statusCode) {
case 200: {
self.data = [NSMutableData dataWithCapacity:(NSUInteger)response.expectedContentLength];
}
break;
default: {
[connection cancel];
!
NSError *error = [NSError errorWithDomain:(NSString *)kCFErrorDomainCFNetwork
code:response.statusCode
userInfo:@{(NSString *)kCFErrorDescriptionKey : (NSString *)kCFURLErrorFailingURLErrorKey}];
[self connection:connection didFailWithError:error];
}
break;
}
}
!
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[self.data appendData:data];
}
!
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSError *error = nil;
NSDictionary *jsonData = [NSJSONSerialization JSONObjectWithData:self.data options:0 error:&error];
if (!jsonData) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"The data was corrupt. Sorry"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
} else {
NSString *ip = jsonData[@"ip"];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success!"
message:[NSString stringWithFormat:@"Your IP is: %@", ip]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
!
self.connection = nil;
}
!
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"There was an error getting the data. Please try again later."
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
self.connection = nil;
}
• All this code, just to download
and display this:
{"ip": "72.191.49.142"}

4. NSData
• One line of code!
!
dataWithContentsOfURL:
!
NEVER USE THIS API!

5. CFNetwork NSURL *url = [NSURL URLWithString:DOWNLOAD_URL];
!
CFHTTPMessageRef request = CFHTTPMessageCreateRequest(NULL, CFSTR("GET"), (__bridge CFURLRef)url, kCFHTTPVersion1_1);
!
CFReadStreamRef requestStream = CFReadStreamCreateForHTTPRequest(NULL, request);
CFReadStreamOpen(requestStream);
NSMutableData *responseBytes = [NSMutableData data];
CFIndex numBytesRead = 0 ;
NSUInteger totalBytesRead = 0;
!
do {
UInt8 buf[1024];
numBytesRead = CFReadStreamRead(requestStream, buf, sizeof(buf));
if(numBytesRead > 0) {
[responseBytes appendBytes:buf length:numBytesRead];
totalBytesRead += numBytesRead;
}
} while(numBytesRead > 0);
if (totalBytesRead > 0) {
CFHTTPMessageRef response = (CFHTTPMessageRef)CFReadStreamCopyProperty(requestStream, kCFStreamPropertyHTTPResponseHeader);
CFHTTPMessageSetBody(response, (__bridge CFDataRef)responseBytes);
CFReadStreamClose(requestStream);
CFDataRef responseBodyData = CFHTTPMessageCopyBody(response);
NSError *error = nil;
NSDictionary *jsonData = [NSJSONSerialization JSONObjectWithData:(__bridge NSData *)responseBodyData options:0 error:&error];
CFRelease(responseBodyData);
CFRelease(response);
if (!jsonData) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"The data was corrupt. Sorry"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
} else {
NSString *ip = jsonData[@"ip"];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success!"
message:[NSString stringWithFormat:@"Your IP is: %@", ip]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"There was an error getting the data. Please try again later."
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
!
CFRelease(requestStream);
CFRelease(request);
• All this code, just to download
and display this:
{"ip": "72.191.49.142"}
• Plus we have to write gross C
with nasty CFRelease()

6. AFNetworking
“AFNetworking is a delightful networking library for iOS and Mac OS
X. It's built on top of the Foundation URL Loading System, extending
the powerful high-level networking abstractions built into Cocoa. It
has a modular architecture with well-designed, feature-rich APIs that
are a joy to use.”

7. AFNetworking
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:DOWNLOAD_URL]];
!
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[operation setResponseSerializer:[AFJSONResponseSerializer serializer]];
[operation setCompletionBlockWithSuccess:successHandler failure:failureHandler];
!
[operation start];

8. AFNetworking
void(^failureHandler)(AFHTTPRequestOperation *, NSError *) = ^(AFHTTPRequestOperation *operation, NSError *error) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"There was an error getting the data. Please try again later."
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
};

9. AFNetworking
void(^successHandler)(AFHTTPRequestOperation *, id) = ^(AFHTTPRequestOperation *operation, id responseObject) {
if (!responseObject) {
failureHandler(operation, [NSError errorWithDomain:AFNetworkingErrorDomain code:404 userInfo:nil]);
} else {
NSString *ip = responseObject[@"ip"];
!
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success!"
message:[NSString stringWithFormat:@"Your IP is: %@", ip]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
};

10. void(^failureHandler)(AFHTTPRequestOperation *, NSError *) = ^(AFHTTPRequestOperation *operation, NSError *error) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"There was an error getting the data. Please try again later."
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
};
void(^successHandler)(AFHTTPRequestOperation *, id) = ^(AFHTTPRequestOperation *operation, id responseObject) {
if (!responseObject) {
failureHandler(operation, [NSError errorWithDomain:AFNetworkingErrorDomain code:404 userInfo:nil]);
} else {
NSString *ip = responseObject[@"ip"];
!
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success!"
message:[NSString stringWithFormat:@"Your IP is: %@", ip]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
};
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:DOWNLOAD_URL]];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[operation setResponseSerializer:[AFJSONResponseSerializer serializer]];
[operation setCompletionBlockWithSuccess:successHandler failure:failureHandler];
!
[operation start];
- (IBAction)didSelectRefreshButton:(id)sender {
NSURL *url = [NSURL URLWithString:@"http://ip.jsontest.com/"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
!
self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
}
!
#pragma mark - NSURLConnection
!
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response {
_data = nil;
!
switch (response.statusCode) {
case 200: {
self.data = [NSMutableData dataWithCapacity:(NSUInteger)response.expectedContentLength];
}
break;
default: {
[connection cancel];
!
NSError *error = [NSError errorWithDomain:(NSString *)kCFErrorDomainCFNetwork
code:response.statusCode
userInfo:@{(NSString *)kCFErrorDescriptionKey : (NSString *)kCFURLErrorFailingURLErrorKey}];
[self connection:connection didFailWithError:error];
}
break;
}
}
!
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[self.data appendData:data];
}
!
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSError *error = nil;
NSDictionary *jsonData = [NSJSONSerialization JSONObjectWithData:self.data options:0 error:&error];
if (!jsonData) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"The data was corrupt. Sorry"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
} else {
NSString *ip = jsonData[@"ip"];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success!"
message:[NSString stringWithFormat:@"Your IP is: %@", ip]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
!
self.connection = nil;
}
!
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"There was an error getting the data. Please try again later."
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
self.connection = nil;
}

12. Key Concepts
• AF*Operation are subclasses of NSOperation
• Networking operations can be started individually or placed in an
NSOperationQueue
• Custom serialization classes can be created for transforming and
validating data.

13. Demo: Using Queues

14. AFURLResponseSerializer
• If you don’t specify a request/response serializer, it will give back
NSData.
• Serializers can be created to handle data transformation and
validation.

15. AFURLResponseSerializer
AFJSONResponseSerializer
AFPropertyListResponseSerializer
AFImageResponseSerializer
AFCompoundResponseSerializer
AFXMLParserResponseSerializer
!
AFXMLDocumentResponseSerializer

16. Custom Serializer
• Subclass AFHTTPResponseSerializer
• Override
• responseObjectForResponse:data:error:
• acceptableContentTypes

17. Custom Serializer
• We’re going to create a serializer for decoding 1337593@k

18. Anyone know the Content-Type for
1337 encoded data?

19. @99l1c@710n/l337

20. D3m0: Cu570m R3590n53
53r1@l1z@710n

21. AFNetworking + UIKit
• AFNetworking adds a number of extensions to common UIKit
classes:
• UIImageView
• UIButton
• UIWebView
• UIProgressView
• UIRefreshControl

22. Demo: UIKit Extensions

23. Design Patterns for
Network & Data

24. “At its heart, programming is all
about abstraction.”
Justin Spahr-Summers
CocoaConf Austin 2014

25. Classes should have as few purposes as possible (say, one)
and do it very well.
!
Classes should know as little as possible about other classes.

26. Are your View Controllers like this?

27. Case Study:
Geekdom for iOS

29. Monster View Controller
• UITableView Datasource
• Configure Cells
• UITableView Delegate
• Showing Member Details
• NSFetchedResultsControllerDelegate
• Fetch All Member data
• Fetch Checked-In Members
• Fetch Profile Images
• Search Members By Name
• Search Members By Skills
• Data Persistance
• Check-In logic
• Checked-In vs All Members

32. Questions?

33. @waynehartman