Objective C: SSL Pining - objective-c

Question

I have implement NSURLConnectionDataDelegate in my class and I have implemented the method:
- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge;
But when I make new NSURLConnection this method isn't called. Why? Where is the problem? The connections is an SSL connection.
I have look inside an example project downloaded by internet (I don't remember where) and this project work fine, but if I do the some step in my project don't work. I need any external library or to set something in the proj? You can suggest me a for-dummies guide?
Edit 1:
In the example I use:
NSURL *httpsURL = [NSURL URLWithString:#"https://secure.skabber.com/json/"];
NSURLRequest *request2 = [NSURLRequest requestWithURL:httpsURL cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:15.0f];
NSURLConnection *connection = [NSURLConnection connectionWithRequest:request2 delegate:self];
[connection start];
But I want to work with any kind of NSURLConnection.
Edit 2:
This is my complete code:
#interface ConnectionDelegate : NSObject<NSURLConnectionDataDelegate>
#property (strong, nonatomic) NSURLConnection *connection;
#property (strong, nonatomic) NSMutableData *responseData;
- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge;
-(void)testHTTPRequest;
#end
#implementation ConnectionDelegate
-(void)testHTTPRequest
{
NSURL *httpsURL = [NSURL URLWithString:#"https://secure.skabber.com/json/"];
NSURLRequest *request = [NSURLRequest requestWithURL:httpsURL cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:15.0f];
self.connection = [NSURLConnection connectionWithRequest:request delegate:self];
[self.connection start];
if ([self isSSLPinning]) {
[self printMessage:#"Making pinned request"];
}
else {
[self printMessage:#"Making non-pinned request"];
}
}
- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
SecTrustRef serverTrust = challenge.protectionSpace.serverTrust;
SecCertificateRef certificate = SecTrustGetCertificateAtIndex(serverTrust, 0);
NSData *remoteCertificateData = CFBridgingRelease(SecCertificateCopyData(certificate));
NSData *skabberCertData = [self skabberCert];
if ([remoteCertificateData isEqualToData:skabberCertData] || [self isSSLPinning] == NO) {
if ([self isSSLPinning] || [remoteCertificateData isEqualToData:skabberCertData]) {
[self printMessage:#"The server's certificate is the valid secure.skabber.com certificate. Allowing the request."];
}
else {
[self printMessage:#"The server's certificate does not match secure.skabber.com. Continuing anyway."];
}
NSURLCredential *credential = [NSURLCredential credentialForTrust:serverTrust];
[[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
}
else {
[self printMessage:#"The server's certificate does not match secure.skabber.com. Canceling the request."];
[[challenge sender] cancelAuthenticationChallenge:challenge];
}
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
if (self.responseData == nil) {
self.responseData = [NSMutableData dataWithData:data];
}
else {
[self.responseData appendData:data];
}
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *response = [[NSString alloc] initWithData:self.responseData encoding:NSUTF8StringEncoding];
[self printMessage:response];
self.responseData = nil;
}
- (NSData *)skabberCert
{
NSString *cerPath = [[NSBundle mainBundle] pathForResource:#"secure.skabber.com" ofType:#"cer"];
return [NSData dataWithContentsOfFile:cerPath];
}
- (void)printMessage:(NSString *)message
{
Log(#"%#",message);
}
- (BOOL)isSSLPinning
{
NSString *envValue = [[[NSProcessInfo processInfo] environment] objectForKey:#"SSL_PINNING"];
return [envValue boolValue];
}
#end
If i put a breakpoint on connection:willSendRequestForAuthenticationChallenge: the program don't enter in it.