iOS CallKit Directory Extension Tips


  1. The label text that you see will have the following format: Caller ID:  You can change the app name part of the label by changing app’s Bundle Name.
  2. You must provide a full country code and area code with the phone number.
  3. -reloadExtensionWithIdentifier:completionHandler:, which requests to have your app extension’s data reloaded by the system. Call this whenever you have new blocking or identification data to provide to the system.
  4. -getEnabledStatusForExtensionWithIdentifier:completionHandler:, which allows your app to query whether its extension has been enabled in Settings. Call this from within your app before requesting to reload data, and perhaps prompt the user to first enable your extension in Settings in order to begin loading data.
  5. The array of phone numbers must be a sorted list of int64’s. From smallest to largest. The list will be rejected with an “entries out of order” error otherwise.
  6. Store all the contacts to directory every time, because directory is getting recreated (loosing the previous contacts). Checked in iOS 11.
  7. Make sure the phone numbers are of type NSNumber instead of NSString.

iOS AES128 Encryption and Decryption

Why I am giving the following steps instead of direct link is. The link is changing frequently I guess or they are updating the article or code itself. I saw the method names got changed.

Follow the steps.

  1. Go to
  2. Top left corner, you see search box. Search for Strong Encryption.
  3. Read the article and down the data from the link provided.



kCCOptionECBMode : Electronic Code Book (ECB). Electronic Code Book (ECB) is a mode of operation for a block cipher, with the characteristic that each possible block of plaintext has a defined corresponding ciphertext value and vice versa. In other words, the same plaintext value will always result in the same ciphertext value. Electronic Code Book is used when a volume of plaintext is separated into several blocks of data, each of which is then encrypted independently of other blocks. In fact, Electronic Code Book has the ability to support a separate encryption key for each block type.

Cited the above definition from

CCCrypt is the apple api that actually encrypts or decrypts based on the parameters passed to it.

kCCAlgorithmAES128 is the algorithm to use to encrypt or decrypt. It will successfully encrypt or decrypt only 15 characters, because the buffer size accepts 16 characters. Last character space is for termination character ‘\0’.

If you send more than 15 characters then you will face issue in decryption. So in order to encrypt more than 15 characters then you need to pass kCCOptionECBMode in options. That will internally split the characters and encrypt and provide you the result. In decryption also you mention this mode.

   CCCryptorStatus cryptStatus = CCCrypt( kCCEncrypt, kCCAlgorithmAES128, kCCOptionECBMode + kCCOptionPKCS7Padding,

                                          keyPtr, kCCKeySizeAES256,

                                          NULL /* initialization vector (optional) */,

                                          [self bytes], dataLength, /* input */

                                          buffer, bufferSize, /* output */

                                          &numBytesEncrypted );

Useful Links:


UIPageViewController that has UIPageControl with different dot colours

 Customise page control

  1. Create page control subclassing UIView
  2. Draw the coloured dots in - (void) drawRect:(CGRect) rect
  3. Control the touch events using - (void) touchesBegan:(NSSet *) touches withEvent:(UIEvent *) event
  4. Inform page view controller when user touch it using delegation.

Customise page view controller

  1. Override - (void) viewDidLayoutSubviews and search all the subviews and find the UIPageControl instance.
  2. Hide the UIPageControl instance and add the custom page control instance to its superview.
  3. Set the UIPageControl instance frame to custom page control.
  4. Bring the custom page control using [self.view bringSubviewToFront:pageControl];
  5. When custom page control informs you about the user touch then call the method - (void)setViewControllers:(nullable NSArray *)viewControllers direction:(UIPageViewControllerNavigationDirection)direction animated:(BOOL)animated completion:(void (^ __nullable)(BOOL finished))completion; to move to right or left page.

Page view controller delegate

  1. Update custom control page dots/index using
    - (void) pageViewController:(COPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *) previousViewControllers transitionCompleted:(BOOL) completed
  2. This method - (void) pageViewController:(COPageViewController *)pageViewController willTransitionToViewControllers:(NSArray *) pendingViewControllers will start when user swipes the page. What I did is maintained a variable that tells whether the page is still in transition, based on that I will allow the user interaction with custom page control.


Present notification from foreground

iOS 10 adds the UNUserNotificationCenterDelegate protocol for handling notifications while your app is in the foreground.

- (void) userNotificationCenter:(UNUserNotificationCenter *) center
willPresentNotification:(UNNotification *) notification
withCompletionHandler:(void (^)(UNNotificationPresentationOptions options)) completionHandler
NSLog(@"Present notification from foreground");
completionHandler(UNNotificationPresentationOptionAlert + UNNotificationPresentationOptionSound);

iOS App Transport Security – Enforced from 2017 for Apple app submissions

The ATS requirement is here.
(Section NSAppTransportSecurity)

In summary, below is what we need to do in the apps

1. Make every URLs to https
2. Ensure the TLS version is TLS1.2.
3. Have the certificate used in the server to client communication is trusted.

How do we detect if a URL is ATS compliant?

The nscurl tool on OS X El Capitan supports diagnosing ATS secure connections.

For example, /usr/bin/nscurl –ats-diagnostics will display ATS connection information for Run /usr/bin/nscurl -h for more information.

This tools prints PASS / FAIL information. Ensure PASS results for test with diagnose dictionary with NO exceptions specified.

To view the certificate info of a particular Domain or test out the connection, TLS tool will be a good utility.

Does it affect Socket communication?

Below is the answer from Apple staff (

Right now ATS is only enforced by our high-level APIs (NSURLSession, NSURLConnection, and anything layered on top of those), and there’s been no announcements about that changing.

Keep in mind, however, that ATS’s enhanced security requirements are not arbitrary; they are defined to give your users a good level of security on an increasingly hostile Internet. As such, your app should aim to comply with these requirements even if ATS is not actively enforcing them.

Using C++ to access file from Documents folder on iOS and Print the contents

void printFileInfo()

char *home = getenv(“HOME”);
char *subdir = “/Documents”;

std::stringstream ss;
ss << home << subdir << “/file.txt”;
std::string s = ss.str();

s.erase(0, strlen(“/private”)); // Erase “/Private” from the final string

char sss;

char letter ;
int i ;
std::string line ;

std::ifstream reader(s.c_str()) ;

if (!reader) {

std::cout << “Error opening input file” << std::endl ;
return -1 ;


for (i = 0; !reader.eof() ; i++) {

getline( reader , line ) ;
std::cout << s.c_str() << std::endl;
std::cout << line << std::endl ;

reader.close() ;


iPv6 Network not available issue

+ (instancetype)  reachabilityForInternetConnection

Reachability *reach = NULL;
NetworkStatus status = NotReachable;

struct sockaddr_in zeroAddress;
bzero(&zeroAddress, sizeof(zeroAddress));
zeroAddress.sin_len = sizeof(zeroAddress);
zeroAddress.sin_family = AF_INET;

reach = [self reachabilityWithAddress: (const struct sockaddr *) &zeroAddress];

if  (reach != NULL)

status = [reach currentReachabilityStatus];

if (status != NotReachable)

NSLog(@”Connected to Ipv4 Environment”);

return reach;



if  ([[UIDevice currentDevice].systemVersion floatValue] < 9.0)

// check whether you are in iPv6 environment

struct sockaddr_in6 zeroAddress1;
bzero(&zeroAddress1, sizeof(zeroAddress1));
zeroAddress1.sin6_len = sizeof(zeroAddress1);
zeroAddress1.sin6_family = AF_INET6;

reach = [self reachabilityWithAddress: (const struct sockaddr *) &zeroAddress1];

if  (reach != NULL)

status = [reach currentReachabilityStatus];

if (status != NotReachable)

NSLog(@”Connected to Ipv6 Environment”);




return reach;