iOS 9 Making Code go Sequentially (Touch ID) - ios

Question

I am a developer using self-taught Objective-C to code for the iPhone. We are using Xcode 7 and iOS 9. I am tasked with creating an app for my company to communicate when someone arrives and leaves an appointment in a schedule made for them (using XML).
We would like to use Touch ID for security so the users don’t have to log in a lot. Security is required because of the confidentiality of the data in the app. I had the application working. Or it looked like it worked, until I clicked on the Cancel option in Touch ID and realized that the Touch ID was providing no security.
I believe this is because the methods that are supposed to run after Touch ID were outside of the LA Context block. I put them outside because I need to return a string value on a successful authorization (an internal employee number retrieved through XML). If I put the methods with the returned NSStrings outside of the LA Context block, the methods run in the wrong order.
How can I make the following 4 methods run in sequential order?
1)requireLogin (Touch ID code here)
2)requestSession
3)readSession
4)checkSession
If the Touch ID fails, methods 2-4 should not run.
I’ve looked at blocks. I’ve looked at GCD. I can’t find any examples on how to deal with this. If someone could point me in the right direction. I would really appreciate it. If I need to include more of the code, please let me know.
Thank you in advance.
- (NSString *)retrieveESN {
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [directoryPaths objectAtIndex:0];
NSString *fullPath = [documentsDirectoryPath stringByAppendingString:#"/session.txt"];
if ([fileManager fileExistsAtPath:fullPath]==YES) {
_finished = false;
NSLog(#"File exists");
[self readSession];
NSLog(#"%#", _sessionDetail);
NSLog(#"Pre Check Session");
NSString *result = [self checkSession:_sessionDetail];
NSLog(#"Post Check Session");
NSLog(#"%#", result);
if ([result isEqualToString:#"Error"]) {
NSLog(#"Error received - going into newFile");
NSString *userESN = [self newFile];
NSLog(#"Error'd returning with result");
NSLog(#"UserESN: %#", userESN);
return userESN;
} else {
NSLog(#"No Error Received");
NSLog(#"Returning result: %#", result);
return result;
}
} else {
_finished = false;
NSLog(#"No file exists, call newFile");
NSString *userESN = [self newFile];
NSLog(#"UserESN: %#", userESN);
return userESN;
}
}
- (NSString *)newFile {
NSLog(#"File does not exist.");
[self requireLogin];
NSLog(#"Out of requireLogin");
[self requestSession];
NSLog(#"Out of requestSession");
[self readSession];
NSLog(#"Out of readSession");
NSString *userESN = [self checkSession:_sessionDetail];
NSLog(#"Into checkSession again newfile");
return userESN;
}
- (void)requireLogin {
LAContext *context = [[LAContext alloc] init];
NSError *error = nil;
NSLog(#"Into requireLogin");
if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
// Authenticate User
[context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
localizedReason:#"You must log in to the app."
reply:^(BOOL success, NSError * _Nullable error) {
if (success) {
_finished = true;
NSLog(#"success");
} else {
switch (error.code) {
case LAErrorAuthenticationFailed:
NSLog(#"Authentication Failed");
break;
case LAErrorUserCancel:
NSLog(#"User pressed Cancel button");
break;
case LAErrorUserFallback:
//Return to go to Enter Password not available screen.
NSLog(#"User pressed Enter Password");
break;
default:
NSLog(#"Touch ID is not configured");
break;
}
NSLog(#"Authentication Fails");
}
}];
} else {
NSLog(#"Phone doesn't support Touch ID.");
}
}
- (void)requestSession {
NSString *idfv = [[[UIDevice currentDevice] identifierForVendor] UUIDString];
NSString *url = #“https://companyurl.com/session_page”;
NSLog(#"Got to requestSession");
NSMutableString *postText = [[NSMutableString alloc] init];
NSLog(#"%#", idfv);
[postText appendString:idfv];
NSString *postBody = [NSString stringWithString:postText];
XMLPostSecurity *postAction = [[XMLPostSecurity alloc] init];
NSLog(#"Got to PostAction");
_sessionDetail = [postAction sendPostRequestToUrl:url withBody:postBody];
NSLog(#"Session Detail: %#", _sessionDetail);
FileSaving *saver = [[FileSaving alloc] init];
[saver saveSession:self.sessionDetail];
NSLog(#"Saved file.");
}
-(NSString *)readSession {
NSLog(#"In to readSession.");
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [directoryPaths objectAtIndex:0];
NSString *fullPath = [documentsDirectoryPath stringByAppendingString:#"/session.txt"];
while ([fileManager fileExistsAtPath:fullPath]==NO);
NSFileManager *fileManagerTwo;
NSData *dataBuffer;
fileManagerTwo = [NSFileManager defaultManager];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingString:#"/session.txt"];
NSLog(#"Got Path");
dataBuffer = [fileManagerTwo contentsAtPath:filePath];
NSLog(#"databuffer created");
_sessionDetail = [[NSString alloc] initWithData:dataBuffer encoding:(NSASCIIStringEncoding)];
NSLog(#"File read: %#", _sessionDetail);
return _sessionDetail;
}
-(NSString *)checkSession:(NSString *)sessionFound {
NSLog(#"Into checkSession");
NSDictionary *cookieProperties = [NSDictionary dictionaryWithObjectsAndKeys:
#"ollie/", NSHTTPCookieDomain,
#"\\", NSHTTPCookiePath,
#"cookieName", NSHTTPCookieName,
sessionFound, NSHTTPCookieValue,
nil];
NSHTTPCookie *cookie = [NSHTTPCookie cookieWithProperties:cookieProperties];
NSArray *cookieArray = [NSArray arrayWithObject:cookie];
NSDictionary *headers = [NSHTTPCookie requestHeaderFieldsWithCookies:cookieArray];
NSMutableString *url = [[NSMutableString alloc] initWithString:#“https://companyurl.com/xmlfile.php”];
NSLog(#"%#", url);
NSURL *urlNew = [NSURL URLWithString:url];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:urlNew];
[request setHTTPMethod:#"GET"];
[request setAllHTTPHeaderFields:headers];
self.parseData = NULL;
NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:request
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
if (error) {
NSLog(#"dataTaskWithRequest error: %#", error);
return;
}
if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
NSInteger statusCode = [(NSHTTPURLResponse *)response statusCode];
if (statusCode != 200) {
NSLog(#"dataTaskWithRequest HTTP status code: %ld", (long)statusCode);
if (statusCode == 401) {
// Insert process for thumbprint and session cookie pull
NSLog(#"401 Error received");
NSFileManager *fileManagerThree = [NSFileManager defaultManager];
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *sessionPath = [documentsPath stringByAppendingPathComponent:#"session.txt"];
NSError *error;
BOOL success = [fileManagerThree removeItemAtPath:sessionPath error:&error];
if (success) {
NSLog(#"File deleted - check session.");
} else {
NSLog(#"File could not be deleted.");
}
} else {
NSLog(#"I got something other than 200 or 401");
return;
}
}
}
self.parseData = data;
}];
[task resume];
while ( self.parseData == NULL );
ParseTypeXML *myParser = [[ParseTypeXML alloc] initWithData:self.parseData];
if ([myParser.esn count] == 0) {
return #"Error";
} else {
return myParser.esn[0];
}
}