viewDidLoad not being called in Swift subclasses inherited from Objc superclass - objective-c

Question

I have a question about viewDidLoad in Objc versus Swift. I am not
familiar with Swift, and I'm trying to embed Swift code into our app for the first time.
The swift code I am trying to embed has two classes with inheritance declared this way:
ViewController_A (swift) : ViewController_B (swift) : UIViewController
Both view controllers A and B have "overriding" viewDidLoad methods.
That is they are declared as override func viewDidLoad() {}. If
I leave the above relationship as is and I run with breakpoints set and
print statements in viewDidLoad of both ViewController_A and ViewController_B,
I do see that viewDidLoad for ViewController_A executes before viewDidLoad for
viewController_B. That seems to make perfect sense. Both respective
viewDidLoad methods call super.viewDidLoad. All is good.
I tried to change the inheritance of the above hierarchy by adding an
Objective-C class in the chain:
ViewContoller_A (Swift) : ViewController_B (Swift) : ViewController_C (Objective-C) : UIViewController.
ViewController_C also has a viewDidLoad method which also calls [super viewDidLoad].
If I run with breakpoints set and prints/NSLog at the beginning of all three viewDidLoad methods in all three view controllers, only viewDidLoad for ViewController_C (Objective-C)
executes. The breakpoints/prints in controllers A and B viewDidLoad never appear. I'm not sure this is adding unnecessary info to the topic, but what's interesting is I'll get a warning message:
Attempt to present ViewController_A on ViewController_C whose view is not in the
window hierarchy!
This seems to be telling me that something about ViewController_A is trying to load the view. So just to be sure, as a test, I commented out all the UI related code in ViewContoller_C viewDidLoad. I do not then get that warning message, and it shouldn't prevent ViewController_A viewDidLoad to execute, but the viewDidLoad method in ViewController_A still does not.
Note, ViewController_C is being brought up by a modal storyboard segue, if that adds any relevant info.
So sorry for all that rambling, but is there a way to force the viewDidLoad methods in the Swift subclass view controllers to be executed in the class inheritance hierarchy I outlined above with the Objective-C view controller added to the mix?
Thank you for your help,
Mike
Thank you for your replies. I've added some code below for your review. If I can add anything else, please let me know. Maybe a brief overview will help.
Our App's code set that I've added represents a barcode scanning controller we use to read barcode tags from sample vials. That code is in objc. A customer would like now to read a text code in the same operational context. So in the short term I'm chopping up the barcode scanning controller to get things started.
For this project I brought in a sample app written by Apple available for download from one of their WWDC sessions for reading/recognizing phone numbers. That's the code written in swift. I've made minor modifications to this code so far.
Once the technical hurdles are overcome, I will be re-writing both.
Beginning of BarCodeScan .h and .m files:
#ifndef _BARCODESCANNERCONTROLLER_H_
#define _BARCODESCANNERCONTROLLER_H_
#import <UIKit/UIKit.h>
#import "SystemHeader.h"
#import "RunParameters.h"
#import <RDPDFKit/RDPDFKit.h>
#import "FormInfo.h"
#import "PatientInfo.h"
#import "GradientButton.h"
#import "LogTextInfo.h"
#import "FileIOSupport.h"
#import "PadInfo.h"
#import "XMLiPadAndDBSupport.h"
#import "BarCodeScanSupport.h"
#import "LogonInfo.h"
#import "PadInfo.h" // ocr
#import "TextScanPreviewView.h" // ocr
#define YesIndex 0
//
// With PDF coordintates, pixels are spot on so no shift
// is needed. Keep these at 0 for now.
//
#define SCALE_Y_ADJUSTMENT_FACTOR 0
#define SCALE_X_ADJUSTMENT_FACTOR 0
#define XML_VERSION_STR "<?xml version=\"1.0\"?>"
#define XML_HEADER_NAME "IFD"
#define ResultCount "ResultCount"
#define Result "Result"
#define DoNotCheck #"DoNotCheck"
#define DoNotValidate #"DoNotValidate"
//
// These enums are for determining the action needed when
// an incorrect but valid bar code is scanned.
//
//
// These enums are for determining the action needed when
// an incorrect but valid bar code is scanned.
//
typedef enum IncorrectBarCodeStatusEnum
{
BCNotRecognized = 1,
BCNotUsedButBelongsToAnotherForm,
BCAlreadyUsedByAnotherForm,
BCIsOK
} IncorrectBarCodeStatusEnum;
#interface ReturnResultBarCodeStatus : NSObject
#property (strong, nonatomic) FormInfo * formWhereBarCodeFound;
#property (assign, nonatomic) IncorrectBarCodeStatusEnum incorrectBarCodeStatus;
#end
#interface BarCodeScanController : UIViewController <UIAlertViewDelegate> // Merck2
{
BOOL isScanModeOn;
UIColor *borderColorDefault;
UIColor *viewBackgroundColorDefault;
CGPoint lineStartingPoint;
CGPoint lineEndingPoint;
int barCodeImageViewUpperYCoordinate;
DecoderResult * decoder;
// ocr
NSString * textScanResult;
}
//
// This contains this page's pixel values that are read
// from the xml incoming DBToPad file.
//
#property (strong, nonatomic) Barcode * barCode;
#property (strong, nonatomic) PatientInfo * patient;
#property (strong, nonatomic) FormInfo * form;
#property (strong, atomic) PadInfo * pad;
#property (strong, atomic) LogonInfo * logon;
#property (strong, nonatomic) RDPDFDocument * pdfDocument;
#property (strong, nonatomic) RDPDFDocumentView *pdfDocumentView;
#property (strong, nonatomic) IBOutlet UIImageView * barCodeImageView;
#property (strong, nonatomic) IBOutlet TextScanPreviewView * previewView3;
#property (strong, nonatomic) IBOutlet UIView * cutoutView;
#property (weak, nonatomic) IBOutlet GradientButton *submitButton;
- (IBAction)submitButtonAction:(GradientButton *)sender;
#property (weak, nonatomic) IBOutlet GradientButton *cancelButton;
- (IBAction)cancelButtonAction:(GradientButton *)sender;
#property (weak, nonatomic) IBOutlet GradientButton *scanButton;
- (IBAction)scanButtonAction:(GradientButton *)sender;
#property (weak, nonatomic) IBOutlet UILabel *formLabel;
#property (weak, nonatomic) IBOutlet UILabel *barCodeResultLabel;
#property (strong, nonatomic) BarCodeScanSupport *barCodeScanner;
#property (strong, nonatomic) NSMutableArray *uniqueBarCodes;
- (void) writeBarCodeResultsToXMLDataFile : (BOOL) dataFlag;
- (void) determineIncorrectBarCodeCase
: (NSString *) barCodeResult
: (ReturnResultBarCodeStatus *) returnStatus;
- (void) continueDecodeResultNotification;
#end
#endif
`````` Controller "C"
#import "BarCodeScanController.h"
#implementation ReturnResultBarCodeStatus
#synthesize formWhereBarCodeFound;
#synthesize incorrectBarCodeStatus;
#end
#implementation BarCodeScanController : UIViewController
#synthesize barCode;
#synthesize form;
#synthesize pad;
#synthesize logon;
#synthesize submitButton;
#synthesize cancelButton;
#synthesize scanButton;
#synthesize barCodeImageView;
#synthesize previewView3;
#synthesize cutoutView;
#synthesize pdfDocument;
#synthesize pdfDocumentView;
#synthesize barCodeScanner;
#synthesize uniqueBarCodes;
#synthesize barCodeResultLabel;
#synthesize formLabel;
//
// This is temporary for the demo. Should read whats in the file
// if we scanned on a page, srolled to another, and came back to
// the scanned page. But for now, just .
//
static NSString * saveBarCodeResult;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[NSThread sleepForTimeInterval : 2.0];
[super viewDidLoad];
if (deviceIsIPad)
{
self.formLabel.text = [NSString stringWithFormat:
#"%#",form.form];
}
else
{
self.formLabel.text = [NSString stringWithFormat:
#" %#",form.form];
}
[self.cancelButton useAlertStyle];
[self.submitButton useAlertStyle];
[self.scanButton useAlertStyle];
if (self.form.displaySubmitButton == NO)
{
self.submitButton.hidden = YES;
}
else
{
self.submitButton.hidden = NO;
}
//
// This creates an .ifd file with no data in it. The data base server requires
// a file with valid data or null data for each vas page. So if the user
// evenutally enters valid data, it will overwrite this. Creating the file here
// is completely dependent on the user having to scroll to the end of the form
// to do a submit. In doing so, every vas page must be passed along the way
// which will initiate this call. If we ever go back to starting out with a
// submit button on every page when the form is brought up, then we will have
// to create a null .ifd file in the forms modal controller, which will mean
// we will have to have duplicate functionality in both that controller and
// this one. Note, later added code made sure file does not first exist. It
// may already be there if there was a crash during the submit. In this case
// don't write a null file, and set vsLineDrawn to YES.
//
//
FileIOSupport * sandbox = [[FileIOSupport alloc] init];
if (![sandbox checkIfFileExistsAtPath : self.barCode.bcPngPathNameData])
{
[self writeBarCodeResultsToXMLDataFile : NO];
}
[[NSNotificationCenter defaultCenter] addObserver: self selector:#selector(decodeResultNotification:) name: BarCodeResultNotification object: nil];
// ocr x
// Comment out for text reader.
// barCodeScanner = [[BarCodeScanSupport alloc] init : barCodeImageView : self
// : self.barCode.bcFormat];
// ocr x
// Comment out for text reader
// self.barCodeImageView.image = [UIImage imageWithContentsOfFile :
// barCode.bcPngPathNameImage];
[scanButton setTitle:Retry_Str forState:UIControlStateNormal];
//
// Setting isScanModeOn works for both cases below. If we have a prior
// result we don't start the scanner but put up the previous result and
// image. If there is no prior result, we call the scanButtonAction code
// to start the scanner.
//
isScanModeOn = NO;
if (self.barCode.bcImageBuffer != nil)
{
self.barCodeResultLabel.hidden = NO;
self.barCodeResultLabel.text = barCode.bcSelectedResult;
self.barCodeResultLabel.backgroundColor = [UIColor yellowColor];
}
else
{
self.barCodeResultLabel.hidden = YES;
self.barCodeResultLabel.text = Blank;
//
// Start scanner
//
[self scanButtonAction : scanButton];
}
// ocr
// This normally gets allocatd in bar code scanner support which we are not
// using for ocr. So allocate it here. We're only using the text part of it
// so as to not disturb alot of code.
//
decoder = [DecoderResult alloc];
// ocr
// Comment out for text reader
// barCodeImageViewUpperYCoordinate = self.barCodeImageView.frame.origin.y;
DISPATCH_TO_MAIN_THREAD
// ocr x
// Comment out for text reader
// [self startScanning];
// [self performSegueWithIdentifier:TextReaderModalSegue sender:self];
DISPATCH_OUT_OF_MAIN_THREAD
}
.
.
.
Contents of Project-Bridging-Header.h
// ocr
#import "ObjectiveCTestWithSwift.h"
#import "BarCodeScanController.h"
#import "TextScanPreviewView.h"
One of Apple's controllers - Controller "B". Note I tried viewDidLoad
with "public" keyword and without.
import UIKit
import AVFoundation
import Vision
// ocr
// class TextReaderViewController: UIViewController {
class TextReaderViewController : BarCodeScanController {
// MARK: - UI objects
//
// ocr
// Comment these out. These outlets will be provided by barcodescancontroller.
// #IBOutlet weak var cutoutView: UIView!
// #IBOutlet weak var previewView: PreviewView!
#IBOutlet weak var numberView: UILabel!
var maskLayer = CAShapeLayer()
// Device orientation. Updated whenever the orientation changes to a
// different supported orientation.
var currentOrientation = UIDeviceOrientation.portrait
// MARK: - Capture related objects
private let captureSession = AVCaptureSession()
let captureSessionQueue = DispatchQueue(label: "com.example.apple-samplecode.CaptureSessionQueue")
var captureDevice: AVCaptureDevice?
var videoDataOutput = AVCaptureVideoDataOutput()
let videoDataOutputQueue = DispatchQueue(label: "com.example.apple-samplecode.VideoDataOutputQueue")
// MARK: - Region of interest (ROI) and text orientation
// Region of video data output buffer that recognition should be run on.
// Gets recalculated once the bounds of the preview layer are known.
var regionOfInterest = CGRect(x: 0, y: 0, width: 1, height: 1)
// Orientation of text to search for in the region of interest.
var textOrientation = CGImagePropertyOrientation.up
// MARK: - Coordinate transforms
var bufferAspectRatio: Double!
// Transform from UI orientation to buffer orientation.
var uiRotationTransform = CGAffineTransform.identity
// Transform bottom-left coordinates to top-left.
var bottomToTopTransform = CGAffineTransform(scaleX: 1, y: -1).translatedBy(x: 0, y: -1)
// Transform coordinates in ROI to global coordinates (still normalized).
var roiToGlobalTransform = CGAffineTransform.identity
// Vision -> AVF coordinate transform.
var visionToAVFTransform = CGAffineTransform.identity
// MARK: - View controller methods
// ocr
public override func viewDidLoad() {
// ocr
print("viewDidLoad TextReaderViewController")
// ocr x
super.viewDidLoad()
// Set up preview view.
previewView3.session = captureSession
// Set up cutout view.
cutoutView.backgroundColor = UIColor.gray.withAlphaComponent(0.5)
maskLayer.backgroundColor = UIColor.clear.cgColor
maskLayer.fillRule = .evenOdd
cutoutView.layer.mask = maskLayer
// Starting the capture session is a blocking call. Perform setup using
// a dedicated serial dispatch queue to prevent blocking the main thread.
captureSessionQueue.async {
self.setupCamera()
// Calculate region of interest now that the camera is setup.
DispatchQueue.main.async {
// Figure out initial ROI.
self.calculateRegionOfInterest()
}
}
// ocr
// super.viewDidLoad()
}
.
.
.
2nd of Apples Controller "A". Note I tried viewDidLoad
with "public" keyword and without.
import Foundation
import UIKit
import AVFoundation
import Vision
// ocr
// class VisionViewController: ViewController {
class VisionViewController: TextReaderViewController {
var request: VNRecognizeTextRequest!
// Temporal string tracker
let numberTracker = StringTracker()
public override func viewDidLoad() {
// Set up vision request before letting ViewController set up the camera
// so that it exists when the first buffer is received.
// ocr
print("viewDidLoad VisionViewController")
request = VNRecognizeTextRequest(completionHandler: recognizeTextHandler)
super.viewDidLoad()
}
.
.
.

Answer 1

in
#interface BarCodeScanController : UIViewController
// place a definition, so swift (Xcode) can see it.
-(void)viewDidLoad;
#end

Answer 2

I discovered my perform segue was executing the wrong view controller. Once I corrected that, the viewDidLoad's executed in the correct sequence.