Access an Objective C dictionary from an Objective C ViewController in a Swift ViewController

Question

I have a project in Swift in which I added a ViewController written in Objective C that ranges all beacons that it finds in his range (didn't find a swift code for this - this is why I'm using Obj C). I connected the two ViewControllers and all is good, the beacons are displayed on the screen of the Objective C ViewController. The problem is that I need to access, from the Objective C ViewController, a dictionary ("beaconsDict"), that is created in there, so I can pass all beacons RSSIs to a BLE gateway afterwards. The problem is that I don't know how to read/access from the Swift ViewController the Dictionary from the Obj C ViewController so I can create a list of RSSIs which, afterwards, I will pass to the BLE Gateway.

(the bridging is done and as I mentioned the Obj C ViewController is visible in my application, at a push of a button, and works as expected)

Obj C ViewController m file:

#import "AIBMainTableViewController.h"
#import "AIBBeaconRegionAny.h"
#import "AIBUtils.h"
#import "AIBDetailViewController.h"

#define  kCellIdentifier @"cellBeaconIdentifier"

@import CoreLocation;

@interface AIBMainTableViewController ()<CLLocationManagerDelegate>

@property(nonatomic, strong) NSDictionary*      beaconsDict;
@property(nonatomic, strong) CLLocationManager* locationManager;
@property(nonatomic, strong) NSArray*           listUUID;
@property(nonatomic)         BOOL               sortByMajorMinor;
@property(nonatomic, retain) CLBeacon*          selectedBeacon;

@end

@implementation AIBMainTableViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.clearsSelectionOnViewWillAppear = NO;
    
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    
    self.listUUID=[[NSArray alloc] init];
    self.beaconsDict=[[NSMutableDictionary alloc] init];
    self.sortByMajorMinor=NO;
    
    AIBBeaconRegionAny *beaconRegionAny = [[AIBBeaconRegionAny alloc] initWithIdentifier:@"Any"];
    [self.locationManager requestWhenInUseAuthorization];
    [self.locationManager startRangingBeaconsInRegion:beaconRegionAny];
        
    self.navigationItem.rightBarButtonItem=[[UIBarButtonItem alloc] initWithTitle:@"Order by major/minor" style:UIBarButtonItemStylePlain target:self action:@selector(changeOrdenation)];
}

- (void) changeOrdenation{
    _sortByMajorMinor=!_sortByMajorMinor;
    if (_sortByMajorMinor){
        self.navigationItem.rightBarButtonItem.title=@"Order by distance";
    } else {
        self.navigationItem.rightBarButtonItem.title=@"Order by major/minor";
    }
}

- (void)locationManager:(CLLocationManager *)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status
{
    NSLog(@"locationManagerDidChangeAuthorizationStatus: %d", status);
    
    [UIAlertController alertControllerWithTitle:@"Authoritzation Status changed"
                                        message:[[NSString alloc] initWithFormat:@"Location Manager did change authorization status to: %d", status]
                                 preferredStyle:UIAlertControllerStyleAlert];
    
}

- (void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray *)beacons inRegion:(CLBeaconRegion *)region
{
    NSLog(@"locationManager:%@ didRangeBeacons:%@ inRegion:%@",manager, beacons, region);

    NSMutableArray* listUuid=[[NSMutableArray alloc] init];
    NSMutableDictionary* beaconsDict=[[NSMutableDictionary alloc] init];
    for (CLBeacon* beacon in beacons) {
        NSLog(@"rssi is : %ld", beacon.rssi);
        NSString* uuid=[beacon.proximityUUID UUIDString];
        NSMutableArray* list=[beaconsDict objectForKey:uuid];
        if (list==nil){
            list=[[NSMutableArray alloc] init];
            [listUuid addObject:uuid];
            [beaconsDict setObject:list forKey:uuid];
        }
        [list addObject:beacon];
    }

    [listUuid sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        NSString* string1=obj1;
        NSString* string2=obj2;
        return [string1 compare:string2];
    }];
    if (_sortByMajorMinor){
        for (NSString* uuid in listUuid){
            NSMutableArray* list=[beaconsDict objectForKey:uuid];
            [list sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
                CLBeacon* b1=obj1;
                CLBeacon* b2=obj2;
                NSComparisonResult r=[b1.major compare:b2.major];
                if (r==NSOrderedSame){
                    r=[b1.minor compare:b2.minor];
                }
                return r;
            }];
        }
    }
    _listUUID=listUuid;
    _beaconsDict=beaconsDict;
    
    [self.tableView reloadData];
}

- (void)locationManager:(CLLocationManager *)manager rangingBeaconsDidFailForRegion:(CLBeaconRegion *)region withError:(NSError *)error
{
     NSLog(@"locationManager:%@ rangingBeaconsDidFailForRegion:%@ withError:%@", manager, region, error);
    
    [UIAlertController alertControllerWithTitle:@"Ranging Beacons fail"
                                        message:[[NSString alloc] initWithFormat:@"Ranging beacons fail with error: %@", error]
                                 preferredStyle:UIAlertControllerStyleAlert];
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return [_listUUID count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    NSString* key=[_listUUID objectAtIndex:section];
    return [[_beaconsDict objectForKey:key] count];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{
    return [_listUUID objectAtIndex:section];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kCellIdentifier forIndexPath:indexPath];
    
    NSString* key=[_listUUID objectAtIndex:[indexPath indexAtPosition:0]];
    CLBeacon* beacon=[[_beaconsDict objectForKey:key] objectAtIndex:[indexPath indexAtPosition:1]];
    cell.textLabel.text=[[NSString alloc] initWithFormat:@"RSSI:%ld", (long)beacon.rssi];
    
    cell.detailTextLabel.text=[[NSString alloc] initWithFormat:@"Distance: %.2fm\tProximity: %@", beacon.accuracy, [AIBUtils stringForProximityValue:beacon.proximity]];
    
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    NSString* key=[_listUUID objectAtIndex:[indexPath indexAtPosition:0]];
    _selectedBeacon=[[_beaconsDict objectForKey:key] objectAtIndex:[indexPath indexAtPosition:1]];

    AIBDetailViewController* detail=[self.storyboard instantiateViewControllerWithIdentifier:@"detail"];
    detail.beacon=_selectedBeacon;
    [self.navigationController pushViewController:detail animated:YES];
}

@end

Obj C ViewController h file:

#import <UIKit/UIKit.h>

@interface AIBMainTableViewController : UITableViewController


@end

Answer 1

Approach 1:

Declare NSDictionary *dictionaryBeacons; in your .h file. Initialization and value assignment will happen in .m

Then in .swift file you can declare one property like var dictBeacons: [String:Any]?

Now in .m file you can create object of swift view controller and pass dict as parameter like

vcObject.dictBeacons = dictionaryBeacons; and then PUSH it using navigation controller.

Approach 2:

If you don't want PUSH controller and use it in random .swift class then Declare @property(nonatomic, strong) NSDictionary *dictionaryBeacons; in your .h file and use it any .swift class by creating object of VC like vcObject.dictionaryBeacons