How to use view created in swift inside an objective-c++ file?

[BraveEvidence]

I am trying to use react-native's new architecture and I have enabled fabric for the same. I am able to use a view created in objective-c++ inside my typescript code. But I want to use a view created in swift with UIKit in my objective-c++ file

The documentation on react-native's website is still for the old architecture of using bridge so it does not directly apply in my case. There are pretty significant changes in the new architecture.

Below is the working code for objective-c++ file

 #import <Foundation/Foundation.h>
    #import "RNThubView.h"
    
    #import <react/renderer/components/RNThubViewSpec/ComponentDescriptors.h>
    #import <react/renderer/components/RNThubViewSpec/EventEmitters.h>
    #import <react/renderer/components/RNThubViewSpec/Props.h>
    #import <react/renderer/components/RNThubViewSpec/RCTComponentViewHelpers.h>
    
    #import "RCTFabric/React-RCTFabric-umbrella.h"
    
    
    
    using namespace facebook::react;
    
    @interface RNThubView () <RCTThubViewViewProtocol>
    
    @end
    
    @implementation RNThubView {
      UIView *_view;
      UILabel *_label;
    }
    
    + (ComponentDescriptorProvider)componentDescriptorProvider
    {
      return concreteComponentDescriptorProvider<ThubViewComponentDescriptor>();
    }
    
    - (instancetype)initWithFrame:(CGRect)frame
    {
      if (self = [super initWithFrame:frame]) {
        static const auto defaultProps = std::make_shared<const ThubViewProps>();
        
        _props = defaultProps;
        
        
        _rnThubView = [[RNThubView alloc] init];
        _view = [[UIView alloc] init];
        
        _label = [[UILabel alloc] init];
        _label.text = @"Initial value";
        [_view addSubview:_label];
        
        _label.translatesAutoresizingMaskIntoConstraints = false;
        [NSLayoutConstraint activateConstraints:@[
          [_label.leadingAnchor constraintEqualToAnchor:_view.leadingAnchor],
          [_label.topAnchor constraintEqualToAnchor:_view.topAnchor],
          [_label.trailingAnchor constraintEqualToAnchor:_view.trailingAnchor],
          [_label.bottomAnchor constraintEqualToAnchor:_view.bottomAnchor],
        ]];
        _label.textAlignment = NSTextAlignmentCenter;
        
        self.contentView = _view;
    
        
      }
      
      return self;
    }
    
    - (void)updateProps:(Props::Shared const &)props oldProps:(Props::Shared const &)oldProps
    {
      const auto &oldViewProps = *std::static_pointer_cast<ThubViewProps const>(_props);
      const auto &newViewProps = *std::static_pointer_cast<ThubViewProps const>(props);
      
      if (oldViewProps.color != newViewProps.color) {
        //    NSString * colorToConvert = [[NSString alloc] initWithUTF8String: newViewProps.color.c_str()];
        //    [_view setBackgroundColor:[self hexStringToColor:colorToConvert]];
        //    _view.backgroundColor = [UIColor redColor];
      }
      
      [super updateProps:props oldProps:oldProps];
    }
    
    Class<RCTComponentViewProtocol> ThubViewCls(void)
    {
      return RNThubView.class;
    }
    
    - hexStringToColor:(NSString *)stringToConvert
    {
      NSString *noHashString = [stringToConvert stringByReplacingOccurrencesOfString:@"#" withString:@""];
      NSScanner *stringScanner = [NSScanner scannerWithString:noHashString];
      
      unsigned hex;
      if (![stringScanner scanHexInt:&hex]) return nil;
      int r = (hex >> 16) & 0xFF;
      int g = (hex >> 8) & 0xFF;
      int b = (hex) & 0xFF;
      
      return [UIColor colorWithRed:r / 255.0f green:g / 255.0f blue:b / 255.0f alpha:1.0f];
    }
    
    @end

Now to use a view which is created in swift inside my objective-c++ file, I use the following approach

Created a swift file called RNThubView. Following is the code for the same

@objcMembers class RNThubView: UIView {
  let btnLogin:UIButton = {
      let btn = UIButton(type:.system)
      btn.backgroundColor = .blue
      btn.setTitle("Login", for: .normal)
      btn.tintColor = .white
      btn.layer.cornerRadius = 5
      btn.clipsToBounds = true
      btn.translatesAutoresizingMaskIntoConstraints = false
      return btn
  }()
  
  
  required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
  }
  
  override init(frame: CGRect) {
    super.init(frame: frame)
    self.addSubview(btnLogin)
    addConstraintsToButtonLogin()
  }
  
  func addConstraintsToButtonLogin(){
    btnLogin.leftAnchor.constraint(equalTo: self.leftAnchor).isActive = true
      btnLogin.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
      btnLogin.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
      btnLogin.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
  }
  
  
}

And I updated my objective-c++ file code to the following

- (instancetype)initWithFrame:(CGRect)frame
{
  if (self = [super initWithFrame:frame]) {
    static const auto defaultProps = std::make_shared<const ThubViewProps>();
    
    _props = defaultProps;
     
    
    _rnThubView = [[RNThubView alloc] init];
    self.contentView = _rnThubView
   .....

Rest of the code remains mostly the same in objective-c++ file.

Now when I run via cli, the app crashes with no logs on cli. When I run via Xcode, I get following logs with a white screen on the simulator

flipper: FlipperClient::addPlugin Inspector
flipper: FlipperClient::addPlugin Preferences
flipper: FlipperClient::addPlugin React
flipper: FlipperClient::addPlugin Network
2022-07-04 19:16:34.262238+0530 FabricSwift[51914:596543] [connection] nw_socket_handle_socket_event [C1.1:1] Socket SO_ERROR [61: Connection refused]
2022-07-04 19:16:34.290263+0530 FabricSwift[51914:596543] [connection] nw_socket_handle_socket_event [C1.2:1] Socket SO_ERROR [61: Connection refused]
2022-07-04 19:16:34.293022+0530 FabricSwift[51914:596537] [connection] nw_connection_get_connected_socket [C1] Client called nw_connection_get_connected_socket on unconnected nw_connection
2022-07-04 19:16:34.296327+0530 FabricSwift[51914:596537] TCP Conn 0x600001130370 Failed : error 0:61 [61]
2022-07-04 19:16:36.557475+0530 FabricSwift[51914:596543] [connection] nw_socket_handle_socket_event [C5.1:1] Socket SO_ERROR [61: Connection refused]
2022-07-04 19:16:36.558768+0530 FabricSwift[51914:596543] [connection] nw_socket_handle_socket_event [C5.2:1] Socket SO_ERROR [61: Connection refused]
2022-07-04 19:16:36.559075+0530 FabricSwift[51914:596538] [connection] nw_connection_get_connected_socket [C5] Client called nw_connection_get_connected_socket on unconnected nw_connection
2022-07-04 19:16:36.559146+0530 FabricSwift[51914:596538] TCP Conn 0x600001104840 Failed : error 0:61 [61]
2022-07-04 19:16:36.728528+0530 FabricSwift[51914:596578] [javascript] Running "FabricSwift" with {"fabric":true,"initialProps":{"concurrentRoot":true},"rootTag":1}
2022-07-04 19:16:37.065773+0530 FabricSwift[51914:596539] [connection] nw_socket_handle_socket_event [C9.1:1] Socket SO_ERROR [61: Connection refused]
2022-07-04 19:16:37.066881+0530 FabricSwift[51914:596539] [connection] nw_socket_handle_socket_event [C9.2:1] Socket SO_ERROR [61: Connection refused]
2022-07-04 19:16:37.067294+0530 FabricSwift[51914:596539] [connection] nw_connection_get_connected_socket [C9] Client called nw_connection_get_connected_socket on unconnected nw_connection
2022-07-04 19:16:37.067425+0530 FabricSwift[51914:596539] TCP Conn 0x6000011370d0 Failed : error 0:61 [61]
assertion failed [thread_context != nullptr]: got an exception for an unknown thread
(ExceptionServer.cpp:809 handle_exception)
Message from debugger: Xcode has killed the LLDB RPC server to allow the debugger to detach from your process. You may need to manually terminate your process.

Full source is here https://github.com/PritishSawant/ReactNativeFabricSwiftTry

Also how to pass props from objective-c++ to swift. In my example it is a color prop which once set from react-native's side should use the value in my swift file.

[cortinico]

Disclaimer: I'm not a Swift expert.

I believe what you're trying to achieve is not possible. In order to use Swift, you'll have to enable use_frameworks which is currently not supported in the New Architecture. We're actively looking into it, but it's not possible to use Swift with the New Architecture as of today.

[BraveEvidence]

Hey @cortinico

Check this repo

I have used swift with TurboModules and it works. Just need help with Fabric

[BraveEvidence]

@cortinico Also check this