objective-c - React native bridge 在 swift 模块中有时为 nil

Question

我创建了一个 swift 模块，当从 swift 调用连接方法时，它开始监听 GCDAsyncUdpSocket

@objc(MyModule)
class MyModule: NSObject, GCDAsyncUdpSocketDelegate {
  var bridge: RCTBridge!
  var socket: GCDAsyncUdpSocket!

  func methodQueue() -> dispatch_queue_t {
    return dispatch_queue_create("com.mycompany.greatapp", DISPATCH_QUEUE_SERIAL)
  }

  @objc func connect(resolver resolve: RCTPromiseResolveBlock, rejecter reject: RCTPromiseRejectBlock) {
    socket = GCDAsyncUdpSocket(delegate: self, delegateQueue: methodQueue())

    //...start listening, etc
  }

  @objc func udpSocket(sock: GCDAsyncUdpSocket!, didReceiveData data: NSData!, fromAddress address: NSData!, withFilterContext filterContext: AnyObject!) {
    bridge.eventDispatcher().sendAppEventWithName("got_msg", body: nil)
  }
}

我还创建了一个私有(private)实现

#import <Foundation/Foundation.h>
#import "RCTBridgeModule.h"

@interface RCT_EXTERN_MODULE(MyModule, NSObject)

RCT_EXTERN_METHOD(connect resolver:(RCTPromiseResolveBlock *)resolve
                  rejecter:(RCTPromiseRejectBlock *)reject)

@end

但是有时 bridge.eventDispatcher() 解包为 nil 并且无法广播事件。如有任何想法，我们将不胜感激。

Answer 1

这个 Github 问题让我找到了解决方案:https://github.com/facebook/react-native/issues/3454 .原来这只发生在重新加载时。需要实现 RCTInvalidating，然后清除 invalidate 中的任何悬空引用。这允许 ARC 正确清理您的 native 模块并重新实例化 RCTBridge

@objc(MyModule)
class MyModule: NSObject, GCDAsyncUdpSocketDelegate, RCTInvalidating {
  var bridge: RCTBridge!
  var socket: GCDAsyncUdpSocket!

  func invalidate() {
    self.socket = nil
  }

  func methodQueue() -> dispatch_queue_t {
    return dispatch_queue_create("com.mycompany.greatapp", DISPATCH_QUEUE_SERIAL)
  }

  @objc func connect(resolver resolve: RCTPromiseResolveBlock, rejecter reject: RCTPromiseRejectBlock) {
    socket = GCDAsyncUdpSocket(delegate: self, delegateQueue: methodQueue())

    //...start listening, etc
  }

  @objc func udpSocket(sock: GCDAsyncUdpSocket!, didReceiveData data: NSData!, fromAddress address: NSData!, withFilterContext filterContext: AnyObject!) {
    bridge.eventDispatcher().sendAppEventWithName("got_msg", body: nil)
  }
}