同有问题，好像是 WDA 已经支持，但是 Appium 还不支持

我的解决方案（仅供参考）：

appium-xcuitest-driver@2.4.0中的/lib/webdriveragent.js的waitForStart函数中，需要获得 WDA 的启动时间与系统时间做对比，导致reachedEnd一直是false，测试进程卡住，等待 WDA 启动，具体的代码如下：

async waitForStart (startTime) {
    // we have to wait for the sim to start before we can tail the log file
    if (!this.realDevice) {
      await systemLogExists(this.device);
    }

    let agentUrl;
    let lineCount = 0;
    let reachedEnd = !this.realDevice; // simulator does not need to wait, since we are tailing
    let showWaitingMessage = true; // turn off logging once we have hit the end

    let startDetector = (stdout) => {
      // on a real device there may already be system logs that need to be
      // passed before we get to the real startup logs, otherwise
      // we expect two lines, one after another
      //     Jul 20 13:03:57 iamPhone XCTRunner[296] <Warning>: Built at Jul 20 2016 13:03:50
      //     Jul 20 13:03:57 iamPhone XCTRunner[296] <Warning>: ServerURLHere->http://10.35.4.122:8100<-ServerURLHere
      if (!reachedEnd) {
        let dateMatch = REAL_DEVICE_BUILD_LOG_STARTTIME_REGEX.exec(stdout);
        if (dateMatch) {
          let buildTime = new Date(dateMatch[1]);
          if (buildTime.isAfter(startTime)) {
            reachedEnd = true;
          }
        }
      }

      if (reachedEnd) {
        let match = AGENT_STARTED_REGEX.exec(stdout);
        if (match) {
          agentUrl = match[1];
          log.info(`Detected that WebDriverAgent is running at url '${agentUrl}'`);
          if (!agentUrl) {
            log.errorAndThrow(new Error('No url detected from WebDriverAgent'));
          }
          showWaitingMessage = false;
          return true;
        }
      }

      // periodically log, so it does not look like everything died
      lineCount++;
      let threshold = this.realDevice ? 5000 : 200;
      if (showWaitingMessage && lineCount % threshold === 0) {
        log.debug('Waiting for WebDriverAgent server to finish loading...');
      }

      return false;
    };

    log.info('Waiting for WebDriverAgent to start on device');
    await this.deviceLogs.start(startDetector);
    log.info(`WebDriverAgent started at url '${agentUrl}'`);

    return agentUrl;
  }

解决方法：

当前的解决方案是修改对应代码：

if (!reachedEnd) {
        // let dateMatch = REAL_DEVICE_BUILD_LOG_STARTTIME_REGEX.exec(stdout);
        // if (dateMatch) {
        //   let buildTime = new Date(dateMatch[1]);
        //   if (buildTime.isAfter(startTime)) {
        //     reachedEnd = true;
        //   }
        // }
        reachedEnd = true;
        log.info("ReachedEnd is set true!")
      } 

PS：
appium-xcuitest-driver@2.4.3与 2.4.0 的源码不一样，但是原理差不多。
另外，需要修改 build 中编译后的文件或者修改后编译一下。