求大神帮忙，第一次在 mac 上部署 appium 的环境，但是启动时，出现如下报错：

Launching Appium with command: '/Applications/Appium.app/Contents/Resources/node/bin/node' lib/server/main.js --command-timeout "7200" --pre-launch --debug-log-spacing --platform-version "8.4" --platform-name "iOS" --app "/Users/yspan/Library/Developer/Xcode/DerivedData/zhihuDaily_2.0-bpfufhrjjbcmelcsombxjoeaobjn/Build/Products/Debug-iphoneos/xxxx.app" --no-reset --show-ios-log --device-name "iPhone 5s" --native-instruments-lib

info: [debug] Starting Appium in pre-launch mode

info: Pre-launching app

info: *************************************
info: *************************************
info: *************************************
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info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: ****        NEW SESSION           ***
info: *************************************

info: *************************************
info: *************************************
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info: *************************************
info: *************************************
info: *************************************
info: [debug] Using local app from command line: /Users/yspan/Library/Developer/Xcode/DerivedData/zhihuDaily_2.0-bpfufhrjjbcmelcsombxjoeaobjn/Build/Products/Debug-iphoneos/xxxx.app

error: Could not pre-launch appium: Error: Bad app: /Users/yspan/Library/Developer/Xcode/DerivedData/zhihuDaily_2.0-bpfufhrjjbcmelcsombxjoeaobjn/Build/Products/Debug-iphoneos/xxxx.app. App paths need to be absolute, or relative to the appium server install dir, or a URL to compressed file, or a special app name. cause: Error: Error locating the app: ENOENT, stat '/Users/yspan/Library/Developer/Xcode/DerivedData/zhihuDaily_2.0-bpfufhrjjbcmelcsombxjoeaobjn/Build/Products/Debug-iphoneos/xxxx.app'

info: [debug] Got configuration error, not starting session
info: [debug] Cleaning up appium session

我的环境：
1、 OSX 10.11.1
2、 XCode Version 6.4
3、 Appium -1.4.13

相关步骤参考（https://testerhome.com/topics/3805）。