Reactnative Xcode 设备不可用，未找到运行时配置文件

在以下环境中:

Xcode 8.3.2
react-native-cli 2.0.1
react-native: 0.44.0
macOS Sierra 10.12.5

刚刚更新了Xcode和macOS以运行React Native并像几天前一样继续练习...但每次我try run 时:

react-native run-ios

我得到了一个错误:

Scanning 555 folders for symlinks in /Users/juangarcia/projects/react-tests/CountDown/node_modules (6ms)
Found Xcode project CountDown.xcodeproj

Could not find iPhone 6 simulator

我试图查看可用设备的列表，我得到:

~/projects/react-tests/CountDownSample » xcrun simctl list devices
== Devices ==
-- iOS 10.3 --
-- tvOS 10.2 --
    Apple TV 1080p (323FA90C-0366-4B5B-AEEE-D0477C61762A) (Shutdown)
-- watchOS 3.2 --
    Apple Watch - 38mm (F42C0C0D-325B-41DD-948D-E44B0A08B951) (Shutdown)
    Apple Watch - 42mm (75D8BAF1-27CB-47EE-9EE3-D400B962F8BC) (Shutdown)
    Apple Watch Series 2 - 38mm (64D01BD4-5C37-4885-A73A-52479D9CCF4F) (Shutdown)
    Apple Watch Series 2 - 42mm (8471C9FD-BCF3-4DDC-B386-F17E128C5EB1) (Shutdown)
-- Unavailable: com.apple.CoreSimulator.SimRuntime.iOS-9-3 --
    iPhone 4s (1FF2D0D3-F136-43A7-8148-7B1849A7B1E3) (Shutdown) (unavailable, runtime profile not found)
    iPhone 5 (859D4D90-F1B5-4DE8-B976-6984F85CAFE3) (Shutdown) (unavailable, runtime profile not found)
    iPhone 5s (5B2AD8CD-9B3F-413C-BF16-FA96F807BB2B) (Shutdown) (unavailable, runtime profile not found)
    iPhone 6 (2573D214-4371-47A8-BFF6-3341862954E0) (Shutdown) (unavailable, runtime profile not found)
    iPhone 6 Plus (8916CD9B-4D8B-463F-8583-75A2CE4F61FD) (Shutdown) (unavailable, runtime profile not found)
    iPhone 6s (41093980-7912-4F98-9D06-981A533FAAFE) (Shutdown) (unavailable, runtime profile not found)
    iPhone 6s Plus (6A85D2AE-D867-4341-979C-FEE8308DE93E) (Shutdown) (unavailable, runtime profile not found)
    iPad 2 (BFBB5477-B6D9-48C3-B529-516D2D9105A7) (Shutdown) (unavailable, runtime profile not found)
    iPad Retina (C49B5920-F4FF-4D7F-AA74-7AE2367FF09D) (Shutdown) (unavailable, runtime profile not found)
    iPad Air (4101FC8E-D8B9-4496-AD2B-1484661C15DE) (Shutdown) (unavailable, runtime profile not found)
    iPad Air 2 (9952B05C-829F-428F-AC76-EB1F8FB55D72) (Shutdown) (unavailable, runtime profile not found)
    iPad Pro (735082E2-4470-4D9A-BAA1-BEDA8426B725) (Shutdown) (unavailable, runtime profile not found)
-- Unavailable: com.apple.CoreSimulator.SimRuntime.tvOS-9-2 --
    Apple TV 1080p (AD48DE24-6295-4EFC-9787-A9B5D8118503) (Shutdown) (unavailable, runtime profile not found)
-- Unavailable: com.apple.CoreSimulator.SimRuntime.watchOS-2-2 --
    Apple Watch - 38mm (C3F2A7C3-3967-4159-9B79-13CBA63E399E) (Shutdown) (unavailable, runtime profile not found)
    Apple Watch - 42mm (656005A9-7555-4872-A7FB-FB6BCB65139C) (Shutdown) (unavailable, runtime profile not found)

react默认使用Iphone 6，但不可用

how can I make it available again? and why did this happen?