出现场景
使用某个三方库时，跑在IOS上报错。
最近在用Flutter做蓝牙相关的App，需要用到蓝牙库，就找到了flutter_reactive_ble这个库。最后运行在ios上时，直接报错。提示CocoaPods could not find compatible versions for pod "flutter_reactive_ble"。
详细报错信息如下
CocoaPods' output: ↳ Preparing Analyzing dependencies Inspecting targets to integrate Using `ARCHS` setting to build architectures of target `Pods-Runner`: (``) Fetching external sources -> Fetching podspec for `Flutter` from `Flutter` -> Fetching podspec for `device_info_plus` from `.symlinks/plugins/device_info_plus/ios` -> Fetching podspec for `flutter_reactive_ble` from `.symlinks/plugins/flutter_reactive_ble/ios` -> Fetching podspec for `location_permissions` from `.symlinks/plugins/location_permissions/ios` -> Fetching podspec for `path_provider` from `.symlinks/plugins/path_provider/ios` Resolving dependencies of `Podfile` CDN: trunk Relative path: CocoaPods-version.yml exists! Returning local because checking is only perfomed in repo update [!] CocoaPods could not find compatible versions for pod "flutter_reactive_ble": In Podfile: flutter_reactive_ble (from `.symlinks/plugins/flutter_reactive_ble/ios`) Specs satisfying the `flutter_reactive_ble (from `.symlinks/plugins/flutter_reactive_ble/ios`)` dependency were found, but they required a higher minimum deployment target. /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:328:in `raise_error_unless_state' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:310:in `block in unwind_for_conflict' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:308:in `tap' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:308:in `unwind_for_conflict' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:684:in `attempt_to_activate' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:254:in `process_topmost_state' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:182:in `resolve' /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolver.rb:43:in `resolve' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/resolver.rb:94:in `resolve' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer/analyzer.rb:1074:in `block in resolve_dependencies' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/user_interface.rb:64:in `section' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer/analyzer.rb:1072:in `resolve_dependencies' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer/analyzer.rb:124:in `analyze' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer.rb:414:in `analyze' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer.rb:239:in `block in resolve_dependencies' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/user_interface.rb:64:in `section' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer.rb:238:in `resolve_dependencies' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/installer.rb:160:in `install!' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/command/install.rb:52:in `run' /Library/Ruby/Gems/2.6.0/gems/claide-1.0.3/lib/claide/command.rb:334:in `run' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/lib/cocoapods/command.rb:52:in `run' /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.10.1/bin/pod:55:in `<top (required)>' /usr/local/bin/pod:23:in `load' /usr/local/bin/pod:23:in `<main>' Error output from CocoaPods: ↳ [!] Automatically assigning platform `iOS` with version `9.0` on target `Runner` because no platform was specified. Please specify a platform for this target in your Podfile. See `https://guides.cocoapods.org/syntax/podfile.html#platform`. Error running pod install Error launching application on iPhone 12 Pro Max.
原因
打开ios项目中的pods/Local Podspecs目录，这里面存储的是所有pubspec.yaml中使用的了的三方库配置信息，因为我这个项目是因为flutter_reactive_ble这个库而引起的问题，所以打开flutter_reactive_ble.podspec.json，在最下面可以看到以下内容
"platforms": { "ios": "11.0", "osx": "10.13" },
看到这里就能知道什么问题啦了。
这个库要求ios的最低版本在11.0。而我的项目还没有指定最低版本，默认就使用了9.0来编译。所以会提示不兼容。
解决方案
打开ios/Podfile文件，将第二行的内容去掉注释。将后面的版本改为上面库里面对应的版本即可。
# Uncomment this line to define a global platform for your project # platform :ios, '9.0' platform :ios, '11.0'
因为flutter_reactive_ble最低要求11.0，所以在这里改成11.0即可。最后重新运行，等待pod install、xcode build之后，就能成功运行起来了。
