[!] Unable to find a specification for TokenCoreDep depended upon by TokenCore

[likuiliang]

bogon:Example likuiliang-Answer$ pod install
/usr/local/lib/ruby/gems/2.4.0/gems/cocoapods-1.5.3/lib/cocoapods/executable.rb:89: warning: Insecure world writable dir /Users/answer/Documents/flutter/bin in PATH, mode 040777
Analyzing dependencies
Pre-downloading: TokenCore from https://github.com/consenlabs/token-core-ios.git
[!] Unable to find a specification for TokenCoreDep depended upon by TokenCore

[likuiliang]

如此解决：pod 'TokenCore', :git=> 'https://github.com/consenlabs/token-core-ios.git',:commit=>'03817d489a42d882ccffae45468e4199f807dc06'

[SuperDarrenChain]

Analyzing dependencies
Pre-downloading: TokenCore from https://github.com/consenlabs/token-core-ios.git, commit 03817d489a42d882ccffae45468e4199f807dc06
[!] CocoaPods could not find compatible versions for pod "CryptoSwift":
In snapshot (Podfile.lock):
CryptoSwift (= 1.0.0, >= 0.10.0)

In Podfile:
CryptoSwift (>= 0.10.0)

TokenCore (from `https://github.com/consenlabs/token-core-ios.git`, commit `03817d489a42d882ccffae45468e4199f807dc06`) was resolved to 0.1, which depends on
  CryptoSwift (= 0.9.0)

Specs satisfying the CryptoSwift (>= 0.10.0), CryptoSwift (= 1.0.0, >= 0.10.0), CryptoSwift (= 0.9.0) dependency were found, but they required a higher minimum deployment target.

我这边用pod 'TokenCore', :git=> 'https://github.com/consenlabs/token-core-ios.git',:commit=>'03817d489a42d882ccffae45468e4199f807dc06' 报错这个是
什么原因