ios: Start using CocoaPods again.

There was an attempt to use CocoaPods in aded466, 2017-03-19.

That was removed in 4096e71, 2017-07-18.

Some cleanup was done in 861744b, 2020-02-05.

To paraphrase Greg on zulip#3983:

CocoaPods is a tool for managing iOS libraries. Many people use it
in their React Native apps, but there some tricky bits that have
impeded universal adoption.

RN v0.60 signals a full embrace of the use of CocoaPods by making it
work more smoothly with RN. CocoaPods becomes required in v0.61.

So, use CocoaPods, writing a Podfile based on the example Podfile
given for react-native v0.59, at
https://github.com/facebook/react-native-website/blob/ded79d2cf4456d8b1a4f67c2cdc1391789e70617/docs/integration-with-existing-apps.md.
(That doc isn't live on the react-native docs website because of
facebook/react-native-website#1603.)

Originally, we were going to start using CocoaPods as part of the RN
v0.60 upgrade, but we have a fresh reason to want to use CocoaPods,
with its own deadline: zulip#3964, Apple auth. Someone has made a handy
Expo package to handle Apple auth, but we can't use Expo packages
without either fully committing to using the Expo SDK (a dramatic
step) or using a package called react-native-unimodules, which lets
you select individual Expo packages. react-native-unimodules
requires the use of CocoaPods.

Fixes: zulip#3983

ios/Podfile

@@ -0,0 +1,36 @@
+# This was the iOS Deployment Target (project > ZulipMobile > Info in Xcode)
+# as of 2020-03.
+platform :ios, '10.3'
+
+require_relative '../node_modules/react-native-unimodules/cocoapods.rb'
+
+# See
+# https://github.com/facebook/react-native-website/blob/ded79d2cf4456d8b1a4f67c2cdc1391789e70617/docs/integration-with-existing-apps.md#configuring-cocoapods-dependencies
+# for the choice of pods here.
+target 'ZulipMobile' do
+  pod 'React', :path => '../node_modules/react-native', :subspecs => [
+    'Core',
+    'CxxBridge', # Include this for RN >= 0.47
+    'DevSupport', # Include this to enable In-App Devmenu if RN >= 0.43
+    'RCTText',
+    'RCTNetwork',
+    'RCTWebSocket', # Needed for debugging
+    'RCTAnimation', # Needed for FlatList and animations running on native UI thread
+    # Add any other subspecs you want to use in your project
+  ]
+  # Explicitly include Yoga if you are using RN >= 0.42.0
+  pod 'yoga', :path => '../node_modules/react-native/ReactCommon/yoga'
+
+  # Third party deps podspec link
+  pod 'DoubleConversion', :podspec => '../node_modules/react-native/third-party-podspecs/DoubleConversion.podspec'
+  pod 'glog', :podspec => '../node_modules/react-native/third-party-podspecs/glog.podspec'
+  pod 'Folly', :podspec => '../node_modules/react-native/third-party-podspecs/Folly.podspec'
+
+  use_unimodules!
+
+  target 'ZulipMobileTests' do
+    inherit! :search_paths
+    # Pods for testing
+  end
+
+end

ios/Podfile.lock

@@ -0,0 +1,197 @@
+PODS:
+  - boost-for-react-native (1.63.0)
+  - DoubleConversion (1.1.6)
+  - EXAppLoaderProvider (7.0.0)
+  - EXConstants (7.0.1):
+    - UMConstantsInterface
+    - UMCore
+  - EXFileSystem (7.0.0):
+    - UMCore
+    - UMFileSystemInterface
+  - EXPermissions (7.0.0):
+    - UMCore
+    - UMPermissionsInterface
+  - Folly (2018.10.22.00):
+    - boost-for-react-native
+    - DoubleConversion
+    - glog
+  - glog (0.3.5)
+  - React (0.59.10):
+    - React/Core (= 0.59.10)
+  - React/Core (0.59.10):
+    - yoga (= 0.59.10.React)
+  - React/CxxBridge (0.59.10):
+    - Folly (= 2018.10.22.00)
+    - React/Core
+    - React/cxxreact
+    - React/jsiexecutor
+  - React/cxxreact (0.59.10):
+    - boost-for-react-native (= 1.63.0)
+    - DoubleConversion
+    - Folly (= 2018.10.22.00)
+    - glog
+    - React/jsinspector
+  - React/DevSupport (0.59.10):
+    - React/Core
+    - React/RCTWebSocket
+  - React/fishhook (0.59.10)
+  - React/jsi (0.59.10):
+    - DoubleConversion
+    - Folly (= 2018.10.22.00)
+    - glog
+  - React/jsiexecutor (0.59.10):
+    - DoubleConversion
+    - Folly (= 2018.10.22.00)
+    - glog
+    - React/cxxreact
+    - React/jsi
+  - React/jsinspector (0.59.10)
+  - React/RCTAnimation (0.59.10):
+    - React/Core
+  - React/RCTBlob (0.59.10):
+    - React/Core
+  - React/RCTNetwork (0.59.10):
+    - React/Core
+  - React/RCTText (0.59.10):
+    - React/Core
+  - React/RCTWebSocket (0.59.10):
+    - React/Core
+    - React/fishhook
+    - React/RCTBlob
+  - UMBarCodeScannerInterface (4.0.0)
+  - UMCameraInterface (4.0.0)
+  - UMConstantsInterface (4.0.0)
+  - UMCore (4.0.0)
+  - UMFaceDetectorInterface (4.0.0)
+  - UMFileSystemInterface (4.0.0)
+  - UMFontInterface (4.0.0)
+  - UMImageLoaderInterface (4.0.0)
+  - UMPermissionsInterface (4.0.0)
+  - UMReactNativeAdapter (4.0.0):
+    - React
+    - UMCore
+    - UMFontInterface
+  - UMSensorsInterface (4.0.0)
+  - UMTaskManagerInterface (4.0.0)
+  - yoga (0.59.10.React)
+
+DEPENDENCIES:
+  - DoubleConversion (from `../node_modules/react-native/third-party-podspecs/DoubleConversion.podspec`)
+  - EXAppLoaderProvider (from `../node_modules/expo-app-loader-provider/ios`)
+  - EXConstants (from `../node_modules/expo-constants/ios`)
+  - EXFileSystem (from `../node_modules/expo-file-system/ios`)
+  - EXPermissions (from `../node_modules/expo-permissions/ios`)
+  - Folly (from `../node_modules/react-native/third-party-podspecs/Folly.podspec`)
+  - glog (from `../node_modules/react-native/third-party-podspecs/glog.podspec`)
+  - React/Core (from `../node_modules/react-native`)
+  - React/CxxBridge (from `../node_modules/react-native`)
+  - React/DevSupport (from `../node_modules/react-native`)
+  - React/RCTAnimation (from `../node_modules/react-native`)
+  - React/RCTNetwork (from `../node_modules/react-native`)
+  - React/RCTText (from `../node_modules/react-native`)
+  - React/RCTWebSocket (from `../node_modules/react-native`)
+  - UMBarCodeScannerInterface (from `../node_modules/unimodules-barcode-scanner-interface/ios`)
+  - UMCameraInterface (from `../node_modules/unimodules-camera-interface/ios`)
+  - UMConstantsInterface (from `../node_modules/unimodules-constants-interface/ios`)
+  - "UMCore (from `../node_modules/@unimodules/core/ios`)"
+  - UMFaceDetectorInterface (from `../node_modules/unimodules-face-detector-interface/ios`)
+  - UMFileSystemInterface (from `../node_modules/unimodules-file-system-interface/ios`)
+  - UMFontInterface (from `../node_modules/unimodules-font-interface/ios`)
+  - UMImageLoaderInterface (from `../node_modules/unimodules-image-loader-interface/ios`)
+  - UMPermissionsInterface (from `../node_modules/unimodules-permissions-interface/ios`)
+  - "UMReactNativeAdapter (from `../node_modules/@unimodules/react-native-adapter/ios`)"
+  - UMSensorsInterface (from `../node_modules/unimodules-sensors-interface/ios`)
+  - UMTaskManagerInterface (from `../node_modules/unimodules-task-manager-interface/ios`)
+  - yoga (from `../node_modules/react-native/ReactCommon/yoga`)
+
+SPEC REPOS:
+  trunk:
+    - boost-for-react-native
+
+EXTERNAL SOURCES:
+  DoubleConversion:
+    :podspec: "../node_modules/react-native/third-party-podspecs/DoubleConversion.podspec"
+  EXAppLoaderProvider:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/expo-app-loader-provider/ios"
+  EXConstants:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/expo-constants/ios"
+  EXFileSystem:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/expo-file-system/ios"
+  EXPermissions:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/expo-permissions/ios"
+  Folly:
+    :podspec: "../node_modules/react-native/third-party-podspecs/Folly.podspec"
+  glog:
+    :podspec: "../node_modules/react-native/third-party-podspecs/glog.podspec"
+  React:
+    :path: "../node_modules/react-native"
+  UMBarCodeScannerInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-barcode-scanner-interface/ios"
+  UMCameraInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-camera-interface/ios"
+  UMConstantsInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-constants-interface/ios"
+  UMCore:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/@unimodules/core/ios"
+  UMFaceDetectorInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-face-detector-interface/ios"
+  UMFileSystemInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-file-system-interface/ios"
+  UMFontInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-font-interface/ios"
+  UMImageLoaderInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-image-loader-interface/ios"
+  UMPermissionsInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-permissions-interface/ios"
+  UMReactNativeAdapter:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/@unimodules/react-native-adapter/ios"
+  UMSensorsInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-sensors-interface/ios"
+  UMTaskManagerInterface:
+    :path: !ruby/object:Pathname
+    path: "../node_modules/unimodules-task-manager-interface/ios"
+  yoga:
+    :path: "../node_modules/react-native/ReactCommon/yoga"
+
+SPEC CHECKSUMS:
+  boost-for-react-native: 39c7adb57c4e60d6c5479dd8623128eb5b3f0f2c
+  DoubleConversion: bb338842f62ab1d708ceb63ec3d999f0f3d98ecd
+  EXAppLoaderProvider: 5d348813a9cf09b03bbe5b8b55437bc1bfbddbd1
+  EXConstants: 857aa7b1c84e2878f8402d712061860bca16a697
+  EXFileSystem: 7e53a2c30a2eb6987ba6d5158ab908f947523228
+  EXPermissions: df10ad83df2f6b647aec304619354f8ab48d5f63
+  Folly: de497beb10f102453a1afa9edbf8cf8a251890de
+  glog: aefd1eb5dda2ab95ba0938556f34b98e2da3a60d
+  React: 36d0768f9e93be2473b37e7fa64f92c1d5341eef
+  UMBarCodeScannerInterface: d5a6fdc98ed6241225b0a8432a7f4e2b397668bc
+  UMCameraInterface: 68870a3197fee85bd5afca5609ba4a5b7257d19d
+  UMConstantsInterface: d25b8e8887ca7aaf568c06caf08f4d40734ee4ef
+  UMCore: 402cee150324974974f5c32b5404d8af65e4cff5
+  UMFaceDetectorInterface: 7b4f1a92f0c726b58b086296048efe193b570678
+  UMFileSystemInterface: aadb9a67aa6470d7ebc06cf04dc54fee6781ac48
+  UMFontInterface: 2d3c128285086bbed3d2a650f1d698323ef3b25a
+  UMImageLoaderInterface: 2829a7571a12d2e754c73c55ffe7e327d8402c7d
+  UMPermissionsInterface: b6a6e96db0f4011a25aaca14e6022529dd3d6e4e
+  UMReactNativeAdapter: 93c2f520a1cdb6ef3058a7b6a95275a804e0923b
+  UMSensorsInterface: cf59dd7602764a2419e00167429be3e4be39c61d
+  UMTaskManagerInterface: 1e70fe58b872355f0ecb44fb81bb1a16484047f0
+  yoga: 684513b14b03201579ba3cee20218c9d1298b0cc
+
+PODFILE CHECKSUM: 3194227f6331ef767276e6757e018c5a0e320f60
+
+COCOAPODS: 1.9.1