1、打开终端cd到本地仓库，和.git同层（查看隐藏文件）
$ cd project
$ ls -a
2、创建.gitignore文件
$ vim .gitignore
3、键入 "i"，看到下面这个，进入编辑模式
-- INSERT --
4、把下面的这些复制进去
# Created by https://www.gitignore.io/api/objective-c
# Edit at https://www.gitignore.io/?templates=objective-c
### Objective-C ###
# Xcode
#
# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
## OS X
#
#DS_Store是mac系统中管理文件夹位置信息的文件
.DS_Store
*/.DS_Store
## vim or gvim每次写完代码的时候，项目中会多出很多*.swp文件
*.swp
## Build generated(编译时产生的文件)
build/
DerivedData/
## Various settings(其他设置)
*.pbxuser
!default.pbxuser
*.mode1v3
!default.mode1v3
*.mode2v3
!default.mode2v3
*.perspectivev3
!default.perspectivev3
xcuserdata/
## Other
*.moved-aside
*.xccheckout
*.xcscmblueprint
## Obj-C/Swift specific
*.hmap
*.ipa
*.dSYM.zip
*.dSYM
# CocoaPods(管理第三方的工具)
#
# We recommend against adding the Pods directory to your .gitignore. However
# you should judge for yourself, the pros and cons are mentioned at:
# https://guides.cocoapods.org/using/using-cocoapods.html#should-i-check-the-pods-directory-into-source-control
Pods/
# Carthage(类似于CocoaPods的管理第三方的工具)
#
# Add this line if you want to avoid checking in source code from Carthage dependencies.
# Carthage/Checkouts
Carthage/Build
# fastlane(自动打包工具集)
#
# It is recommended to not store the screenshots in the git repo. Instead, use fastlane to re-generate the
# screenshots whenever they are needed.
# For more information about the recommended setup visit:
# https://docs.fastlane.tools/best-practices/source-control/#source-control
fastlane/report.xml
fastlane/Preview.html
fastlane/screenshots/**/*.png
fastlane/test_output
# Code Injection(Xcode上的一个插件)
#
# After new code Injection tools there's a generated folder /iOSInjectionProject
# https://github.com/johnno1962/injectionforxcode
iOSInjectionProject/
### Objective-C Patch ###
# End of https://www.gitignore.io/api/objective-c
5、键入 "esc" ，退出编辑模式
6、键入 ":wq" ，保存并退出
到这里，就创建好了".gitignore"文件了！！
7、gitignore规则不生效的解决办法，先把本地缓存删除然后更新
git rm -r --cached .
git add .
git commit -m 'update .gitignore'
