I used CocoaPods with my app I noticed I can't open pod file and the file turn to exec file like the image down, I need to edit it to add new libraries.
Open the Podfile with TextEdit use terminal
$ cd "your_project_location"
$ open -a TextEdit Podfile
I think you will try these steps :
1- $ cd Your file location
2- $ open -a Xcode Podfile
Open file from Terminal
vim Podfile
1.open podfile from terminal
$ cd "your_project_location that contain podfile"
$ nano Podfile
2.You can also open podfile using xcode
Right click to podfile and choose openwith xcode.
Drag and drop it to TextEdit or open project in XCode and edit there.
来源：https://stackoverflow.com/questions/38307085/how-can-i-open-podfile-for-editing