Actually, the main problem is with toolchain cmd I am getting an error when using that cmd .
I want an explanation regarding that 
$ toolchain
Traceback (most recent call last):
  File "/home/linuxbrew/.linuxbrew/bin/toolchain", line 5, in <module>
    from kivy_ios.toolchain import main
  File "/home/linuxbrew/.linuxbrew/opt/python@3.9/lib/python3.9/site-packages/kivy_ios/toolchain.py", line 245, in <module>
    class Arch64Simulator(Arch):
  File "/home/linuxbrew/.linuxbrew/opt/python@3.9/lib/python3.9/site-packages/kivy_ios/toolchain.py", line 250, in Arch64Simulator
    sysroot = sh.xcrun("--sdk", "iphonesimulator", "--show-sdk-path").strip()
  File "/home/linuxbrew/.linuxbrew/opt/python@3.9/lib/python3.9/site-packages/sh.py", line 3518, in __getattr__
    return self.__env[name]
  File "/home/linuxbrew/.linuxbrew/opt/python@3.9/lib/python3.9/site-packages/sh.py", line 3316, in __getitem__
    raise CommandNotFound(k)
sh.CommandNotFound: xcrun
This is the error that I am getting every time I use toolchain