xcodeenv: accept version & perform runtime checks

- xcodewrapper nix derivation has been updated to now accept a list of acceptable versions.
- allowHigher is now removed
- this matches closely to what we use for building react-native with nix at status-mobile repo
ref -> https://github.com/status-im/status-mobile/blob/develop/nix/pkgs/xcodeenv/compose-xcodewrapper.nix
- The key change done here is that now xcodewrapper checks Xcode versions at runtime instead of build time. This helps us to show warning messages when underlying environment does not have the Xcode version we want to support.

pkgs/development/mobile/xcodeenv/compose-xcodewrapper.nix

@@ -1,19 +1,41 @@
-{ stdenv, lib }:
-{ version ? "11.1"
-, allowHigher ? false
-, xcodeBaseDir ? "/Applications/Xcode.app" }:
+{ lib,
+  stdenv,
+  writeShellScriptBin }:
+{ versions ? [ ] , xcodeBaseDir ? "/Applications/Xcode.app" }:
 
 assert stdenv.isDarwin;
+let
+  xcodebuildPath = "${xcodeBaseDir}/Contents/Developer/usr/bin/xcodebuild";
 
+  xcodebuildWrapper = writeShellScriptBin "xcodebuild" ''
+    currentVer="$(${xcodebuildPath} -version | awk 'NR==1{print $2}')"
+    wrapperVers=(${lib.concatStringsSep " " versions})
+
+    for ver in "''${wrapperVers[@]}"; do
+      if [[ "$currentVer" == "$ver" ]]; then
+        # here exec replaces the shell without creating a new process
+        # https://www.gnu.org/software/bash/manual/bash.html#index-exec
+        exec "${xcodebuildPath}" "$@"
+      fi
+    done
+
+    echo "The installed Xcode version ($currentVer) does not match any of the allowed versions: ${lib.concatStringsSep ", " versions}"
+    echo "Please update your local Xcode installation to match one of the allowed versions"
+    exit 1
+  '';
+in
 stdenv.mkDerivation {
-  pname = "xcode-wrapper${lib.optionalString allowHigher "-plus"}";
-  inherit version;
+  name = "xcode-wrapper-impure";
   # Fails in sandbox. Use `--option sandbox relaxed` or `--option sandbox false`.
   __noChroot = true;
   buildCommand = ''
     mkdir -p $out/bin
     cd $out/bin
-    ln -s /usr/bin/xcode-select
+    ${if versions == [ ] then ''
+    ln -s "${xcodebuildPath}"
+    '' else ''
+    ln -s "${xcodebuildWrapper}/bin/xcode-select"
+    ''}
     ln -s /usr/bin/security
     ln -s /usr/bin/codesign
     ln -s /usr/bin/xcrun
@@ -22,23 +44,9 @@ stdenv.mkDerivation {
     ln -s /usr/bin/lipo
     ln -s /usr/bin/file
     ln -s /usr/bin/rev
-    ln -s "${xcodeBaseDir}/Contents/Developer/usr/bin/xcodebuild"
     ln -s "${xcodeBaseDir}/Contents/Developer/Applications/Simulator.app/Contents/MacOS/Simulator"
 
     cd ..
     ln -s "${xcodeBaseDir}/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs"
-
-    # Check if we have the xcodebuild version that we want
-    currVer=$($out/bin/xcodebuild -version | head -n1)
-    ${if allowHigher then ''
-    if [ -z "$(printf '%s\n' "${version}" "$currVer" | sort -V | head -n1)""" != "${version}" ]
-    '' else ''
-    if [ -z "$(echo $currVer | grep -x 'Xcode ${version}')" ]
-    ''}
-    then
-        echo "We require xcodebuild version${if allowHigher then " or higher" else ""}: ${version}"
-        echo "Instead what was found: $currVer"
-        exit 1
-    fi
   '';
 }