the plist file to put into /Library/LaunchDaemons to swap the ± with ~ on UK keyboard

tilde-switch.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
    "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.localhost.tilde-switch</string>
    
    <key>StandardErrorPath</key>
    <string>/tmp/tilde/tilde-err.log</string>

    <key>StandardOutPath</key>
    <string>/tmp/tilde/tilde.log</string>

    <key>RunAtLoad</key>
    <true/>

    <key>ProgramArguments</key>
    <array>             
        <string>hidutil</string>
        <string>property</string>
        <string>--set</string>
		<string>{"UserKeyMapping":[{"HIDKeyboardModifierMappingSrc":0x700000035,"HIDKeyboardModifierMappingDst":0x700000064},{"HIDKeyboardModifierMappingSrc":0x700000064,"HIDKeyboardModifierMappingDst":0x700000035}]}</string>
    </array>
    
    <key>KeepAlive</key>
    <false/>

    <!-- <key>UserName</key>
    <string>dlai</string> -->
    
</dict>
</plist>