Proper way to modify buildSettings

[zlrs]

I'd like to change the build settings of a target. (specifically SWIFT_OBJC_INTEROP_MODE)

I randomly tried some ways like this, but they failed to work. (Error: com.google.devtools.build.lib.packages.NoSuchTargetException: no such target '//ios:buildSettings': target 'buildSettings' )

xcodeproj(
    name = "xcodeproj",
    build_mode = "bazel",
    project_name = "client",
    tags = ["manual"],
    top_level_targets = [
        ":client",
    ],
    xcode_configurations = {
        "Debug": {
            "buildSettings": {
                "SWIFT_OBJC_INTEROP_MODE": "objcxx",
            }
        }
    },
)