Python: Use cibuildwheel for iOS wheel builds

Replace the manual iOS cross-compilation setup (mobile-forge, PYO3_CONFIG_FILE,
custom RUSTFLAGS, _PYTHON_HOST_PLATFORM) with cibuildwheel v3, which handles
iOS Python framework setup and maturin integration automatically.

This avoids the pyo3 0.28 issue where extension-module now forces -lpython
linking on iOS (PR slint-ui#5605), which conflicts with iOS's framework packaging.

Author: tronical

.github/workflows/upload_pypi.yaml

@@ -75,32 +75,12 @@ jobs:
                 path: api/python/slint/wheelhouse/*.whl
 
     ios_binaries:
-        strategy:
-            matrix:
-                target:
-                    - aarch64-apple-ios-sim
-                    - aarch64-apple-ios
-                include:
-                    - target: aarch64-apple-ios-sim
-                      sim_suffix: SIM_
-                      python_sim_suffix: _x86_64-simulator
-                      arch: arm64
-                      sdk_name: iphonesimulator
-                      tag: ios_13_0_arm64_iphonesimulator
-                    - target: aarch64-apple-ios
-                      arch: arm64
-                      sdk_name: iphoneos
-                      tag: ios_13_0_arm64_iphoneos
-
         runs-on: macos-14
         steps:
             - uses: actions/checkout@v6
             - uses: ./.github/actions/setup-rust
               with:
-                  target: aarch64-apple-ios
-            - uses: actions/setup-python@v6
-              with:
-                python-version: '3.13'
+                  target: "aarch64-apple-ios aarch64-apple-ios-sim"
             - uses: baptiste0928/cargo-install@v3
               with:
                   crate: taplo-cli
@@ -115,36 +95,20 @@ jobs:
                 rm Cargo.toml.new
                 taplo get -f Cargo.toml features.default
 
-            - run: |
-                export GIT_LFS_SKIP_SMUDGE=1
-                git clone https://github.com/beeware/mobile-forge.git
-                cd mobile-forge
-                source ./setup-iOS.sh 3.13
-                PYTHONDIR="$PWD/support/3.13/iOS/Python.xcframework/ios-arm64${{ matrix.python_sim_suffix}}"
-                echo PYTHONDIR="$PYTHONDIR" >> $GITHUB_ENV
-                OSX_SDKROOT=$(xcrun --sdk macosx --show-sdk-path)
-                echo "OSX_SDKROOT=$OSX_SDKROOT" >> $GITHUB_ENV
-                IOS_SDKROOT=$(xcrun --sdk ${{ matrix.sdk_name }} --show-sdk-path)
-                echo "IOS_SDKROOT=$IOS_SDKROOT" >> $GITHUB_ENV
-                echo "PYO3_CROSS_PYTHON_VERSION=3.13" >> $GITHUB_ENV
-                echo "SDKROOT=$OSX_SDKROOT" >> $GITHUB_ENV
-                echo "PYO3_CROSS_LIB_DIR=$PYTHONDIR" >> $GITHUB_ENV
-                echo CARGO_TARGET_AARCH64_APPLE_IOS_${{ matrix.sim_suffix }}RUSTFLAGS="-C link-arg=-isysroot -C link-arg=$IOS_SDKROOT -C link-arg=-arch -C link-arg=${{ matrix.arch }} -C link-arg=-miphoneos-version-min=14.0 -C link-arg=-F -C link-arg=$PYTHONDIR -C link-arg=-framework	-C link-arg=Python" >> $GITHUB_ENV
-
-            - name: Build a binary wheel
-              uses: PyO3/maturin-action@v1
-              env:
-                  _PYTHON_HOST_PLATFORM: ${{ matrix.tag }}
+            - name: Build iOS wheels
+              uses: pypa/cibuildwheel@v3.4.0
               with:
-                  working-directory: api/python/slint
-                  target: ${{ matrix.target }}
-                  args: --release --out wheelhouse --interpreter 3.13
+                  package-dir: api/python/slint
+                  output-dir: wheelhouse
+              env:
+                  CIBW_PLATFORM: ios
+                  CIBW_ARCHS: arm64_iphoneos arm64_iphonesimulator
 
             - name: Store the distribution packages
               uses: actions/upload-artifact@v7
               with:
-                name: python-package-distributions-${{ matrix.target }}
-                path: api/python/slint/wheelhouse/*.whl
+                name: python-package-distributions-ios
+                path: wheelhouse/*.whl
 
     build_source_package:
         name: Build source package

api/python/slint/pyproject.toml

@@ -50,6 +50,10 @@ cache-keys = [{ file = "pyproject.toml" }, { file = "Cargo.toml" }, { file = "**
 # Uncomment to build rust code in development mode
 # config-settings = { build-args = '--profile=dev' }
 
+[tool.cibuildwheel.ios]
+# Expose Rust toolchain to the restricted iOS build environment
+xbuild-tools = ["rustc", "cargo", "rustup", "cc", "ar"]
+
 [tool.maturin]
 editable-profile = "dev"
 # added so it includes in wheel build to overrite the default behavior of not including untracked files