chore: make iOS app build work with Xcode 16.4+ (#1065)

* Add zlib and libpng dependencies with BUILD files

- Add minimal BUILD file for zlib and libpng under `third_party`.
- Override zlib and libpng as http_archive dependencies in WORKSPACE.
- Update zlib and libpng versions for Xcode 16.4 compatibility.

* Enable ARM NEON optimizations for libpng on arm64 platforms

* Format WORKSPACE file

* Update iOS CI to use macOS 15 runner

* Update zlib and libpng dependencies with SHA256 checksums

* Refactor libpng BUILD file to add iOS-specific ARM64 configs and consolidate ARM NEON optimizations

* Update iOS CI to use iPhone 16 Pro with runtime `iphonesimulator18.5`

* Pin pip to version 25.1 in iOS CI post-clone script to ensure compatibility.

* Add Python 3.14 installation in iOS CI post-clone script

* Add `brew link` step for Python 3.14 in iOS CI post-clone script

* Update iOS CI post-clone script to explicitly use Python 3.14

Author: anhappdev

.github/workflows/ios-build-test.yml

@@ -9,8 +9,8 @@ on:
 jobs:
   build:
     name: Build and test iOS app
-    # https://github.com/actions/runner-images/blob/main/images/macos/macos-14-arm64-Readme.md
-    runs-on: macos-14
+    # https://github.com/actions/runner-images/blob/main/images/macos/macos-15-arm64-Readme.md
+    runs-on: macos-15
     timeout-minutes: 180
     env:
       PERF_TEST: true
@@ -65,7 +65,7 @@ jobs:
       - name: Setup iOS simulator
         env:
           DEVICE_NAME: "iPhone 16 Pro"
-          RUNTIME_SDK: "iphonesimulator18.2"
+          RUNTIME_SDK: "iphonesimulator18.5"
         run: |
           cd flutter/ios/ci_scripts/ && bash setup_simulator.sh
           open -a Simulator

WORKSPACE

@@ -26,6 +26,26 @@ tf_patch_finder(
     workspace_dir = __workspace_dir__,
 )
 
+# Override zlib and png version to make it compatible with Xcode 16.4
+http_archive(
+    name = "zlib",
+    build_file = "//third_party:zlib.BUILD",
+    sha256 = "17e88863f3600672ab49182f217281b6fc4d3c762bde361935e436a95214d05c",
+    strip_prefix = "zlib-1.3.1",
+    urls = [
+        "https://github.com/madler/zlib/releases/download/v1.3.1/zlib-1.3.1.tar.gz",
+        "https://github.com/madler/zlib/archive/refs/tags/v1.3.1.tar.gz",
+    ],
+)
+
+http_archive(
+    name = "png",
+    build_file = "//third_party:libpng.BUILD",
+    sha256 = "71158e53cfdf2877bc99bcab33641d78df3f48e6e0daad030afe9cb8c031aa46",
+    strip_prefix = "libpng-1.6.50",
+    urls = ["https://github.com/glennrp/libpng/archive/refs/tags/v1.6.50.tar.gz"],
+)
+
 load("@tf_patch_finder//:patch_win_arm64.bzl", "PATCH_FILE")
 
 http_archive(

flutter/ios/ci_scripts/ci_post_clone.sh

@@ -64,8 +64,11 @@ echo "$MC_LOG_PREFIX protobuf version:" && protoc --version
 brew install cocoapods || brew install cocoapods || brew install cocoapods
 echo "$MC_LOG_PREFIX cocoapods version:" && pod --version
 
-echo "$MC_LOG_PREFIX python version:" && python3 --version
-python3 -m pip install --break-system-packages \
+brew install [email protected] || brew install [email protected] || brew install [email protected]
+brew link --overwrite [email protected]
+echo "$MC_LOG_PREFIX python version:" && python3.14 --version
+
+python3.14 -m pip install --break-system-packages \
   "numpy>=1.23,<2.0" \
   "absl-py>=1.3,<2.0"
 

third_party/BUILD

@@ -0,0 +1,70 @@
+# Description:
+#   libpng is the official PNG reference library.
+
+licenses(["notice"])  # BSD/MIT-like license
+
+genrule(
+    name = "pnglibconf",
+    srcs = ["scripts/pnglibconf.h.prebuilt"],
+    outs = ["pnglibconf.h"],
+    cmd = "cp $(location scripts/pnglibconf.h.prebuilt) $(location pnglibconf.h)",
+)
+
+config_setting(
+    name = "target_arm64",
+    constraint_values = ["@platforms//cpu:arm64"],
+)
+
+# Apple iOS CPU-based config_settings to avoid host/target mix-ups under split transitions.
+config_setting(
+    name = "cpu_ios_arm64",
+    values = {"cpu": "ios_arm64"},
+)
+
+cc_library(
+    name = "png",
+    srcs = [
+        "png.c",
+        "pngdebug.h",
+        "pngerror.c",
+        "pngget.c",
+        "pnginfo.h",
+        ":pnglibconf",
+        "pngmem.c",
+        "pngpread.c",
+        "pngpriv.h",
+        "pngread.c",
+        "pngrio.c",
+        "pngrtran.c",
+        "pngrutil.c",
+        "pngset.c",
+        "pngstruct.h",
+        "pngtrans.c",
+        "pngwio.c",
+        "pngwrite.c",
+        "pngwtran.c",
+        "pngwutil.c",
+    ] + select({
+        ":cpu_ios_arm64": [
+            "arm/arm_init.c",
+            "arm/filter_neon_intrinsics.c",
+            "arm/palette_neon_intrinsics.c",
+        ],
+        "//conditions:default": [],
+    }),
+    hdrs = [
+        "png.h",
+        "pngconf.h",
+    ],
+    includes = ["."],
+    linkopts = select({
+        "@bazel_tools//src/conditions:windows": [],
+        "//conditions:default": ["-lm"],
+    }),
+    copts = select({
+        ":cpu_ios_arm64": ["-DPNG_ARM_NEON_OPT=2"],
+        "//conditions:default": ["-DPNG_ARM_NEON_OPT=0"],
+    }),
+    visibility = ["//visibility:public"],
+    deps = ["@zlib//:zlib"],
+)

third_party/libpng.BUILD

@@ -0,0 +1,33 @@
+# Minimal BUILD for zlib used by TensorFlow and this project.
+
+cc_library(
+    name = "zlib",
+    srcs = [
+        "adler32.c",
+        "compress.c",
+        "crc32.c",
+        "deflate.c",
+        "gzclose.c",
+        "gzlib.c",
+        "gzread.c",
+        "gzwrite.c",
+        "infback.c",
+        "inflate.c",
+        "inffast.c",
+        "inftrees.c",
+        "trees.c",
+        "uncompr.c",
+        "zutil.c",
+    ],
+    hdrs = [
+        "zconf.h",
+        "zlib.h",
+    ],
+    includes = ["."],
+    # On POSIX (darwin, linux, android) unistd.h exists; on Windows it doesn't.
+    copts = select({
+        "@bazel_tools//src/conditions:windows": [],
+        "//conditions:default": ["-DZ_HAVE_UNISTD_H"],
+    }),
+    visibility = ["//visibility:public"],
+)