eframe: Use objc2 and its framework crates (#4395)

These are a replacement to the `objc` and `cocoa` crates.

This PR prevents:
- An extra copy when creating `NSData`
- A memory leak when creating `NSImage`
- A memory leak when creating `NSString`

And is generally a readability improvement.

Note that we define `NSApp` manually for now, the implementation in
`objc2-app-kit` is currently suboptimal and wouldn't allow you to check
whether the NSApplication has been created or not.

Related: #4219, this should nicely
coincide with the Winit `0.30` release.

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

Author: madsmtm

Cargo.lock

@@ -178,8 +178,19 @@ wgpu = { workspace = true, optional = true, features = [
 
 # mac:
 [target.'cfg(any(target_os = "macos"))'.dependencies]
-cocoa = "0.25.0"
-objc = "0.2.7"
+objc2 = "0.5.1"
+objc2-foundation = { version = "0.2.0", features = [
+  "block2",
+  "NSData",
+  "NSString",
+] }
+objc2-app-kit = { version = "0.2.0", features = [
+  "NSApplication",
+  "NSImage",
+  "NSMenu",
+  "NSMenuItem",
+  "NSResponder",
+] }
 
 # windows:
 [target.'cfg(any(target_os = "windows"))'.dependencies]

crates/eframe/Cargo.toml

@@ -203,12 +203,9 @@ fn set_title_and_icon_mac(title: &str, icon_data: Option<&IconData>) -> AppIconS
     use crate::icon_data::IconDataExt as _;
     crate::profile_function!();
 
-    use cocoa::{
-        appkit::{NSApp, NSApplication, NSImage, NSMenu, NSWindow},
-        base::{id, nil},
-        foundation::{NSData, NSString},
-    };
-    use objc::{msg_send, sel, sel_impl};
+    use objc2::ClassType;
+    use objc2_app_kit::{NSApplication, NSImage};
+    use objc2_foundation::{NSData, NSString};
 
     let png_bytes = if let Some(icon_data) = icon_data {
         match icon_data.to_png_bytes() {
@@ -222,38 +219,36 @@ fn set_title_and_icon_mac(title: &str, icon_data: Option<&IconData>) -> AppIconS
         None
     };
 
-    // SAFETY: Accessing raw data from icon in a read-only manner. Icon data is static!
+    // TODO(madsmtm): Move this into `objc2-app-kit`
+    extern "C" {
+        static NSApp: Option<&'static NSApplication>;
+    }
+
     unsafe {
-        let app = NSApp();
-        if app.is_null() {
+        let app = if let Some(app) = NSApp {
+            app
+        } else {
             log::debug!("NSApp is null");
             return AppIconStatus::NotSetIgnored;
-        }
+        };
 
         if let Some(png_bytes) = png_bytes {
-            let data = NSData::dataWithBytes_length_(
-                nil,
-                png_bytes.as_ptr().cast::<std::ffi::c_void>(),
-                png_bytes.len() as u64,
-            );
+            let data = NSData::from_vec(png_bytes);
 
             log::trace!("NSImage::initWithData…");
-            let app_icon = NSImage::initWithData_(NSImage::alloc(nil), data);
+            let app_icon = NSImage::initWithData(NSImage::alloc(), &data);
 
             crate::profile_scope!("setApplicationIconImage_");
             log::trace!("setApplicationIconImage…");
-            app.setApplicationIconImage_(app_icon);
+            app.setApplicationIconImage(app_icon.as_deref());
         }
 
         // Change the title in the top bar - for python processes this would be again "python" otherwise.
-        let main_menu = app.mainMenu();
-        if !main_menu.is_null() {
-            let item = main_menu.itemAtIndex_(0);
-            if !item.is_null() {
-                let app_menu: id = msg_send![item, submenu];
-                if !app_menu.is_null() {
+        if let Some(main_menu) = app.mainMenu() {
+            if let Some(item) = main_menu.itemAtIndex(0) {
+                if let Some(app_menu) = item.submenu() {
                     crate::profile_scope!("setTitle_");
-                    app_menu.setTitle_(NSString::alloc(nil).init_str(title));
+                    app_menu.setTitle(&NSString::from_str(title));
                 }
             }
         }

crates/eframe/src/native/app_icon.rs

@@ -47,6 +47,7 @@ deny = [
 
 skip = [
   { name = "bitflags" },       # old 1.0 version via glutin, png, spirv, …
+  { name = "block2" },         # old version via glutin->icrate
   { name = "event-listener" }, # TODO(emilk): rustls pulls in two versions of this 😭
   { name = "libloading" },     # wgpu-hal itself depends on 0.8 while some of its dependencies, like ash and d3d12, depend on 0.7
   { name = "memoffset" },      # tiny dependency
@@ -61,7 +62,7 @@ skip = [
 skip-tree = [
   { name = "criterion" },     # dev-dependency
   { name = "fastrand" },      # old version via accesskit_unix
-  { name = "foreign-types" }, # small crate. Old version via cocoa and core-graphics (winit).
+  { name = "foreign-types" }, # small crate. Old version via core-graphics (winit).
   { name = "objc2" },         # old version via accesskit_macos
   { name = "polling" },       # old version via accesskit_unix
   { name = "rfd" },           # example dependency