[ffigen] Remove objc_retain from bindings (#1888)

pkgs/ffigen/CHANGELOG.md

@@ -5,6 +5,7 @@
 - Handle dart typedefs in import/export of symbol files.
 - Add support for blocking ObjC blocks that can be invoked from any thread.
 - Add support for blocking ObjC protocol methods.
+- Remove explicit `objc_retain` calls from the generated bindings.
 
 ## 16.0.0
 

pkgs/ffigen/lib/src/code_generator/objc_interface.dart

@@ -180,7 +180,8 @@ ${generateAsStub ? '' : _generateMethods(w)}
   }
 
   @override
-  String? generateRetain(String value) => 'objc_retain($value)';
+  String? generateRetain(String value) =>
+      '(__bridge id)(__bridge_retained void*)($value)';
 
   @override
   void visit(Visitation visitation) => visitation.visitObjCInterface(this);

pkgs/ffigen/lib/src/code_generator/pointer.dart

@@ -105,7 +105,7 @@ class IncompleteArray extends PointerType {
 
   @override
   String getNativeType({String varName = ''}) =>
-      '${child.getNativeType()} $varName[]';
+      '${child.getNativeType()}* $varName';
 
   @override
   String toString() => '$child[]';
@@ -153,7 +153,8 @@ class ObjCObjectPointer extends PointerType {
       '${getDartType(w)}($value, retain: $objCRetain, release: true)';
 
   @override
-  String? generateRetain(String value) => 'objc_retain($value)';
+  String? generateRetain(String value) =>
+      '(__bridge id)(__bridge_retained void*)($value)';
 
   @override
   bool isSupertypeOf(Type other) {

pkgs/ffigen/lib/src/code_generator/writer.dart

@@ -444,7 +444,6 @@ class Writer {
 #error "This file must be compiled with ARC enabled"
 #endif
 
-id objc_retain(id);
 id objc_retainBlock(id);
 ''');