fix(ios): Use WillEnterForeground instead of DidBecomeActive for Event::Resumed in iOS

.changes/event-resumed-change.md

@@ -0,0 +1,5 @@
+---
+"tao": minor
+---
+
+`Event::Resumed` is now only emitted when the app is actually resumed (going back to foreground) so it won't be called on app startup.

.changes/will-enter-foreground.md

@@ -0,0 +1,5 @@
+---
+"tao": patch
+---
+
+Use WillEnterForeground instead of DidBecomeActive for Event::Resumed in iOS.

src/event.rs

@@ -78,9 +78,21 @@ pub enum Event<'a, T: 'static> {
   UserEvent(T),
 
   /// Emitted when the application has been suspended.
+  ///
+  /// ## Platform-specific
+  ///
+  /// - **Android**: This is triggered by `onPause` method of the Activity.
+  /// - **iOS**: This is triggered by `applicationWillResignActive` method of the UIApplicationDelegate.
+  /// - **Linux / macOS / Windows**: Unsupported.
   Suspended,
 
   /// Emitted when the application has been resumed.
+  ///
+  /// ## Platform-specific
+  ///
+  /// - **Android**: This is triggered by `onResume` method of the Activity. The first onResume() is ignored to match the iOS implementation, since that is called on activity creation.
+  /// - **iOS**: This is triggered by `applicationWillEnterForeground` method of the UIApplicationDelegate.
+  /// - **Linux / macOS / Windows**: Unsupported.
   Resumed,
 
   /// Emitted when all of the event loop's input events have been processed and redraw processing

src/platform_impl/android/ndk_glue.rs

@@ -21,15 +21,18 @@ use std::{
   fs::File,
   io::{BufRead, BufReader},
   os::unix::prelude::*,
-  sync::{Arc, Condvar, Mutex, RwLock, RwLockReadGuard},
+  sync::{
+    atomic::{AtomicBool, Ordering},
+    Arc, Condvar, Mutex, RwLock, RwLockReadGuard,
+  },
   thread,
 };
 
 /// Android pacakge name that could be used to reference classes
 /// in the android project.
 pub static PACKAGE: OnceCell<&str> = OnceCell::new();
 
-/// Generate JNI compilant functions that are necessary for
+/// Generate JNI compliant functions that are necessary for
 /// building android apps with tao.
 ///
 /// Arguments in order:
@@ -123,6 +126,7 @@ static WINDOW_MANAGER: StaticCell<Option<GlobalRef>> = StaticCell(RefCell::new(N
 static INPUT_QUEUE: Lazy<RwLock<Option<InputQueue>>> = Lazy::new(|| Default::default());
 static CONTENT_RECT: Lazy<RwLock<Rect>> = Lazy::new(|| Default::default());
 static LOOPER: Lazy<Mutex<Option<ForeignLooper>>> = Lazy::new(|| Default::default());
+static DID_RESUME: AtomicBool = AtomicBool::new(false);
 
 pub fn window_manager() -> std::cell::Ref<'static, Option<GlobalRef>> {
   WINDOW_MANAGER.0.borrow()
@@ -285,7 +289,12 @@ pub unsafe fn create(
 }
 
 pub unsafe fn resume(_: JNIEnv, _: JClass, _: JObject) {
-  wake(Event::Resume);
+  let did_resume = DID_RESUME.swap(true, Ordering::Relaxed);
+  // first Activity onResume() is called even after onCreate()
+  // to match the iOS implementation, we ignore the first resume event
+  if did_resume {
+    wake(Event::Resume);
+  }
 }
 
 pub unsafe fn pause(_: JNIEnv, _: JClass, _: JObject) {

src/platform_impl/ios/mod.rs

@@ -50,7 +50,7 @@
 //!
 //! This is how those event are represented in tao:
 //!
-//!  - applicationDidBecomeActive is Resumed
+//!  - applicationWillEnterForeground is Resumed
 //!  - applicationWillResignActive is Suspended
 //!  - applicationWillTerminate is LoopDestroyed
 //!

src/platform_impl/ios/view.rs

@@ -611,15 +611,14 @@ pub fn create_delegate_class() {
     }
   }
 
-  extern "C" fn did_become_active(_: &Object, _: Sel, _: id) {
-    unsafe { app_state::handle_nonuser_event(EventWrapper::StaticEvent(Event::Resumed)) }
-  }
-
   extern "C" fn will_resign_active(_: &Object, _: Sel, _: id) {
     unsafe { app_state::handle_nonuser_event(EventWrapper::StaticEvent(Event::Suspended)) }
   }
 
-  extern "C" fn will_enter_foreground(_: &Object, _: Sel, _: id) {}
+  extern "C" fn will_enter_foreground(_: &Object, _: Sel, _: id) {
+    unsafe { app_state::handle_nonuser_event(EventWrapper::StaticEvent(Event::Resumed)) }
+  }
+
   extern "C" fn did_enter_background(_: &Object, _: Sel, _: id) {}
 
   extern "C" fn will_terminate(_: &Object, _: Sel, _: id) {
@@ -669,10 +668,6 @@ pub fn create_delegate_class() {
       application_continue as extern "C" fn(_, _, _, _, _) -> _,
     );
 
-    decl.add_method(
-      sel!(applicationDidBecomeActive:),
-      did_become_active as extern "C" fn(_, _, _),
-    );
     decl.add_method(
       sel!(applicationWillResignActive:),
       will_resign_active as extern "C" fn(_, _, _),