Use a bit less unsafe on iOS (#2643)

* Use a bit less `unsafe` on iOS

I did test this in XCode 11.3's "Debug View Heirarchy", the NSStringRust problem is no longer applicable (likely because Rust got better at emitting correct debug info).

* Avoid using `id` on iOS

src/platform/ios.rs

@@ -99,17 +99,17 @@ pub trait WindowExtIOS {
 impl WindowExtIOS for Window {
     #[inline]
     fn ui_window(&self) -> *mut c_void {
-        self.window.ui_window() as _
+        self.window.ui_window()
     }
 
     #[inline]
     fn ui_view_controller(&self) -> *mut c_void {
-        self.window.ui_view_controller() as _
+        self.window.ui_view_controller()
     }
 
     #[inline]
     fn ui_view(&self) -> *mut c_void {
-        self.window.ui_view() as _
+        self.window.ui_view()
     }
 
     #[inline]

src/platform_impl/ios/app_state.rs

@@ -15,11 +15,13 @@ use core_foundation::runloop::{
     kCFRunLoopCommonModes, CFRunLoopAddTimer, CFRunLoopGetMain, CFRunLoopRef, CFRunLoopTimerCreate,
     CFRunLoopTimerInvalidate, CFRunLoopTimerRef, CFRunLoopTimerSetNextFireDate,
 };
-use objc2::foundation::{CGRect, CGSize, NSInteger};
+use objc2::foundation::{CGRect, CGSize, NSInteger, NSProcessInfo};
 use objc2::rc::{Id, Shared};
-use objc2::{class, msg_send, sel};
+use objc2::runtime::Object;
+use objc2::{msg_send, sel};
 use once_cell::sync::Lazy;
 
+use super::uikit::UIView;
 use super::view::WinitUIWindow;
 use crate::{
     dpi::LogicalSize,
@@ -27,7 +29,7 @@ use crate::{
     event_loop::ControlFlow,
     platform_impl::platform::{
         event_loop::{EventHandler, EventProxy, EventWrapper, Never},
-        ffi::{id, NSOperatingSystemVersion},
+        ffi::NSOperatingSystemVersion,
     },
     window::WindowId as RootWindowId,
 };
@@ -542,7 +544,7 @@ pub unsafe fn did_finish_launching() {
         // completed. This may result in incorrect visual appearance.
         // ```
         let screen = window.screen();
-        let _: () = msg_send![&window, setScreen: 0 as id];
+        let _: () = msg_send![&window, setScreen: ptr::null::<Object>()];
         window.setScreen(&screen);
 
         let controller = window.rootViewController();
@@ -830,14 +832,12 @@ fn handle_hidpi_proxy(
     let logical_size = physical_size.to_logical(scale_factor);
     let size = CGSize::new(logical_size.width, logical_size.height);
     let new_frame: CGRect = CGRect::new(screen_frame.origin, size);
-    unsafe {
-        let _: () = msg_send![view, setFrame: new_frame];
-    }
+    view.setFrame(new_frame);
 }
 
-fn get_view_and_screen_frame(window: &WinitUIWindow) -> (id, CGRect) {
+fn get_view_and_screen_frame(window: &WinitUIWindow) -> (Id<UIView, Shared>, CGRect) {
     let view_controller = window.rootViewController().unwrap();
-    let view: id = unsafe { msg_send![&view_controller, view] };
+    let view = view_controller.view().unwrap();
     let bounds = window.bounds();
     let screen = window.screen();
     let screen_space = screen.coordinateSpace();
@@ -971,9 +971,9 @@ impl NSOperatingSystemVersion {
 pub fn os_capabilities() -> OSCapabilities {
     static OS_CAPABILITIES: Lazy<OSCapabilities> = Lazy::new(|| {
         let version: NSOperatingSystemVersion = unsafe {
-            let process_info: id = msg_send![class!(NSProcessInfo), processInfo];
+            let process_info = NSProcessInfo::process_info();
             let atleast_ios_8: bool = msg_send![
-                process_info,
+                &process_info,
                 respondsToSelector: sel!(operatingSystemVersion)
             ];
             // winit requires atleast iOS 8 because no one has put the time into supporting earlier os versions.
@@ -984,7 +984,7 @@ pub fn os_capabilities() -> OSCapabilities {
             //
             // The minimum required iOS version is likely to grow in the future.
             assert!(atleast_ios_8, "`winit` requires iOS version 8 or greater");
-            msg_send![process_info, operatingSystemVersion]
+            msg_send![&process_info, operatingSystemVersion]
         };
         version.into()
     });

src/platform_impl/ios/event_loop.rs

@@ -14,13 +14,14 @@ use core_foundation::runloop::{
     CFRunLoopObserverCreate, CFRunLoopObserverRef, CFRunLoopSourceContext, CFRunLoopSourceCreate,
     CFRunLoopSourceInvalidate, CFRunLoopSourceRef, CFRunLoopSourceSignal, CFRunLoopWakeUp,
 };
-use objc2::foundation::MainThreadMarker;
+use objc2::foundation::{MainThreadMarker, NSString};
 use objc2::rc::{Id, Shared};
 use objc2::ClassType;
 use raw_window_handle::{RawDisplayHandle, UiKitDisplayHandle};
 
-use super::uikit::{UIApplication, UIDevice, UIScreen};
+use super::uikit::{UIApplication, UIApplicationMain, UIDevice, UIScreen};
 use super::view::WinitUIWindow;
+use super::{app_state, monitor, view, MonitorHandle};
 use crate::{
     dpi::LogicalSize,
     event::Event,
@@ -30,12 +31,6 @@ use crate::{
     platform::ios::Idiom,
 };
 
-use crate::platform_impl::platform::{
-    app_state,
-    ffi::{nil, NSStringRust, UIApplicationMain},
-    monitor, view, MonitorHandle,
-};
-
 #[derive(Debug)]
 pub(crate) enum EventWrapper {
     StaticEvent(Event<'static, Never>),
@@ -132,8 +127,8 @@ impl<T: 'static> EventLoop<T> {
             UIApplicationMain(
                 0,
                 ptr::null(),
-                nil,
-                NSStringRust::alloc(nil).init_str("WinitApplicationDelegate"),
+                None,
+                Some(&NSString::from_str("WinitApplicationDelegate")),
             );
             unreachable!()
         }

src/platform_impl/ios/ffi.rs

@@ -1,19 +1,12 @@
 #![allow(non_camel_case_types, non_snake_case, non_upper_case_globals)]
 
 use std::convert::TryInto;
-use std::ffi::CString;
-use std::os::raw::{c_char, c_int};
 
 use objc2::encode::{Encode, Encoding};
 use objc2::foundation::{NSInteger, NSUInteger};
-use objc2::runtime::Object;
-use objc2::{class, msg_send};
 
 use crate::platform::ios::{Idiom, ScreenEdge};
 
-pub type id = *mut Object;
-pub const nil: id = 0 as id;
-
 #[repr(C)]
 #[derive(Clone, Debug)]
 pub struct NSOperatingSystemVersion {
@@ -98,46 +91,3 @@ impl From<UIRectEdge> for ScreenEdge {
         ScreenEdge::from_bits(bits).expect("invalid `ScreenEdge`")
     }
 }
-
-#[link(name = "UIKit", kind = "framework")]
-extern "C" {
-    pub fn UIApplicationMain(
-        argc: c_int,
-        argv: *const c_char,
-        principalClassName: id,
-        delegateClassName: id,
-    ) -> c_int;
-}
-
-// This is named NSStringRust rather than NSString because the "Debug View Heirarchy" feature of
-// Xcode requires a non-ambiguous reference to NSString for unclear reasons. This makes Xcode happy
-// so please test if you change the name back to NSString.
-pub trait NSStringRust: Sized {
-    unsafe fn alloc(_: Self) -> id {
-        msg_send![class!(NSString), alloc]
-    }
-
-    unsafe fn initWithUTF8String_(self, c_string: *const c_char) -> id;
-    unsafe fn stringByAppendingString_(self, other: id) -> id;
-    unsafe fn init_str(self, string: &str) -> Self;
-    unsafe fn UTF8String(self) -> *const c_char;
-}
-
-impl NSStringRust for id {
-    unsafe fn initWithUTF8String_(self, c_string: *const c_char) -> id {
-        msg_send![self, initWithUTF8String: c_string]
-    }
-
-    unsafe fn stringByAppendingString_(self, other: id) -> id {
-        msg_send![self, stringByAppendingString: other]
-    }
-
-    unsafe fn init_str(self, string: &str) -> id {
-        let cstring = CString::new(string).unwrap();
-        self.initWithUTF8String_(cstring.as_ptr())
-    }
-
-    unsafe fn UTF8String(self) -> *const c_char {
-        msg_send![self, UTF8String]
-    }
-}

src/platform_impl/ios/uikit/mod.rs

@@ -2,6 +2,10 @@
 #![allow(non_snake_case)]
 #![allow(non_upper_case_globals)]
 
+use std::os::raw::{c_char, c_int};
+
+use objc2::foundation::NSString;
+
 mod application;
 mod coordinate_space;
 mod device;
@@ -28,3 +32,13 @@ pub(crate) use self::trait_collection::{UIForceTouchCapability, UITraitCollectio
 pub(crate) use self::view::{UIEdgeInsets, UIView};
 pub(crate) use self::view_controller::{UIInterfaceOrientationMask, UIViewController};
 pub(crate) use self::window::UIWindow;
+
+#[link(name = "UIKit", kind = "framework")]
+extern "C" {
+    pub fn UIApplicationMain(
+        argc: c_int,
+        argv: *const c_char,
+        principalClassName: Option<&NSString>,
+        delegateClassName: Option<&NSString>,
+    ) -> c_int;
+}

src/platform_impl/ios/uikit/view_controller.rs

@@ -1,6 +1,7 @@
 use objc2::encode::{Encode, Encoding};
 use objc2::foundation::{NSObject, NSUInteger};
-use objc2::{extern_class, extern_methods, ClassType};
+use objc2::rc::{Id, Shared};
+use objc2::{extern_class, extern_methods, msg_send_id, ClassType};
 
 use super::{UIResponder, UIView};
 
@@ -28,6 +29,10 @@ extern_methods!(
         #[sel(setNeedsUpdateOfScreenEdgesDeferringSystemGestures)]
         pub fn setNeedsUpdateOfScreenEdgesDeferringSystemGestures(&self);
 
+        pub fn view(&self) -> Option<Id<UIView, Shared>> {
+            unsafe { msg_send_id![self, view] }
+        }
+
         #[sel(setView:)]
         pub fn setView(&self, view: Option<&UIView>);
     }

src/platform_impl/ios/view.rs

@@ -18,7 +18,7 @@ use crate::{
     platform_impl::platform::{
         app_state,
         event_loop::{EventProxy, EventWrapper},
-        ffi::{id, UIRectEdge, UIUserInterfaceIdiom},
+        ffi::{UIRectEdge, UIUserInterfaceIdiom},
         window::PlatformSpecificWindowBuilderAttributes,
         DeviceId, Fullscreen,
     },
@@ -487,7 +487,7 @@ declare_class!(
     // UIApplicationDelegate protocol
     unsafe impl WinitApplicationDelegate {
         #[sel(application:didFinishLaunchingWithOptions:)]
-        fn did_finish_launching(&self, _application: &UIApplication, _: id) -> bool {
+        fn did_finish_launching(&self, _application: &UIApplication, _: *mut NSObject) -> bool {
             unsafe {
                 app_state::did_finish_launching();
             }

src/platform_impl/ios/window.rs

@@ -2,6 +2,7 @@
 
 use std::{
     collections::VecDeque,
+    ffi::c_void,
     ops::{Deref, DerefMut},
 };
 
@@ -22,7 +23,7 @@ use crate::{
     platform_impl::platform::{
         app_state,
         event_loop::{EventProxy, EventWrapper},
-        ffi::{id, UIRectEdge},
+        ffi::UIRectEdge,
         monitor, EventLoopWindowTarget, Fullscreen, MonitorHandle,
     },
     window::{
@@ -503,14 +504,14 @@ impl Window {
 
 // WindowExtIOS
 impl Inner {
-    pub fn ui_window(&self) -> id {
-        Id::as_ptr(&self.window) as id
+    pub fn ui_window(&self) -> *mut c_void {
+        Id::as_ptr(&self.window) as *mut c_void
     }
-    pub fn ui_view_controller(&self) -> id {
-        Id::as_ptr(&self.view_controller) as id
+    pub fn ui_view_controller(&self) -> *mut c_void {
+        Id::as_ptr(&self.view_controller) as *mut c_void
     }
-    pub fn ui_view(&self) -> id {
-        Id::as_ptr(&self.view) as id
+    pub fn ui_view(&self) -> *mut c_void {
+        Id::as_ptr(&self.view) as *mut c_void
     }
 
     pub fn set_scale_factor(&self, scale_factor: f64) {
@@ -613,7 +614,7 @@ impl Inner {
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct WindowId {
-    window: id,
+    window: *mut WinitUIWindow,
 }
 
 impl WindowId {
@@ -649,20 +650,6 @@ impl From<&Object> for WindowId {
     }
 }
 
-impl From<&mut Object> for WindowId {
-    fn from(window: &mut Object) -> WindowId {
-        WindowId {
-            window: window as _,
-        }
-    }
-}
-
-impl From<id> for WindowId {
-    fn from(window: id) -> WindowId {
-        WindowId { window }
-    }
-}
-
 #[derive(Clone, Default)]
 pub struct PlatformSpecificWindowBuilderAttributes {
     pub scale_factor: Option<f64>,