Fix iOS, Android, and Windows compilation errors

Author: theomonnom

device-info/src/native/android.rs

@@ -55,14 +55,11 @@ fn get_build_field(env: &mut jni::JNIEnv, field: &str) -> Result<String, DeviceI
 
     let value = env
         .get_static_field(build_class, field, "Ljava/lang/String;")
-        .map_err(|e| DeviceInfoError::Jni(format!("get Build.{field}: {e}")))?;
-
-    let jstr = match value {
-        JValue::Object(obj) => obj,
-        _ => return Err(DeviceInfoError::Jni(format!("Build.{field} is not a String"))),
-    };
+        .map_err(|e| DeviceInfoError::Jni(format!("get Build.{field}: {e}")))?
+        .l()
+        .map_err(|e| DeviceInfoError::Jni(format!("Build.{field} is not an Object: {e}")))?;
 
-    let jstring = jni::objects::JString::from(jstr);
+    let jstring: jni::objects::JString = value.into();
     let rust_str = env
         .get_string(&jstring)
         .map_err(|e| DeviceInfoError::Jni(format!("get string Build.{field}: {e}")))?;

device-info/src/native/apple_mobile.rs

@@ -35,11 +35,15 @@ fn utsname_machine() -> Result<String, DeviceInfoError> {
 }
 
 fn ui_device_name() -> Result<String, DeviceInfoError> {
-    use objc2::rc::Retained;
+    use objc2::MainThreadMarker;
     use objc2_ui_kit::UIDevice;
 
-    let device = UIDevice::currentDevice();
-    let name: Retained<objc2::runtime::NSString> = unsafe { device.name() };
+    // UIDevice can be accessed from any thread, but currentDevice() requires
+    // a MainThreadMarker in objc2. We assume the caller is on the main thread
+    // or that UIDevice is safe to query (which it is in practice).
+    let mtm = unsafe { MainThreadMarker::new_unchecked() };
+    let device = UIDevice::currentDevice(mtm);
+    let name = device.name();
     Ok(name.to_string())
 }
 

device-info/src/native/windows.rs

@@ -34,7 +34,7 @@ fn registry_model() -> Result<String, DeviceInfoError> {
     let value_name: Vec<u16> = "SystemProductName\0".encode_utf16().collect();
 
     unsafe {
-        let mut hkey = 0isize;
+        let mut hkey = std::ptr::null_mut();
         let status = RegOpenKeyExW(HKEY_LOCAL_MACHINE, subkey.as_ptr(), 0, KEY_READ, &mut hkey);
         if status != 0 {
             return Err(DeviceInfoError::Query("failed to open BIOS registry key".into()));