Basic version of NSError

Inspiration from SSheldon/rust-objc-foundation#16

Co-authored-by: Rob Napier <[email protected]>

Author: madsmtm

objc2-foundation/CHANGELOG.md

@@ -17,6 +17,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * Added `NSThread` object.
 * Added `is_multi_threaded` and `is_main_thread` helper functions.
 * Added `NSProcessInfo` object.
+* Added `NSError` object.
 
 ### Changed
 * **BREAKING**: Removed the following helper traits in favor of inherent

objc2-foundation/src/error.rs

@@ -0,0 +1,34 @@
+use core::ptr::NonNull;
+
+use objc2::ffi::NSInteger;
+use objc2::msg_send;
+use objc2::rc::{Id, Shared};
+
+use crate::{NSDictionary, NSObject, NSString};
+
+pub type NSErrorUserInfoKey = NSString;
+
+#[allow(non_snake_case)]
+pub fn NSLocalizedDescriptionKey() -> Id<NSString, Shared> {
+    NSString::from_str(&"NSLocalizedDescription")
+}
+
+object!(
+    unsafe pub struct NSError: NSObject;
+);
+
+impl NSError {
+    pub fn new<T>(
+        code: NSInteger,
+        domain: Id<NSString, Shared>,
+        user_info: Id<NSDictionary<NSErrorUserInfoKey, T>, Shared>,
+    ) -> Id<Self, Shared> {
+        let cls = Self::class();
+        unsafe {
+            let obj: *mut Self = msg_send![cls, alloc];
+            let obj: *mut Self =
+                msg_send![obj, initWithDomain: &*domain, code: code, userInfo: &*user_info];
+            Id::new(NonNull::new_unchecked(obj))
+        }
+    }
+}

objc2-foundation/src/lib.rs

@@ -27,6 +27,7 @@ pub use self::copying::{NSCopying, NSMutableCopying};
 pub use self::data::{NSData, NSMutableData};
 pub use self::dictionary::NSDictionary;
 pub use self::enumerator::{NSEnumerator, NSFastEnumeration, NSFastEnumerator};
+pub use self::error::{NSError, NSErrorUserInfoKey, NSLocalizedDescriptionKey};
 pub use self::object::NSObject;
 pub use self::process_info::NSProcessInfo;
 pub use self::range::NSRange;
@@ -51,6 +52,7 @@ mod copying;
 mod data;
 mod dictionary;
 mod enumerator;
+mod error;
 mod object;
 mod process_info;
 mod range;