Vendor dependencies for 0.3.0 release

vendor/objc2/examples/introspection.rs

@@ -0,0 +1,52 @@
+use objc2::runtime::{AnyClass, NSObject};
+use objc2::{sel, ClassType, Encode};
+
+fn main() {
+    // Get the class representing `NSObject`
+    let cls = NSObject::class();
+
+    // Inspect various properties of the class
+    println!("NSObject superclass: {:?}", cls.superclass());
+    println!("NSObject size: {}", cls.instance_size());
+    println!(
+        "-[NSObject alloc] would work: {}",
+        cls.responds_to(sel!(alloc))
+    );
+    println!(
+        "+[NSObject alloc] would work: {}",
+        cls.metaclass().responds_to(sel!(alloc))
+    );
+
+    // Inspect an instance variable on the class
+    //
+    // Note: You should not rely on the `isa` ivar being available,
+    // this is only for demonstration.
+    let ivar = cls
+        .instance_variable("isa")
+        .expect("No ivar with name 'isa' found on NSObject");
+    println!(
+        "Instance variable {} has type encoding {:?}",
+        ivar.name(),
+        ivar.type_encoding()
+    );
+    assert!(<*const AnyClass>::ENCODING.equivalent_to_str(ivar.type_encoding()));
+
+    // Inspect a method of the class
+    let method = cls.instance_method(sel!(hash)).unwrap();
+    println!(
+        "-[NSObject hash] takes {} parameters",
+        method.arguments_count()
+    );
+    let hash_return = method.return_type();
+    println!("-[NSObject hash] return type: {hash_return:?}");
+    assert!(usize::ENCODING.equivalent_to_str(&hash_return));
+
+    // Create an instance
+    let obj = NSObject::new();
+
+    println!("NSObject address: {obj:p}");
+
+    // Read an ivar on the object
+    let isa: *const AnyClass = unsafe { *ivar.load(&obj) };
+    println!("NSObject isa: {isa:?}");
+}