Rework pointer conversion and NSArray construction to prevent misuse.

src/foundation.jl

@@ -179,9 +179,12 @@ end
 
 NSArray() = NSArray(@objc [NSArray array]::id{NSArray})
 
-function NSArray(elements::Vector)
-    arr = @objc [NSArray arrayWithObjects:elements::Ptr{id{Object}}
-                                    count:length(elements)::NSUInteger]::id{NSArray}
+function NSArray(elements::Vector{<:NSObject})
+    arr = GC.@preserve elements begin
+        pointers = [element.ptr for element in elements]
+        @objc [NSArray arrayWithObjects:pointers::id{Object}
+                                 count:length(elements)::NSUInteger]::id{NSArray}
+    end
     return NSArray(arr)
 end
 

src/syntax.jl

@@ -269,8 +269,6 @@ macro objcwrapper(ex...)
   ex = quote
     $(ex.args...)
 
-    Base.unsafe_convert(T::Type{<:id}, dev::$instance) = convert(T, dev.ptr)
-
     # add a pseudo constructor to the abstract type that also checks for nil pointers.
     function $name(ptr::id)
       ptr == nil && throw(UndefRefError())
@@ -283,14 +281,25 @@ macro objcwrapper(ex...)
     ex = quote
       $(ex.args...)
 
-      Base.:(==)(a::$instance, b::$instance) = a.ptr == b.ptr
-      Base.hash(dev::$instance, h::UInt) = hash(dev.ptr, h)
+      Base.:(==)(a::$instance, b::$instance) = pointer(a) == pointer(b)
+      Base.hash(obj::$instance, h::UInt) = hash(pointer(obj), h)
     end
   end
 
   esc(ex)
 end
 
+Base.pointer(obj::Object) = obj.ptr
+
+# when passing a single object, we automatically convert it to a pointer
+Base.unsafe_convert(T::Type{<:id}, obj::Object) = convert(T, pointer(obj))
+
+# in the case of a vector of objects, we expect the caller to have converted them
+# XXX: it's too bad `cconvert` cannot do the `[pointer(obj) for obj in objs]` for us
+#      (because we can only derive unsafe references in `unsafe_convert`)
+Base.unsafe_convert(T::Type{<:id}, ptrs::Vector{<:id}) =
+  reinterpret(T, pointer(ptrs))
+
 
 # Property Accesors
 

test/runtests.jl

@@ -143,6 +143,8 @@ end
     @test reinterpret(NSString, arr2[1]) == "Hello"
     @test reinterpret(NSString, arr2[2]) == "World"
     @test Vector{NSString}(arr2) == arr1
+
+    @test_throws MethodError NSArray([NSUInteger(42)])
 end
 
 @testset "NSDictionary" begin