diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 748b23a..65fd430 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,19 +6,14 @@ on:
   pull_request:
 jobs:
   test:
-    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }}
+    name: Julia ${{ matrix.version }} - ${{ matrix.arch }}
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
-        version:
-          - '1.6'
-          - '1'
-          - nightly
-        os:
-          - macOS-latest
-        arch:
-          - x64
+        version: ['1.6', '1.7', '1.8', '1.9', '^1.10.0-rc1']
+        os: ['macOS-latest']
+        arch: [x64]
     steps:
       - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@v1
diff --git a/src/ObjectiveC.jl b/src/ObjectiveC.jl
index 80c4833..7674b61 100644
--- a/src/ObjectiveC.jl
+++ b/src/ObjectiveC.jl
@@ -28,8 +28,9 @@ include("syntax.jl")
 
 # API wrappers
 include("foundation.jl")
+include("core_foundation.jl")
 include("dispatch.jl")
-export Foundation, Dispatch
+export Foundation, CoreFoundation, Dispatch
 
 # High-level functionality
 include("classes.jl")
diff --git a/src/core_foundation.jl b/src/core_foundation.jl
new file mode 100644
index 0000000..dff2435
--- /dev/null
+++ b/src/core_foundation.jl
@@ -0,0 +1,300 @@
+module CoreFoundation
+
+using ..ObjectiveC
+using ..CEnum
+
+
+# CFBase
+
+export CFIndex, CFRange
+
+const Boolean = Cchar
+const UniChar = Cushort
+
+if sizeof(Int) == 8
+    const CFIndex = Clonglong
+else
+    const CFIndex = Clong
+end
+
+struct CFRange
+    location::CFIndex
+    length::CFIndex
+end
+
+if sizeof(Int) == 8
+    const CFOptionFlags = Culonglong
+else
+    const CFOptionFlags = Culong
+end
+
+
+# CFAllocator
+
+export CFAllocator, default_allocator, system_default_allocator,
+       malloc_allocator, malloc_zone_allocator, null_allocator,
+       allocate!, reallocate!, deallocate!, preferred_size
+
+struct __CFAllocator end
+const CFAllocatorRef = Ptr{__CFAllocator}
+
+struct CFAllocator
+    ref::CFAllocatorRef
+end
+Base.unsafe_convert(::Type{CFAllocatorRef}, alloc::CFAllocator) = alloc.ref
+
+default_allocator() = CFAllocator(C_NULL)
+system_default_allocator() = CFAllocator(unsafe_load(cglobal(:kCFAllocatorSystemDefault, CFAllocatorRef)))
+malloc_allocator() = CFAllocator(unsafe_load(cglobal(:kCFAllocatorMalloc, CFAllocatorRef)))
+malloc_zone_allocator() = CFAllocator(unsafe_load(cglobal(:kCFAllocatorMallocZone, CFAllocatorRef)))
+null_allocator() = CFAllocator(unsafe_load(cglobal(:kCFAllocatorNull, CFAllocatorRef)))
+
+function allocate!(allocator::CFAllocator, size, hint=0)
+    @ccall CFAllocatorAllocate(
+        allocator::CFAllocatorRef,
+        size::CFIndex,
+        hint::CFOptionFlags
+    )::Ptr{Cvoid}
+end
+
+function reallocate!(allocator::CFAllocator, ptr, size, hint=0)
+    @ccall CFAllocatorReallocate(
+        allocator::CFAllocatorRef,
+        ptr::Ptr{Cvoid},
+        size::CFIndex,
+        hint::CFOptionFlags
+    )::Ptr{Cvoid}
+end
+
+function deallocate!(allocator::CFAllocator, ptr)
+    @ccall CFAllocatorDeallocate(
+        allocator::CFAllocatorRef,
+        ptr::Ptr{Cvoid}
+    )::Cvoid
+end
+
+function preferred_size(allocator::CFAllocator, size, hint=0)
+    @ccall CFAllocatorGetPreferredSizeForSize(
+        allocator::CFAllocatorRef,
+        size::CFIndex,
+        hint::CFOptionFlags
+    )::CFIndex
+end
+
+
+# CFString
+
+export CFString
+
+# TODO: toll-free bridging with NSString
+
+struct __CFString end
+const CFStringRef = Ptr{__CFString}
+
+struct CFString
+    ref::CFStringRef
+end
+Base.unsafe_convert(::Type{CFStringRef}, str::CFString) = str.ref
+
+Base.length(str::CFString) = ccall(:CFStringGetLength, CFIndex, (CFStringRef,), str)
+
+function Base.getindex(str::CFString, i::Int)
+    @boundscheck if i < 1 || i > length(str)
+        throw(BoundsError(str, i))
+    end
+    Char(ccall(:CFStringGetCharacterAtIndex, UniChar, (CFStringRef, CFIndex), str, i-1))
+end
+
+# encodings
+@cenum CFStringEncoding::UInt32 begin
+    EncodingMacRoman = 0
+    EncodingWindowsLatin1 = 0x0500
+    EncodingISOLatin1 = 0x0201
+    EncodingNextStepLatin = 0x0B01
+    EncodingASCII = 0x0600
+    EncodingUnicode = 0x0100
+    EncodingUTF8 = 0x08000100
+    EncodingNonLossyASCII = 0x0BFF
+    EncodingUTF16 = 0x0100
+    EncodingUTF16BE = 0x10000100
+    EncodingUTF16LE = 0x14000100
+    EncodingUTF32 = 0x0c000100
+    EncodingUTF32BE = 0x18000100
+    EncodingUTF32LE = 0x1c000100
+end
+
+# conversion to Julia string
+function Base.String(str::CFString)
+    len = length(str)
+    buf = Vector{UInt16}(undef, len)
+    ccall(:CFStringGetCharacters, Nothing, (CFStringRef, CFRange, Ptr{UniChar}), str, CFRange(0, len), buf)
+    String(Char.(buf))
+end
+Base.string(str::CFString) = String(str)
+
+# conversion from ASCII Julia string
+function CFString(str::String)
+    ref = @ccall CFStringCreateWithCString(
+        default_allocator()::CFAllocatorRef,
+        str::Cstring,
+        EncodingUTF8::CFStringEncoding
+    )::CFStringRef
+    CFString(ref)
+end
+Base.cconvert(::Type{CFStringRef}, str::String) = CFString(str)
+
+function Base.show(io::IO, str::CFString)
+    print(io, "CFString(\"", String(str), "\")")
+end
+
+
+# CFDate
+
+export CFTimeInterval
+
+const CFTimeInterval = Cdouble
+
+
+# CFRunLoop
+
+export CFRunLoop, current_loop, main_loop, run_loop, wake_loop, stop_loop, loop_waiting
+
+const CFRunLoopMode = CFStringRef
+
+default_loop_mode() = CFString(unsafe_load(cglobal(:kCFRunLoopDefaultMode, CFStringRef)))
+common_loop_modes() = CFString(unsafe_load(cglobal(:kCFRunLoopCommonModes, CFStringRef)))
+
+@cenum CFRunLoopRunResult::Int32 begin
+    RunLoopRunFinished = 1
+    RunLoopRunStopped = 2
+    RunLoopRunTimedOut = 3
+    RunLoopRunHandledSource = 4
+end
+
+struct __CFRunLoopSourceContext end
+const CFRunLoopRef = Ptr{__CFRunLoopSourceContext}
+
+struct CFRunLoop
+    ref::CFRunLoopRef
+end
+Base.unsafe_convert(::Type{CFRunLoopRef}, loop::CFRunLoop) = loop.ref
+
+current_loop() = CFRunLoop(ccall(:CFRunLoopGetCurrent, CFRunLoopRef, ()))
+main_loop() = CFRunLoop(ccall(:CFRunLoopGetMain, CFRunLoopRef, ()))
+
+run_loop() = ccall(:CFRunLoopRun, Nothing, ())
+
+function run_loop(seconds; mode=default_loop_mode(), return_after_source_handled=false)
+    ccall(:CFRunLoopRunInMode, CFRunLoopRunResult, (CFRunLoopMode, CFTimeInterval, Boolean), mode, seconds, return_after_source_handled)
+end
+
+wake_loop(loop::CFRunLoop) = ccall(:CFRunLoopWakeUp, Nothing, (CFRunLoopRef,), loop)
+stop_loop(loop::CFRunLoop) = ccall(:CFRunLoopStop, Nothing, (CFRunLoopRef,), loop)
+loop_waiting(loop::CFRunLoop) = ccall(:CFRunLoopIsWaiting, Boolean, (CFRunLoopRef,), loop) != 0
+
+
+# CFDictionary
+
+export CFDictionary
+
+struct __CFDictionary end
+const CFDictionaryRef = Ptr{__CFDictionary}
+
+struct CFDictionary
+    ref::CFDictionaryRef
+end
+Base.unsafe_convert(::Type{CFDictionaryRef}, dict::CFDictionary) = dict.ref
+
+
+# CFNotificationCenter
+
+export CFNotificationCenter, local_notify_center, darwin_notify_center,
+       CFNotificationObserver, add_observer!, remove_observer!, remove_every_observer!,
+       post_notification!
+
+const CFNotificationName = CFStringRef
+
+struct __CFNotificationCenter end
+const CFNotificationCenterRef = Ptr{__CFNotificationCenter}
+
+struct CFNotificationCenter
+    ref::CFNotificationCenterRef
+end
+Base.unsafe_convert(::Type{CFNotificationCenterRef}, center::CFNotificationCenter) = center.ref
+
+local_notify_center() = CFNotificationCenter(ccall(:CFNotificationCenterGetLocalCenter, CFNotificationCenterRef, ()))
+
+darwin_notify_center() =
+    CFNotificationCenter(ccall(:CFNotificationCenterGetDarwinNotifyCenter, CFNotificationCenterRef, ()))
+
+const CFNotificationCallback = Ptr{Cvoid}   # @cfunction is untyped
+
+@cenum CFNotificationSuspensionBehavior::CFIndex begin
+    SuspensionBehaviorDrop = 1
+    SuspensionBehaviorCoalesce = 2
+    SuspensionBehaviorHold = 3
+    SuspensionBehaviorDeliverImmediately = 4
+end
+
+mutable struct CFNotificationObserver
+    callback::Base.Callable
+end
+
+function observer_callback(center, observer_ptr, name, object, user_info)
+    observer = Base.unsafe_pointer_to_objref(observer_ptr)
+    observer.callback(CFNotificationCenter(center), CFString(name), object,
+                      CFDictionary(user_info))
+    return
+end
+
+function add_observer!(center::CFNotificationCenter, observer::CFNotificationObserver;
+                       name=nothing, object=nothing,
+                       suspension_behavior=SuspensionBehaviorDeliverImmediately)
+    callback_ptr = @cfunction(observer_callback, Nothing, (CFNotificationCenterRef, Ptr{Cvoid},
+                              CFNotificationName, Ptr{Cvoid}, CFDictionaryRef))
+    @ccall CFNotificationCenterAddObserver(
+        center::CFNotificationCenterRef,
+        Base.pointer_from_objref(observer)::Ptr{Cvoid},
+        callback_ptr::CFNotificationCallback,
+        something(name, C_NULL)::CFNotificationName,
+        something(object, C_NULL)::Ptr{Cvoid},
+        suspension_behavior::CFNotificationSuspensionBehavior
+    )::Cvoid
+
+    return
+end
+
+function remove_observer!(center::CFNotificationCenter, observer::CFNotificationObserver;
+                          name=nothing, object=nothing)
+    if name === nothing && object === nothing
+        @ccall CFNotificationCenterRemoveEveryObserver(
+            center::CFNotificationCenterRef,
+            Base.pointer_from_objref(observer)::Ptr{Cvoid}
+        )::Cvoid
+    else
+        @ccall CFNotificationCenterRemoveObserver(
+            center::CFNotificationCenterRef,
+            Base.pointer_from_objref(observer)::Ptr{Cvoid},
+            something(name, C_NULL)::CFNotificationName,
+            something(object, C_NULL)::Ptr{Cvoid}
+        )::Cvoid
+    end
+end
+
+@cenum NotificationFlags::CFOptionFlags begin
+    DeliverImmediately = 1
+    PostToAllSessions = 2
+end
+
+function post_notification!(center::CFNotificationCenter, name;
+                            object=nothing, user_info=nothing, options=0)
+    @ccall CFNotificationCenterPostNotificationWithOptions(
+        center::CFNotificationCenterRef,
+        name::CFNotificationName,
+        something(object, C_NULL)::Ptr{Cvoid},
+        something(user_info, C_NULL)::CFDictionaryRef,
+        options::CFOptionFlags
+    )::Cvoid
+end
+
+end
diff --git a/src/syntax.jl b/src/syntax.jl
index 5044e8b..8d2cc65 100644
--- a/src/syntax.jl
+++ b/src/syntax.jl
@@ -471,6 +471,7 @@ macro objcproperties(typ, ex)
         push!(current.args, :($final))
       end
       getproperties_ex = quote
+          # XXX: force const-prop on field, without inlining everything?
           function Base.getproperty(object::$(esc(typ)), field::Symbol)
             $getproperties_ex
           end
@@ -503,6 +504,7 @@ macro objcproperties(typ, ex)
         push!(current.args, :($final))
       end
       setproperties_ex = quote
+          # XXX: force const-prop on field, without inlining everything?
           function Base.setproperty!(object::$(esc(typ)), field::Symbol, value::Any)
             $setproperties_ex
           end
diff --git a/test/runtests.jl b/test/runtests.jl
index 3a24ca2..c263492 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -243,6 +243,108 @@ end
 
 end
 
+@testset "core foundation" begin
+
+using .CoreFoundation
+
+@testset "allocator" begin
+    allocator = default_allocator()
+
+    size = 100
+    @test preferred_size(allocator, size) >= size
+    mem = allocate!(allocator, size)
+    mem = reallocate!(allocator, mem, size*2)
+    deallocate!(allocator, mem)
+
+    # other allocators aren't directly usable, but do test their constructors
+    @test system_default_allocator() !== nothing
+    @test malloc_allocator() !== nothing
+    @test malloc_zone_allocator() !== nothing
+    @test null_allocator() !== nothing
+end
+
+@testset "strings" begin
+    str = CFString("foobar")
+    @test str[1] == 'f'
+    @test_throws BoundsError str[0]
+    @test_throws BoundsError str[7]
+    @test length(str) == 6
+    @test String(str) == "foobar"
+    @test string(str) == "foobar"
+    @test sprint(show, str) == "CFString(\"foobar\")"
+end
+
+@testset "run loop" begin
+    loop = current_loop()
+    @test loop == main_loop()
+    wake_loop(loop)
+    stop_loop(loop)
+    @test loop_waiting(loop) == false
+
+    @test run_loop(0.1) == CoreFoundation.RunLoopRunTimedOut
+end
+
+@testset "notifications" begin
+    for center in [local_notify_center(), darwin_notify_center()]
+        foo_calls = 0
+        bar_calls = 0
+        foobar_calls = 0
+        foo_observer = CFNotificationObserver() do center, name, object, info
+            foo_calls += 1
+        end
+        bar_observer = CFNotificationObserver() do center, name, object, info
+            bar_calls += 1
+        end
+        foobar_observer = CFNotificationObserver() do center, name, object, info
+            foobar_calls += 1
+        end
+
+        try
+            add_observer!(center, foo_observer; name="foo")
+            add_observer!(center, foobar_observer; name="foo")
+            add_observer!(center, bar_observer; name="bar")
+            add_observer!(center, foobar_observer; name="bar")
+
+            post_notification!(center, "foo")
+            run_loop(1; return_after_source_handled=true)
+            @test foo_calls == 1
+            @test foobar_calls == 1
+
+            post_notification!(center, "bar")
+            run_loop(1; return_after_source_handled=true)
+            @test bar_calls == 1
+            @test foobar_calls == 2
+
+            # test unsubscribing from a specific notification
+            remove_observer!(center, foobar_observer; name="foo")
+
+            post_notification!(center, "foo")
+            run_loop(1; return_after_source_handled=true)
+            @test foo_calls == 2
+            @test foobar_calls == 2
+
+            post_notification!(center, "bar")
+            run_loop(1; return_after_source_handled=true)
+            @test bar_calls == 2
+            @test foobar_calls == 3
+
+            # test unsubscribing from all notifications
+            remove_observer!(center, foobar_observer)
+
+            post_notification!(center, "bar")
+            run_loop(1; return_after_source_handled=true)
+            @test bar_calls == 3
+            @test foobar_calls == 3
+        finally
+            remove_observer!(center, foo_observer)
+            remove_observer!(center, bar_observer)
+            remove_observer!(center, foobar_observer)
+        end
+    end
+end
+
+end
+
 @testset "tracing" begin
     ObjectiveC.enable_tracing(true)
     cmd = ```$(Base.julia_cmd()) --project=$(Base.active_project())