Built up a better system for handling data cleanup on Mac OS X; thanks to http://stackoverflow.com/questions/29522715/is-there-a-reliable-way-to-destroy-private-data-structures-when-a-standard-nsvie.

button_darwin.m

@@ -9,10 +9,13 @@
 
 @implementation uiNSButton
 
-- (void)dealloc
+- (void)viewDidMoveToSuperview
 {
-	uiDarwinControlFree(self.uiC);
+	if (uiDarwinControlFreeWhenAppropriate(self.uiC, [self superview])) {
-	[super dealloc];
+		[self setTarget:nil];
+		self.uiC = NULL;
+	}
+	[super viewDidMoveToSuperview];
 }
 
 - (IBAction)uiButtonClicked:(id)sender

container_darwin.m

@@ -10,10 +10,17 @@
 // thanks to mikeash and JtRip in irc.freenode.net/#macdev
 @implementation uiContainer
 
-uiLogObjCClassAllocations(
+uiLogObjCClassAllocations
-	if (self.child != NULL)
+
-		uiControlDestroy(self.child);
+- (void)viewDidMoveToSuperview
-)
+{
+	if ([self superview] == nil)
+		if (self.child != NULL) {
+			uiControlDestroy(self.child);
+			self.child = NULL;
+		}
+	[super viewDidMoveToSuperview];
+}
 
 - (void)setFrameSize:(NSSize)s
 {

newcontrol_darwin.m

@@ -14,7 +14,7 @@ struct uiSingleViewControl {
 
 static void singleDestroy(uiControl *c)
 {
-	[S(c)->view release];
+	[S(c)->view removeFromSuperview];
 }
 
 static uintptr_t singleHandle(uiControl *c)
@@ -90,7 +90,11 @@ uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHas
 	return (uiControl *) c;
 }
 
-void uiDarwinControlFree(uiControl *c)
+BOOL uiDarwinControlFreeWhenAppropriate(uiControl *c, NSView *newSuperview)
 {
-	uiFree(c);
+	if (newSuperview == nil) {
+		uiFree(c);
+		return YES;
+	}
+	return NO;
 }

ui_darwin.h

@@ -10,8 +10,9 @@ This file assumes that you have imported <Cocoa/Cocoa.h> and "ui.h" beforehand.
 // uiDarwinNewControl() creates a new uiControl with the given Cocoa control inside.
 // The first parameter should come from [RealControlType class].
 // The two scrollView parameters allow placing scrollbars on the new control.
-// Your control must call uiDarwinControlFree() on the returned uiControl in its -[dealloc] method.
+// Your control must call uiDarwinControlFreeWhenAppropriate() on the returned uiControl in its -[viewDidMoveToSuperview] method.
+// If it returns a value other than NO, then the uiControl has been freed and you should set references to it to NULL.
 extern uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHasBorder);
-extern void uiDarwinControlFree(uiControl *);
+extern BOOL uiDarwinControlFreeWhenAppropriate(uiControl *c, NSView *newSuperview);
 
 #endif

uipriv_darwin.h

@@ -14,7 +14,7 @@ struct uiSizing {
 // TODO see if we can override alloc instead
 #ifdef uiLogAllocations
 #import <stdio.h>
-#define uiLogObjCClassAllocations(deallocCode) \
+#define uiLogObjCClassAllocations \
 + (id)alloc \
 { \
 	id thing; \
@@ -24,17 +24,11 @@ struct uiSizing {
 } \
 - (void)dealloc \
 { \
-	deallocCode \
 	[super dealloc]; \
 	fprintf(stderr, "%p free\n", self); \
 }
 #else
-#define uiLogObjCClassAllocations(deallocCode) \
+#define uiLogObjCClassAllocations
-- (void)dealloc \
-{ \
-	deallocCode \
-	[super dealloc]; \
-}
 #endif
 
 // util_darwin.m

window_darwin.m

@@ -4,7 +4,9 @@
 // TODO
 // - showing on size
 
+// TODO clean this up
 @interface uiWindowDelegate : NSObject <NSWindowDelegate>
+@property (assign) NSWindow *win;
 @property uiWindow *w;
 @property int (*onClosing)(uiWindow *, void *);
 @property void *onClosingData;
@@ -12,7 +14,7 @@
 
 @implementation uiWindowDelegate
 
-uiLogObjCClassAllocations()
+uiLogObjCClassAllocations
 
 - (BOOL)windowShouldClose:(id)win
 {
@@ -25,6 +27,7 @@ uiLogObjCClassAllocations()
 // after this method returns we assume the window will be released (see below), so we can go too
 - (void)windowWillClose:(NSNotification *)note
 {
+	[self.win setDelegate:nil];		// see http://stackoverflow.com/a/29523141/3408572
 	uiFree(self.w);
 	[self release];
 }
@@ -63,6 +66,7 @@ uiWindow *uiNewWindow(char *title, int width, int height)
 	[w->w setContentView:((NSView *) w->container)];
 
 	w->d = [uiWindowDelegate new];
+	w->d.win = w->w;
 	w->d.w = w;
 	w->d.onClosing = defaultOnClosing;
 	[w->w setDelegate:w->d];