iOS: Properly handle system gesture deferral for preferredScreenEdge (#864)

Author: usmandotmughal

platform/iphone/AppDelegate.h

@@ -40,16 +40,25 @@ namespace Rtt
 @interface AppViewController : CoronaViewController
 {
 	UIResponder *fNextResponder;
+
+    // NEW: Internal flags for gesture deferral
+    BOOL scDeferSystemGestures;   // Enable/disable flag
+    UIRectEdge scDeferEdges;      // Which edges to defer
 }
 
 - (void)setNextResponder:(UIResponder *)responder;
-
 - (BOOL)prefersStatusBarHidden;
+- (UIStatusBarStyle)preferredStatusBarStyle;
+
+- (void)setSystemGestureDeferralEnabled:(BOOL)enabled;
+- (void)setSystemGestureDeferEdges:(UIRectEdge)edges;
+- (BOOL)isSystemGestureDeferralEnabled;
+- (UIRectEdge)systemGestureDeferEdges;
 
-- (UIStatusBarStyle) preferredStatusBarStyle;
+// Override this method instead of using @property
+- (UIRectEdge)preferredScreenEdgesDeferringSystemGestures;
 
 @property (nonatomic, assign) BOOL prefersHomeIndicatorAutoHidden;
-@property (nonatomic, assign) UIRectEdge preferredScreenEdgesDeferringSystemGestures;
 @property (nonatomic, assign) bool prefersStatusBarhidden;
 @property (nonatomic, assign) UIStatusBarStyle preferredStatusBarStyle;
 

platform/iphone/AppDelegate.mm

@@ -222,17 +222,43 @@ @implementation AppViewController
 
 @synthesize preferredStatusBarStyle = _preferredStatusBarStyle;
 @synthesize prefersHomeIndicatorAutoHidden;
-@synthesize preferredScreenEdgesDeferringSystemGestures;
 
 
 - (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle
 {
-	self = [super initWithNibName:nibName bundle:nibBundle];
-	if ( self )
-	{
-		fNextResponder = nil;
-	}
-	return self;
+    self = [super initWithNibName:nibName bundle:nibBundle];
+    if ( self )
+    {
+        fNextResponder = nil;
+        scDeferSystemGestures = NO;
+        scDeferEdges = UIRectEdgeTop | UIRectEdgeBottom;  // Start with top|bottom, NOT all
+    }
+    return self;
+}
+
+- (UIRectEdge)preferredScreenEdgesDeferringSystemGestures
+{
+    return scDeferSystemGestures ? scDeferEdges : UIRectEdgeNone;
+}
+
+- (void)setSystemGestureDeferralEnabled:(BOOL)enabled
+{
+    scDeferSystemGestures = enabled;
+}
+
+- (void)setSystemGestureDeferEdges:(UIRectEdge)edges
+{
+    scDeferEdges = edges;
+}
+
+- (BOOL)isSystemGestureDeferralEnabled
+{
+    return scDeferSystemGestures;
+}
+
+- (UIRectEdge)systemGestureDeferEdges
+{
+    return scDeferEdges;
 }
 
 - (void)dealloc

platform/iphone/Rtt_IPhonePlatform.mm

@@ -1128,14 +1128,15 @@ - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
 			[viewController setNeedsUpdateOfHomeIndicatorAutoHidden];
 		}
 	}
-	else if ([k isEqualToString:@"preferredScreenEdgesDeferringSystemGestures"])
-	{
-		viewController.preferredScreenEdgesDeferringSystemGestures = lua_toboolean( L, valueIndex )?UIRectEdgeAll:UIRectEdgeNone;
-		if (@available(iOS 11.0, *))
-		{
-			[viewController setNeedsUpdateOfScreenEdgesDeferringSystemGestures];
-		}
-	}
+    else if ([k isEqualToString:@"preferredScreenEdgesDeferringSystemGestures"])
+    {
+        [viewController setSystemGestureDeferralEnabled:lua_toboolean(L, valueIndex)];
+        [viewController setSystemGestureDeferEdges:(UIRectEdgeTop | UIRectEdgeBottom)];
+        if (@available(iOS 11.0, *))
+        {
+            [viewController setNeedsUpdateOfScreenEdgesDeferringSystemGestures];
+        }
+    }
 	else
 	{
 		Super::SetNativeProperty(L, key, valueIndex);
@@ -1156,10 +1157,10 @@ - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
 	{
 		lua_pushboolean(L, viewController.prefersHomeIndicatorAutoHidden);
 	}
-	else if ([k isEqualToString:@"preferredScreenEdgesDeferringSystemGestures"])
-	{
-		lua_pushboolean(L, viewController.preferredScreenEdgesDeferringSystemGestures != UIRectEdgeNone);
-	}
+    else if ([k isEqualToString:@"preferredScreenEdgesDeferringSystemGestures"])
+    {
+        lua_pushboolean(L, [viewController isSystemGestureDeferralEnabled]);
+    }
 	else
 	{
 		result = Super::PushNativeProperty(L, key);