allows you to show a lightbox directly after dismissing on ios (#1466)

ios/RCCLightBox.m

 @property (nonatomic, strong) UIView *overlayColorView;
 @property (nonatomic, strong) NSDictionary *params;
 @property (nonatomic)         BOOL yellowBoxRemoved;
+@property (nonatomic)         BOOL isDismissing;
 @end
 
 @implementation RCCLightBoxView
 
 -(void)dismissAnimated
 {
+    self.isDismissing = YES;
+    
     BOOL hasOverlayViews = (self.visualEffectView != nil || self.overlayColorView != nil);
     
     [UIView animateWithDuration:0.2 animations:^()
 +(void)showWithParams:(NSDictionary*)params
 {
     UIViewController *viewController = RCTPresentedViewController();
-    if ([viewController.view viewWithTag:kLightBoxTag] != nil)
+    RCCLightBoxView *previousLightBox = [viewController.view viewWithTag:kLightBoxTag];
+    if (previousLightBox != nil && !previousLightBox.isDismissing)
     {
         return;
     }