tabbar hide fix (#2084)

ios/RCCTabBarController.m

@@ -344,6 +344,10 @@
   if ([performAction isEqualToString:@"setTabBarHidden"])
   {
     BOOL hidden = [actionParams[@"hidden"] boolValue];
+    
+    CGRect nextFrame = self.tabBar.frame;
+    nextFrame.origin.y = UIScreen.mainScreen.bounds.size.height - (hidden ? 0 : self.tabBar.frame.size.height);
+    
     [UIView animateWithDuration: ([actionParams[@"animated"] boolValue] ? 0.45 : 0)
                           delay: 0
          usingSpringWithDamping: 0.75
@@ -351,7 +355,7 @@
                         options: (hidden ? UIViewAnimationOptionCurveEaseIn : UIViewAnimationOptionCurveEaseOut)
                      animations:^()
      {
-       self.tabBar.transform = hidden ? CGAffineTransformMakeTranslation(0, self.tabBar.frame.size.height) : CGAffineTransformIdentity;
+         [self.tabBar setFrame:nextFrame];
      }
                      completion:^(BOOL finished)
      {