ios: adjust to latest Swift syntax

ios/sdk/sdk.xcodeproj/project.pbxproj

 				TargetAttributes = {
 					0BD906E41EC0C00300C8C18E = {
 						CreatedOnToolsVersion = 8.3.2;
-						LastSwiftMigration = 0920;
+						LastSwiftMigration = 1010;
 						ProvisioningStyle = Automatic;
 					};
 				};
 				SKIP_INSTALL = YES;
 				SWIFT_OBJC_BRIDGING_HEADER = "";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0;
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Debug;
 		};
 				PROVISIONING_PROFILE_SPECIFIER = "";
 				SKIP_INSTALL = YES;
 				SWIFT_OBJC_BRIDGING_HEADER = "";
-				SWIFT_VERSION = 3.0;
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Release;
 		};

ios/sdk/src/picture-in-picture/DragGestureController.swift

             else { return CGPoint.zero }
 
         let currentSize = view.frame.size
-        let adjustedBounds = UIEdgeInsetsInsetRect(bounds, insets)
+        let adjustedBounds = bounds.inset(by: insets)
         let threshold: CGFloat = 20.0
         let velocity = panGesture.velocity(in: view.superview)
         let location = panGesture.location(in: view.superview)
 
         let goLeft: Bool
-        if fabs(velocity.x) > threshold {
+        if abs(velocity.x) > threshold {
             goLeft = velocity.x < -threshold
         } else {
             goLeft = location.x < bounds.midX
         }
 
         let goUp: Bool
-        if fabs(velocity.y) > threshold {
+        if abs(velocity.y) > threshold {
             goUp = velocity.y < -threshold
         } else {
             goUp = location.y < bounds.midY

ios/sdk/src/picture-in-picture/PiPViewCoordinator.swift

         }
 
         // resize to suggested ratio and position to the bottom right
-        let adjustedBounds = UIEdgeInsetsInsetRect(bounds, dragBoundInsets)
+        let adjustedBounds = bounds.inset(by: dragBoundInsets)
         let size = CGSize(width: bounds.size.width * pipSizeRatio,
                           height: bounds.size.height * pipSizeRatio)
         let x: CGFloat = adjustedBounds.maxX - size.width