Avoid force unwrapping

Author: emrepun

StickyTabBarViewController/Classes/MainTabBarController.swift

@@ -38,19 +38,22 @@ open class StickyViewControllerSupportingTabBarController: UITabBarController, S
                                                      collapsedHeight: collapsedHeight,
                                                      animationDuration: animationDuration,
                                                      minimisedView: childViewController.minimisedView)
-        collapsableVCFlow!.tabController = self
-        view.addSubview(collapsableVCFlow!.view)
-        addChild(collapsableVCFlow!)
-        collapsableVCFlow!.view.translatesAutoresizingMaskIntoConstraints = false
-        collapsableVCFlow!.view.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
-        collapsableVCFlow!.view.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
+        guard let collapsableVCFlow = collapsableVCFlow else {
+            return
+        }
+        collapsableVCFlow.tabController = self
+        view.addSubview(collapsableVCFlow.view)
+        addChild(collapsableVCFlow)
+        collapsableVCFlow.view.translatesAutoresizingMaskIntoConstraints = false
+        collapsableVCFlow.view.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
+        collapsableVCFlow.view.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
 
-        collapsableVCFlow!.view.bottomAnchor.constraint(equalTo: tabBar.topAnchor).isActive = true
-        let heightConstraint = collapsableVCFlow!.view.heightAnchor.constraint(equalToConstant: collapsedHeight)
+        collapsableVCFlow.view.bottomAnchor.constraint(equalTo: tabBar.topAnchor).isActive = true
+        let heightConstraint = collapsableVCFlow.view.heightAnchor.constraint(equalToConstant: collapsedHeight)
         heightConstraint.isActive = true
-        collapsableVCFlow!.heightConstraint = heightConstraint
+        collapsableVCFlow.heightConstraint = heightConstraint
 
-        collapsableVCFlow!.didMove(toParent: self)
+        collapsableVCFlow.didMove(toParent: self)
     }
 
     final public func removeCollapsibleViewController(animated: Bool) {