Remove ImplicitlyUnwrappedOptional to be compatible with Swift 5

Author: PhamBaTho

Source/BTNavigationDropdownMenu.swift

@@ -294,7 +294,7 @@ open class BTNavigationDropdownMenu: UIView {
             titleToDisplay = title
         }
 
-        titleSize = (titleToDisplay as NSString).size(withAttributes: [NSAttributedString.Key.font:self.configuration.navigationBarTitleFont])
+        titleSize = (titleToDisplay as NSString).size(withAttributes: [NSAttributedString.Key.font: self.configuration.navigationBarTitleFont])
 
         // Set frame
         let frame = CGRect(x: 0, y: 0, width: titleSize.width + (self.configuration.arrowPadding + self.configuration.arrowImage.size.width)*2, height: self.navigationController!.navigationBar.frame.height)

Source/Internal/BTConfiguration.swift

@@ -31,7 +31,7 @@ final class BTConfiguration {
     var cellTextLabelColor: UIColor?
     var selectedCellTextLabelColor: UIColor?
     var cellTextLabelFont: UIFont!
-    var navigationBarTitleFont: UIFont!
+    var navigationBarTitleFont: UIFont
     var cellTextLabelAlignment: NSTextAlignment!
     var cellSelectionColor: UIColor?
     var checkMarkImage: UIImage!
@@ -45,27 +45,23 @@ final class BTConfiguration {
     var shouldChangeTitleText: Bool!
 
     init() {
-        self.defaultValue()
-    }
-    
-    func defaultValue() {
         // Path for image
         let bundle = Bundle(for: BTConfiguration.self)
         let url = bundle.url(forResource: "BTNavigationDropdownMenu", withExtension: "bundle")
         let imageBundle = Bundle(url: url!)
         let checkMarkImagePath = imageBundle?.path(forResource: "checkmark_icon", ofType: "png")
         let arrowImagePath = imageBundle?.path(forResource: "arrow_down_icon", ofType: "png")
-        
-        // Default values
+
+        // Set default values
         self.menuTitleColor = UIColor.darkGray
         self.cellHeight = 50
         self.cellBackgroundColor = UIColor.white
         self.arrowTintColor = UIColor.white
         self.cellSeparatorColor = UIColor.darkGray
         self.cellTextLabelColor = UIColor.darkGray
         self.selectedCellTextLabelColor = UIColor.darkGray
-        self.cellTextLabelFont = UIFont(name: "HelveticaNeue-Bold", size: 17)
-        self.navigationBarTitleFont = UIFont(name: "HelveticaNeue-Bold", size: 17)
+        self.cellTextLabelFont = UIFont.systemFont(ofSize: 17, weight: .bold)
+        self.navigationBarTitleFont = UIFont.systemFont(ofSize: 17, weight: .bold)
         self.cellTextLabelAlignment = NSTextAlignment.left
         self.cellSelectionColor = UIColor.lightGray
         self.checkMarkImage = UIImage(contentsOfFile: checkMarkImagePath!)