DropDown background is transparent when using library iOS DropDown.

[priyavarthini]

I used the following link to import the iOSDropDown library
https://github.com/jriosdev/iOSDropDown.

I have installed iOSdropDown Library in my project and have followed all the steps. It's perfectly working except for the background of the dropdown. The background of the drop down is transparent and I have tried changing it to white. But it is still transparent. I have attached the screenshot for reference. Kindly help me on this.

This is the code I have in viewController

override func viewDidLoad() {

    super.viewDidLoad()

//reaction Type Dropdown

reactionType.optionArray   = ["Peroxide", "Diazomethane", "Sodium amide"]// The list of array to display. Can be changed dynamically
reactionType.optionIds = [1,23,54,22]
reactionType.didSelect{(selectedText , index ,id) in
 self.reactionType.text = selectedText
   
   
}

// Its Id Values and its optional

//reaction time Dropdown
reactionTime.optionArray   = ["6 hours", "12 hours", "3 hours", "24 hours"]
reactionTime.optionIds = [2,3,4,5]


//temperature range Dropdown
temperatureRange.optionArray   = ["-20 to 25C", "25 to 140C"]
temperatureRange.optionIds = [6,7,8,9]
    temperatureRange.didSelect{(selectedText , index ,id) in
        self.temperatureRange.text = selectedText
     //tempRange = self.temperatureRange.text
}

//total solvent Dropdown
totalSolvent.optionArray   = ["Up to 500mL", "Up to 100 mL", "Up to 50mL"]
totalSolvent.optionIds = [2,3,4,5]
        totalSolvent.didSelect{(selectedText , index ,id) in
            self.totalSolvent.text = selectedText
             //totSolvent = self.totalSolvent.text
        }


//Out of OfficeHours Dropdown
outofOfficeHours.optionArray   = ["option1", "option 2", "option 3"]
outofOfficeHours.optionIds = [2,3,4,5]
            outofOfficeHours.optionIds = [2,3,4,5]
            outofOfficeHours.didSelect{(selectedText , index ,id) in
                self.outofOfficeHours.text = selectedText
                 //outOfOffice = self.outofOfficeHours.text
}