綁定必須有可選類型斯威夫特3錯誤

Question

我很感興趣，爲什麼我得到這個錯誤：

Initializer for conditional binding must have Optional type, not [String]

這裏是我的代碼：

class MainVC: UIViewController { 
    @IBOutlet weak var typesField: IQDropDownTextField! 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     let elements: Array<String?> = ["Electronics", "Cars", "Toys"] 
     typesField.isOptionalDropDown = false 
     typesField.itemList = (elements as? [String])!  
    } 

    @IBAction func savePressed(_ sender: UIButton) { 
     var item: Item! 

     if let types = typesField.itemListUI { 
      item.type = types 
     } 
    } 
} 

Answer 1

Initializer for conditional binding must have Optional type, not [String]

指的右側表達式（typesField.itemListUI）不是可選的，並且不需要可選的綁定

因此改爲

if let types = typesField.itemListUI { 
    item.type = types 
} 

只寫

item.type = typesField.itemListUI 

沒有if let，沒有多餘的局部變量。