無法將類型'[String]'的返回表達式轉換爲返回類型'String？'/UIPickerView

Question

我正在使用一個UIPickerView並給我錯誤（不能將類型'[String]'的返回表達式轉換爲返回類型'String？'/ UIPickerView）。這是我的代碼。

// where the picker view is set up. 
let cubesToWorkWith = ["3X3", "2X2", "4X4", "5X5", "6X6", "7X7", "Skewb", "Square-One"] 
let threeByThreeArray = ["OLL", "PLL"] 
@IBOutlet weak var pickerViewOutlet: UIPickerView! 

func numberOfComponents(in pickerView: UIPickerView) -> Int { 
    return 2 
} 

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int { 
    let row = pickerView.selectedRow(inComponent: 0) 
    print("this is the pickerView\(row)") 

    switch row { 
    case 0: 
     return threeByThreeArray.count 
    default: 
     return cubesToWorkWith.count 
    } 
} 
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? { 
    switch row { 
    case 0: 
     return threeByThreeArray[row] 
    default: 
     return getArrayForRow(row: row) 
    } 
} 
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) { 
    cubeSelected = Int16(row) 
} 
func getArrayForRow(row: Int) -> [String] { 

    switch row { 
    case 0: 
     return threeByThreeArray 
    default: 
     return cubesToWorkWith 
    } 

    } 
} 
} 

，我得到的錯誤在titleForRow開關內部的情況下，在「迴歸getArrayForRow（行：行）」 感謝提前任何幫助!!!!

Answer 1

所以你缺少一些東西 首先你需要設置代理廣告的數據源sekf 並在titleForRow：你需要返回一個字符串，因此你 FUNC getArrayForRow（行：智力） - > [字符串] 需要像 FUNC getArrayForRow（行：智力） - >字符串

這裏是我的建議：

類的ViewController：UIViewController中，UIPickerViewDelegate，UIPickerViewDataSource //其中選擇器視圖設置{了。 let cubesToWorkWith = [「3X3」，「2X2」，「4X4」，「5X5」，「6X6」，「7X7」，「Skewb」，「Square-One」] let threeByThreeArray = [「OLL」，「PLL 「]

@IBOutlet weak var pickerViewOutlet: UIPickerView! 


override func viewDidLoad() { 
    super.viewDidLoad() 
    self.pickerViewOutlet.dataSource = self 
    self.pickerViewOutlet.delegate = self 

    // Do any additional setup after loading the view, typically from a nib. 
} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
    // Dispose of any resources that can be recreated. 
} 



func numberOfComponents(in pickerView: UIPickerView) -> Int { 
    return 2 
} 

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int { 
    let row = pickerView.selectedRow(inComponent: 0) 
    print("this is the pickerView\(row)") 

    switch row { 
    case 0: 
     return threeByThreeArray.count 
    default: 
     return cubesToWorkWith.count 
    } 
} 
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? { 
    switch row { 
    case 0: 
     return threeByThreeArray[row] as String 
    default: 
     return getArrayForRow(row: row) as String 
    } 
} 
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) { 
    // cubeSelected = Int16(row) 
} 

func getArrayForRow(row: Int) -> String { 

    switch row { 
    case 0: 
     return threeByThreeArray[row] 
    default: 
     return cubesToWorkWith[row] 
    } 

} 

}