默认参数值错误:“实例成员不能用于类型视图控制器"

默认参数值错误:“实例成员不能用于类型视图控制器

问题描述：

在我的视图控制器中:

class FoodAddViewController: UIViewController, UIPickerViewDataSource, UITextFieldDelegate, UIPickerViewDelegate {

    let TAG = "FoodAddViewController"

    // Retreive the managedObjectContext from AppDelegate
    let managedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext

    @IBOutlet weak var foodName: UITextField!

    @IBOutlet weak var foodPortion: UITextField!

    @IBOutlet weak var foodCalories: UITextField!

    @IBOutlet weak var foodUnit: UILabel!

    @IBOutlet weak var unitPicker: UIPickerView!

    @IBOutlet weak var unitPickerViewContainer: UIVisualEffectView!

    /*
        unrelated code has been ommited
    */
    func validateAllTextFields(textFields: [UITextField] = [foodName as UITextField, foodPortion, foodCalories]) -> Bool {

        var result = true
        for textField in textFields {
            result = validateTextField(textField) && result
        }
        return result
    }

    func validateTextField(textField: UITextField) -> Bool{
        let correctColor = UIColor.redColor().CGColor, normalColor = UIColor.blackColor().CGColor
        var correct = true

        if textField == foodPortion || textField == foodCalories{
            if !Misc.isInteger(textField.text!){
                correct = false
            }
        }
        if textField.text!.isEmpty {
            correct = false
        }

        textField.layer.borderColor = correct ? normalColor : correctColor

        return correct
    }
}

我有几个文本字段，在我的validateTextField中可以一次验证一个，我希望我的validateAllTextFields能够通过一一检查它们来验证给定的文本字段列表，如果没有给出列表，我想要检查包含所有三个文本字段的给定默认列表.

I have a few textfields, and in my validateTextField can verify one at a time, and I want my validateAllTextFields be able to verify a give list of textfield by checking them one by one, if the list is not given, I want to check a given default list that contains all three textfield.

我想象的代码如下:

func validateAllTextFields(textFields: [UITextField] = [foodName as UITextField, foodPortion, foodCalories]) -> Bool {

    var result = true
    for textField in textFields {
        result = validateTextField(textField) && result
    }
    return result
}

然而 Xcode 返回一个错误:

However Xcode gives an error back:

实例成员不能用于类型视图控制器

instance member cannot be used on type viewcontroller

原因是什么以及如何解决?

What's the cause and how to fix?

答

不能在函数声明中使用实例变量.使用 textFields 数组调用该函数并传递参数.

You cannot use instance variables in function declarations. Call the function with your textFields array and pass the parameters.

func validateAllTextFields(textFields: [UITextField] ) -> Bool {

    var result = true
    for textField in textFields {
        result = validateTextField(textField) && result
    }
    return result
}

有人在你的班上:

validateAllTextFields(textFields: [foodName, foodPortion, foodCalories])

或者你检查你的函数内部是否 textFields 为空而不是你使用实例变量

Or you check inside of your function if textFields is empty and than u use the instance variables

func validateAllTextFields(textFields: [UITextField] ) -> Bool {
    if textFields.count == 0 {
        textFields = [foodName, foodPortion, foodCalories]
    }
    var result = true
    for textField in textFields {
        result = validateTextField(textField) && result
    }
    return result
}

默认参数值错误:“实例成员不能用于类型视图控制器"

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