swift - 无法识别 if 语句条件中使用的变量

Question

我正在尝试编写一些逻辑来简化我的代码。变量的值 (pointpb) 根据不同的输入而改变，并且根据该变量的值，将执行 if 语句。

我最初在 if 语句中声明了这个变量，但一旦我意识到它不能在该语句之外使用，我很快就改变了它。我已经使用了通常的资源。 Google、YouTube 和浏览 Apple 的文档，在代码的不同范围内声明变量等，但似乎无法找到这是为什么。

class MapViewController: UIViewController, MKMapViewDelegate {  
    var pointpb = 0

    //add icon push button action/draw select enable

    @IBAction func Addpointpb(_ sender: UIButton)
    {
        pointpb = 1
        Iconselected.textColor = UIColor.blue
        self.Iconselected.text = "Select One"
        self.Circleselect.isHidden = false
        self.Lineselect.isHidden = false
        self.Pointselelct.isHidden = false
    }

    //point selected
    @IBAction func Pointselect(_ sender: UIButton)
    {
        pointpb = 2
        self.Pointselelct.isHidden = true
        self.Circleselect.isHidden = true
        self.Lineselect.isHidden = true
        self.Addpointpb.isHidden = true
        self.Pointcancel.isHidden = false
        self.Iconselected.text = "Point"
    }

    //line selected
    @IBAction func Lineselect(_ sender: UIButton)
    {
        pointpb = 3
        self.Pointselelct.isHidden = true
        self.Circleselect.isHidden = true
        self.Lineselect.isHidden = true
        self.Addpointpb.isHidden = true
         self.Pointcancel.isHidden = false
        self.Iconselected.text = "Line"
    }

     //circle selected
    @IBAction func Circleselect(_ sender: UIButton)
    {
        pointpb = 4
        self.Pointselelct.isHidden = true
        self.Circleselect.isHidden = true
         self.Lineselect.isHidden = true
        self.Addpointpb.isHidden = true
         self.Pointcancel.isHidden = false
        self.Iconselected.text = "Circle"
    }
}

//==================================================================

//preferred code for me to use   

//point selected

@IBAction func Pointselect(_ sender: UIButton)
{
    pointpb = 2
    self.Iconselected.text = "Point"
}

//line selected
@IBAction func Lineselect(_ sender: UIButton)
{
    pointpb = 3
    self.Iconselected.text = "Line"
}

//circle selected
@IBAction func Circleselect(_ sender: UIButton)
{
    pointpb = 4
    self.Iconselected.text = "Circle"
}

//if statement

if pointpb == 2, pointpb == 3, pointpb == 4
{
    self.Pointselelct.isHidden = true
    self.Circleselect.isHidden = true
    self.Lineselect.isHidden = true
    self.Addpointpb.isHidden = true
    self.Pointcancel.isHidden = false
}

如您所见，最后三个函数的 UIButton 输入基本上做同样的事情。理想情况下，我想使用底部的代码部分。但是，如前所述，该变量不再被识别，我收到指向该 if 语句的“预期声明”错误。我觉得这是一件非常明显的事情，但显然我很愚蠢。

Answer 1

您编写 if 语句的方式更接近一次声明多个变量的语法，因此 Xcode 将其称为“预期声明”

编写 if 子句的正确方法是 if (pointpb == 2 || pointpb == 3 || pointpb == 4)

查看 Swift basics重温语法

另外，作为一个提示，您可以使用 if [2, 3, 4].contains(pointpb)

稍微简化您的 if 子句