Question

我正在尝试创建星级评分控件子类。我的评分控制类中有一个名为rating的可选变量，我希望在创建视图后可以对其进行更改，但是由于某些原因，该变量始终为nil。

如何在StarRatingView类中具有可以按以下示例更改的属性？

class StarRatingView: UIStackView {

    var rating: Int?

    override init(frame: CGRect) {
        super.init(frame: frame)
        print(rating) // <<<---- Prints "nil" -----
        addStarsBasedOnRating()
    }

    required init(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }


    // How I'd like to access rating <<<<-------
    func addStarsBasedOnRating() {
        if rating == someNumber {
            // do something    
        }
    }

}

这是在将其初始化的类中创建分级控件的方式。

let ratingView: StarRatingView = {
    let view = StarRatingView()
    view.rating = 4
    return view
}()

Answer 1

您正在尝试在设置值之前打印该值。试试这个：

class StarRatingView: UIStackView {

    var rating: Int? {
        didSet {
            addStarsBasedOnRating()
        }
    }

    func addStarsBasedOnRating() {
        // make sure rating is not nil
        guard let rating = rating else {
            // maybe you want to reset the view in here
            return
        }

        if rating == someNumber {
            // do something
        }
    }

}

如何设置自定义UIView属性

1 个答案: