Swift属性-Getter Ivar [英] Swift property - getter ivar

问题描述

在Swift getter中是否应该使用ivar属性?我的代码导致吸气剂调用吸气剂，直到程序崩溃:

Is there an ivar property we should use in a Swift getter? My code is causing the getter to call the getter until the program crashes:

var document: UIDocument? {
    get {
        return self.document
    }
    set {
        self.document = newValue

        useDocument()
    }
}

推荐答案

Swift属性没有像在Objective-C中那样具有独立的基础存储的概念.相反，您需要创建第二个(私有)属性并将其用作存储:

Swift properties do not have the concept of separate, underlying storage like they do in Objective-C. Instead, you'll need to create a second (private) property and use that as the storage:

private var _document: UIDocument?
var document: UIDocument? {
    get {
        return _document
    }
    set {
        _document = newValue
        useDocument()
    }
}

如果您只想在设置document属性后调用useDocument()，则可以省略getter，setter和private属性，而只需使用willSet或didSet.

If all you're trying to do is call useDocument() after the document property is set, you can omit the getter, setter, and private property and instead just use willSet or didSet.

这篇关于Swift属性-Getter Ivar的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！