不符合 BindableObject 协议 - Xcode 11 Beta 4

问题描述

玩弄那里的例子.发现一个项目的类是 bindableobject 并且它没有给出任何错误.现在 Xcode 11 beta 4 已经发布，我收到了错误:

Playing around with examples out there. Found a project that had a class that was a bindableobject and it didn't give any errors. Now that Xcode 11 beta 4 is out, I'm getting the error:

类型UserSettings"不符合协议BindableObject"

它有一个关于错误的修复按钮，当你点击它时，它会添加

It has a fix button on the error which when you click on that, it adds

typealias PublisherType = <#type#>

它希望您填写类型.

类型是什么?

class UserSettings: BindableObject {

    let didChange = PassthroughSubject<Void, Never>()

    var score: Int = 0 {
        didSet {
            didChange.send()
        }
    }
}

推荐答案

Beta 4 Release笔记说:

Beta 4 Release notes say:

BindableObject 协议的要求现在是 willChange 而不是didChange，现在应该在对象改变之前发送比改变之后.此更改允许改进合并更改通知.(51580731)

您需要将代码更改为:

class UserSettings: BindableObject {

    let willChange = PassthroughSubject<Void, Never>()

    var score: Int = 0 {
        willSet {
            willChange.send()
        }
    }
}

在 Beta 5 中，他们再次更改. 这一次他们一起弃用了 BindableObject！

In Beta 5 they change it again. This time they deprecated BindableObject all together!

BindableObject 被 ObservableObject 协议取代结合框架.(50800624)

您可以通过定义一个手动符合 ObservableObject在对象更改之前发出的 objectWillChange 发布者.但是，默认情况下，ObservableObject 会自动合成objectWillChange 并在任何 @Published 属性更改之前发出.

You can manually conform to ObservableObject by defining an objectWillChange publisher that emits before the object changes. However, by default, ObservableObject automatically synthesizes objectWillChange and emits before any @Published properties change.

@ObjectBinding 被@ObservedObject 取代.

@ObjectBinding is replaced by @ObservedObject.

class UserSettings: ObservableObject {
    @Published var score: Int = 0
}

struct MyView: View {
    @ObservedObject var settings: UserSettings
}

这篇关于不符合 BindableObject 协议 - Xcode 11 Beta 4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！