[SwiftUI]：ForEach 不适用于字典数组、带数组的字典

Posted 2023-02-24

【中文标题】[SwiftUI]：ForEach 不适用于字典数组、带数组的字典

【英文标题】：[SwiftUI]: ForEach is not working for array of dictionary, dictionary with array

【发布时间】：2020-03-17 13:00:56

【问题描述】：

我尝试在 SwiftUI 中遍历数组，但它不能正常工作。

我的代码：

let arr_type2  = [
                    ["type":"Temperature","Units":["°C","°F","°K"]],
                    ["type":"Length","Units":["m","km","ft","yd","mi"]],
                    ["type":"Time","Units":["sec","min","hr","day"]],
                    ["type":"Volume","Units":["ml","lt","cups","pints","gallons"]]
                    ]

ForEach(arr_type2, id: \.self)  dict in //Error
        Text("")

错误：协议类型“Any”不能符合“Hashable”，因为只有具体类型才能符合协议

我刚开始学习 SwiftUI，你能帮我保存一下吗？

感谢您宝贵的时间！

【参考方案1】：

你可以干净利落地写出来

struct Model:Hashable 
    let type:String
    let unnits:[String]


struct ContentView: View 

    let arr_type2 = [Model(type:"Temperature", unnits: ["°C","°F","°K"])]

    var body: some View 
           ForEach(arr_type2, id: \.self)  item in

            Text(item.type)
        
    

为什么检查https://www.hackingwithswift.com/books/ios-swiftui/why-does-self-work-for-foreach

【参考方案2】：

你可以像这样使用ForEach

 var body: some View 
    let arr_type2  = [
        ["type":"Temperature","Units":["°C","°F","°K"]],
        ["type":"Length","Units":["m","km","ft","yd","mi"]],
        ["type":"Time","Units":["sec","min","hr","day"]],
        ["type":"Volume","Units":["ml","lt","cups","pints","gallons"]]
    ]

    return ForEach(0..<arr_type2.count, id: \.self)  index -> AnyView in
        let units = arr_type2[index]["Units"] as! [String]
        return AnyView(VStack 
            Text(arr_type2[index]["type"] as! String)
            ForEach(0..<units.count, id: \.self)  indexUnits in
                 Text(units[indexUnits])
            

        )
    

【讨论】：

它显示错误，例如“对成员'count'的模糊引用”

@NiravPatel 请看我的编辑，这会显示每个字典中的“类型”，在 Xcode 11.3 中测试

谢谢，但我忘记了之前的问题？另外，之后如何使用相同的 ForEach 遍历 Units？

@NiravPatel 您方法中的问题是 arr_type2 的类型必须是可散列的（字典不是可散列的）。 “单位”是数组，因此您需要另一个 ForEach 来迭代它们，请参阅我编辑的答案