在 SwiftUI 中捕获错误

Question

我在某些视图中有一个按钮，它调用 ViewModel 中可能引发错误的函数。

Button(action: {
    do {
        try self.taskViewModel.createInstance(name: self.name)
    } catch DatabaseError.CanNotBeScheduled {
        Alert(title: Text("Can't be scheduled"), message: Text("Try changing the name"), dismissButton: .default(Text("OK")))
    }
}) {
    Text("Save")
}

try-catch 块产生以下错误：

Invalid conversion from throwing function of type '() throws -> Void' to non-throwing function type '() -> Void'

这是 viewModel 中的 createInstance 函数，taskModel 函数以完全相同的方式处理错误。

func createIntance(name: String) throws {
    do {
        try taskModel.createInstance(name: name)
    } catch {
        throw DatabaseError.CanNotBeScheduled
    }
}   

如何正确捕捉 SwiftUI 中的错误？

Answer 1

使用.alert 修饰符显示警报，如下所示

@State private var isError = false
...
Button(action: {
    do {
        try self.taskViewModel.createInstance(name: self.name)
    } catch DatabaseError.CanNotBeScheduled {
        // do something else specific here
        self.isError = true
    } catch {
        self.isError = true
    }
}) {
    Text("Save")
}
 .alert(isPresented: $isError) {
    Alert(title: Text("Can't be scheduled"),
          message: Text("Try changing the name"),
          dismissButton: .default(Text("OK")))
}