我正在尝试使用泛型创建一个通用的 UI 选择器。作为实现的一部分,我创建了要在 UIPicker 中显示的 GenericRow 对象。但我面临一些问题。这可能是基本的,但找不到。
struct GenericRow<T> {
let type: T
let title: String
public init(type: T, title: String) {
self.type = type
self.title = title
}
}
接下来是 GenericDataSource 来处理 UIPickerViewDataSource 和 UIPickerViewDelegate。
class GenericPickerDataSource<T>: NSObject, UIPickerViewDelegate, UIPickerViewDataSource {
public var items: [GenericRow<T>]
public init(withItems items: [GenericRow<T>]) {
self.items = items
}
public func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return items.count
}
public func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return items[row].title
}
}
然后,我正在创建一个管理器来处理选择器显示/隐藏功能。请注意,这也是通用的,并且不了解有关 GenericRow 类型的任何信息。
class GenericPickerManager {
static func showPicker(_ dataSource: GenericPickerDataSource<Any>) {}
static func hidePicker() {}
}
输入示例:
struct State {
let identifier: String
let name: String
}
let CA = State(identifier: "CA", name: "California")
let CLT = State(identifier: "CLT", name: "Charlotte")
let IL = State(identifier: "IL", name: "Illinois")
let states = [CA, CLT, IL]
let items = states.map {
GenericRow<State>(type: $0, title: $0.name)
}
let dataSource = GenericPickerDataSource(withItems: items)
现在,当我尝试显示类(class)中的选择器时,出现错误。
GenericPickerManager.showPicker(dataSource)
Cannot convert value of type GenericPickerDataSource<State> to expected argument type GenericPickerDataSource<Any>.
如何解决这个问题?
最佳答案
Any
和泛型不能很好地协同工作。使 GenericPickerManager
也通用:
class GenericPickerManager<T> {
static func showPicker(_ dataSource: GenericPickerDataSource<T>) {}
static func hidePicker() {}
}
关于ios - Swift 中的泛型选择器 View ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54054874/