将类类型作为函数参数传递并用作？上课

帕特里克

有没有办法通过函数传递类类型并尝试将类转换为给定的类类型？我尝试了以下代码。

class Section {}
class TimeSection: Section {}
class TaskSection: Section {}

let timeSection = TimeSection()
let taskSection = TaskSection()

let sections = [timeSection, taskSection]

func findSection(from classType: Section.Type) {
    for section in sections {
        guard let section = section as? classType else { continue }

        print("Found section")
    }
}

findSection(from: TimeSection.self)

但是我总是会收到这个错误：

Use of undeclared type 'classType'

劳斯伯特

斯威夫特4.2

您可以使用泛型函数并将type参数限制为Section。

import Foundation

class Section {}
class TimeSection: Section {}
class TaskSection: Section {}
class NoSection {}

let timeSection = TimeSection()
let taskSection = TaskSection()

let sections = [timeSection, taskSection]

func findSection<T: Section>(from classType: T.Type) {
    for section in sections {
        guard let section = section as? T else { continue }

        print("Found section: \(section)")
    }
}

findSection(from: TimeSection.self) // Found section: __lldb_expr_9.TimeSection
findSection(from: TaskSection.self) // Found section: __lldb_expr_9.TaskSection
findSection(from: NoSection.self) // won't compile

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