Question

我对Swift很新。在Java / C＃中是否存在Swift中的通用无所不包的Object类？

我可以声明一个可以容纳任何东西的数组（Int / String / Character ......等）吗？

Answer 1

正如"Why is there no universal base class in Swift?"中所解释的那样，但是，有一个共同的协议，每种类型都隐式符合：Any。

// A statically typed `Any` constant, that points to a value which
// has a runtime type of `Int`
let something: Any = 5 

// An array of `Any` things
let things: [Any] = [1, "string", false]

for thing in things {
    switch thing {
    case let i as Int: consumeInt(i)
    case let s as String: consumeString(s)
    case let b as Bool: consumeBool(b)

    // Because `Any` really does mean ANY type, the compiler can't prove
    // that this switch is exhaustive, unless we have a `default`
    default: fatalError("Got an unexpected type!")
    }
}

但是，大多数时候使用Any是不明智的。在大多数情况下，受歧视的工会是更好的选择，Swift以enums的形式提供。这些确保考虑所有可能的类型：

// Using an enum with associated values creates a discriminated union
// containing the exact set of type that we wish to support, rather than `Any`
enum SomeValue { // Note: this is a bad name, but just as an example!
    case int(Int)
    case string(String)
    case bool(Bool)
}

let someValues: [SomeValue] = [.int(1), .string("string"), .bool(false)]

for value in someValues {
    switch value {
    case .int(let i): consumeInt(i)
    case .string(let s): consumeString(s)
    case .bool(let b): consumeBool(b)

    // Enums have finitely many cases, all of which we exhausted here
    // No `default` case required!
    }
}

Answer 2

您搜索的内容似乎有Any和AnyObject类型。您无法扩展它们，但您可以将任何对象强制转换为AnyObject类型并插入[AnyObject]数组。 Any更广泛，包括Int，String，Bool等。

Answer 3

不，Swift没有通用的Object Class。

Swift中有一个Object类吗？

3 个答案: