根据值更改Swift中语句的类型

class Animal {
    func makeSound() {
        print("Animal makes sound")
    }
}

class Dog: Animal {
    override func makeSound() {
        print("Dog barks")
    }
}

let animal: Animal = Dog()
if let dog = animal as? Dog {
    dog.makeSound() // 输出 "Dog barks"
}

class Animal {
    func makeSound() {
        print("Animal makes sound")
    }
}

class Dog: Animal {
    override func makeSound() {
        print("Dog barks")
    }
}

let dog: Dog = Dog()
let animal: Animal = dog
animal.makeSound() // 输出 "Dog barks"

let value = 10
if value % 2 == 0 {
    let result = "偶数"
    print(result) // 输出 "偶数"
} else {
    let result = 1
    print(result) // 输出 1
}