swift--使用 is 和 as 操作符来实现类型检查和转换 / AnyObject与Any的区别

声明几个类：

//动物类
class Animal{

}
//陆地动物类
class terricole: Animal {

}
//海洋动物类
class SeaAnimals: Animal {

}

1，is 用来做类型检查

let cat = terricole()
let fish = SeaAnimals()
let arr = [cat,fish]

for anima in arr {
if anima is terricole{
print("这是陆地动物")
}else if anima is SeaAnimals{
print("这是海洋动物")
}
}

2, as 用来做类型转换(注：如果不确定类型转换能否成功，可以在 as 后面加问号 “?”)

for animas in arr {
if let c = animas as? terricole{
print("这是陆地动物")
}else if let w = animas as? SeaAnimals{
print("这是海洋动物")
}
}

3，AnyObjective：代表任何class类型的对象实例

let dogs = terricole()
let shark = SeaAnimals()
let arrs:[AnyObject] = [dogs,shark]

for animaes in arrs {
if let d = animaes as? terricole{
print("这是个爬行动物")
}else if let e = animaes as? SeaAnimals{
print("这是个水生动物")
}
}

4, Any：范围更广，代表处函数外任何类型的实例

var myAry:[Any] = [Any]()
myAry.append(1)
myAry.append("hero11223")
myAry.append(terricole())
myAry.append(SeaAnimals())
print("\(myAry)")
for any in myAry {
switch any {
case let any as Int:
print("这是个int类型")
case let any as String:
print("这是个String类型")
case let any as terricole:
print("这是个陆地动物类型")
case let any as SeaAnimals:
print("这是个水生动物类型")
default:
print("这是个未知类型")
}
}

打印如下：