1.以下面代码为情境代码
class Shape{
}
class Circle:Shape{
}
class Rectangle:Shape{
}
var shape = Shape()
var circle = Circle()
var rect = Rectangle()
var array = Array<Any>()
array.append(circle)
array.append(shape)
array.append(rect)
array.append("aaaa")
array.append({return "aaaaa"})
2.is 用来判断对象是否属于某个类或者其子类,相当于OC中的isKindOf方法
for item in array{
if item is Rectangle{
print("Rectangle:\(item)")
}else if item is Circle{
print("Circle:\(item)")
}
}
3.as as? as! 转换
- as? 转换成功之后是一个optional类型的值,转换失败为nil
let s1 = shape as? Circle
s1.dynamicType
- as! 转换成功后是原类型不是目标类型，转换失败报错
let s2 = array.first as! Shape
s2.dynamicType //Circle.Type
//let s3 = array.first as! Rectangle //报错
- as 当编译器也知道一定能转成功的时候可以用as
//方式一
let s4 = shape as Shape
s4.dynamicType
//方式二
for item in array{
switch item {
case is Circle:
print("circle")
case is Rectangle:
print("rectangle")
case let s3 as Shape:
print(s3)
default:
break
}
}
