1、oc比较:

-(BOOL) isKindOfClass: classObj判断是否是这个类或者这个类的子类的实例

-(BOOL) isMemberOfClass: classObj 判断是否是这个类的实例

2、is 类型检查

Use the type check operator (is) to check whether an instance is of a certain subclass type.

3、 (as? or as!) 类型转化

Use the conditional form of the type cast operator (as?) when you are not sure if the downcast will succeed.

Use the forced form of the type cast operator (as!) only when you are sure that the downcast will always succeed.

确信与不确信转化。

4、Type Casting for Any and AnyObject

Swift provides two special types for working with nonspecific types:

  • Any can represent an instance of any type at all, including function types.

  • AnyObject can represent an instance of any class type.

To discover the specific type of a constant or variable that is known only to be of type Any or AnyObject, you can use an is or as pattern in a switch statement’s cases. The

The Any type represents values of any type, including optional types. Swift gives you a warning if you use an optional value where a value of type Any is expected. If you really do need to use an optional value as an Anyvalue, you can use the as operator to explicitly cast the optional to Any, as shown below.

  1. let optionalNumber: Int? = 3
  2. things.append(optionalNumber) // Warning
  3. things.append(optionalNumber as Any) // No warning

swift语言点评十九-类型转化与检查的更多相关文章

  1. swift语言点评十八-异常与错误

    1.错误类型与枚举的结合 enum VendingMachineError: Error { case invalidSelection case insufficientFunds(coinsNee ...

  2. swift语言点评十六-Initialization && Deinitialization

    initial value:必须初始化.不影响观察者 Classes and structures must set all of their stored properties to an appr ...

  3. swift语言点评十四-继承

    Overriding A subclass can provide its own custom implementation of an instance method, type method, ...

  4. swift语言点评十-Value and Reference Types

    结论:value是拷贝,Reference是引用 Value and Reference Types Types in Swift fall into one of two categories: f ...

  5. swift语言点评十五-$0

    import UIKitimport XCPlayground class ViewController: UIViewController { func action() { print(" ...

  6. swift语言点评十二-Subscripts

    Classes, structures, and enumerations can define subscripts, which are shortcuts for accessing the m ...

  7. Swift语言指南(十)--字符串与字符

    原文:Swift语言指南(十)--字符串与字符 字符串是一段字符的有序集合,如"hellow,world"或"信天翁".Swift 中的字符串由 String ...

  8. swift语言点评二十-扩展

    结论:扩展无法修改原来的数据结构. Extensions can add new functionality to a type, but they cannot override existing ...

  9. swift语言点评二

    一.数据类型 1.基础类型的封装 Swift provides its own versions of all fundamental C and Objective-C types, includi ...

随机推荐

  1. Android饼图的简单实现

    1.简单的实现效果图: 2.自定义View的实现 package myapplication.com.myapp.view; import android.content.Context; impor ...

  2. mysql面试几个问题

    1.为什么InnoDB表最好要有自增列做主键? InnoDB引擎表是基于B+树的索引组织表(IOT) 关于B+树 (图片来源于网上) B+ 树的特点: a.所有关键字都出现在叶子结点的链表中(稠密索引 ...

  3. Node_进阶_1

    第一天 1.1简介 Node.js简介 V8引擎本身就是用于Chrome浏览器的JS解释部分,Ryan Dahl把这个V8搬到了服务器上,用于做服务器的软件. Node.js是一个让Javascrip ...

  4. [读书笔记] Python 数据分析 (十一)经济和金融数据应用

    resample: 重采样函数,可以按照时间来提高或者降低采样频率,fill_method可以使用不同的填充方式. pandas.data_range 的freq参数枚举: Alias Descrip ...

  5. swoole 清除定时器提示no timer

    首页确定一个核心概念 clearTimer仅可清除当前进程的定时器 server代码如下: <?php class Server { private $serv; private $timer; ...

  6. vue文件目录结构

    使用node和npm环境,很容易搭建起一个vue环境.搭建完成以后,项目基本结构,如下图所示: 1.build: bulid文件夹保存的是一些webpack的初始化配置 2.config: confi ...

  7. 紫书 例题8-1 UVa 120(构造法)

    #include<cstdio> #include<iostream> #include<sstream> #include<algorithm> #d ...

  8. JS中的Set 与去重

    -----------------------Set 与去重----------------------- ES6 提供了新的数据结构 Set.它类似于数组,但是成员的值都是唯一的,没有重复的值.Se ...

  9. nginx虚拟主机的配置不生效

    这个坑找了好久,今天终于找到了问题所在. 一般虚拟主机配置文件是vhost里面单独写一个网站名.conf,然后在nginx最后include vhosts/*.conf 引用. 但是我这里的vhost ...

  10. [using_microsoft_infopath_2010]Chapter2 表单需求,使用表决矩阵

    本章概要 1.从模板创建表单 2.从创建表单收集需求 3.使用全部表单决策 4.决定需要创建哪种表单