swift 代码退出APP swift指令

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definitely 2024-01-09 23:50:05

文章标签 swift 代码退出APP 设计模式 python java swift 文章分类 Swift 移动开发

swift 命令

In this article, we will learn about the Command design pattern and implement it in an Xcode Playground.

在本文中，我们将学习Command设计模式并在Xcode Playground中实现它。

In short, the Command is a behavioral design pattern that helps us encapsulate actions (commands) and execute them at a later point in time.

简而言之，命令是一种行为设计模式，可以帮助我们封装动作 (命令)并在以后的某个时间点执行。

It involves the following components:

它包含以下组件：

Invoker — an object that executes its commands 调用器 -执行其命令的对象
Command — an action that needs to be performed 命令 -需要执行的操作
Receiver — an object that is being acted upon. 接收器 -正在作用的对象。

(Let’s Start)

Consider an example of a moderator who reviews an app. The moderation process may have different states: inReview, approved, and rejected. We want to set specific commands for the moderator and execute them one-by-one with some delay. So let’s start creating the required components.

考虑一个审核应用程序的主持人的示例。审核过程可能具有不同的状态： inReview ， approved和rejected 。我们要为主持人设置特定的命令，并在延迟的情况下一对一地执行它们。因此，让我们开始创建所需的组件。

(Receiver)

Our receiver is an App class that has a dependency on the ModerationState. Its initial state is submittedForReview:

我们的接收者是一个依赖于ModerationState的App类。其初始状态为submittedForReview ：

Next, let’s create a Command.

接下来，让我们创建一个Command 。

(Command)

We start with a base class that each specific command with inherit from:

我们从一个基类开始，每个特定的命令都继承自该基类：

The command depends on the single App object that we will mutate accordingly in subclasses. Now let’s create these subclasses:

该命令取决于我们将在子类中进行相应突变的单个App对象。现在让我们创建这些子类：

As we can see, each command changes the moderationState property of the App object inside the execute() method.

如我们所见，每个命令都会在execute()方法中更改App对象的moderationState属性。

With commands done, now we need to create an Invoker.

完成命令后，现在我们需要创建一个Invoker 。

(Invoker)

We create the Moderator class that will act an invoker of the aforementioned commands. It has a [ModerationCommand] array and an App object. Once its commands property is set, it starts reviewing the App by executing each command with some delay. Using a DispatchSemaphore we allow only one command to be executed at a time:

我们创建了Moderator类，它将充当上述命令的调用者。它具有一个[ModerationCommand]数组和一个App对象。一旦设置了commands属性，它就会通过延迟执行每个命令来开始检查App 。使用DispatchSemaphore我们一次只允许执行一个命令：

Now we can test what we have created. Let’s initialize the Moderator and provide it with four moderation commands as follows:

现在，我们可以测试所创建的内容。让我们初始化Moderator并为其提供四个主持命令，如下所示：

As expected, the following messages are printed in the console, each after a specific delay:

如预期的那样，以下消息会在控制台中打印，每个消息都会经过特定的延迟：

We have implemented the Command design pattern.

我们已经实现了Command设计模式。