自己.在尾随的快速关闭中，意义和目的是什么? [英] self. in trailing swift closures, meaning and purpose?

问题描述

每当我在动作上使用结尾闭包时...例如:

whenever I use a trailing closure on an action ... example:

run(SKAction.wait(forDuration: 10)){timeRemains = false}

我看到了这个

在闭包中引用属性(任何内容)都需要明确的自我"使捕获语义明确.

Reference to property (anything) in closure requires explicitly ‘self’ to make capture semantics explicit.

这是什么意思?到底是关于什么的?我很好奇，因为我只在尾随闭包中调用的属性或函数的上下文/范围内执行此操作，所以不知道为什么我需要`self并着迷于

What does this mean? And what is it on about? I'm curious because I'm only ever doing this in the context/scope of the property or function I want to call in the trailing closure, so don't know why I need `self and fascinated by the use of the word

语义学"

在这里.它具有深远的意义吗?如果我理解了闭包，我会神奇地理解闭包吗?

here. Does it have some profound meaning, and will I magically understand closures if I understand this?

推荐答案

它具有深远的意义吗?如果我理解了闭包，我会神奇地理解闭包吗?

Does it have some profound meaning, and will I magically understand closures if I understand this?

不，不.也许，也许，也许.

No and no. Or perhaps, maybe and maybe.

产生这种语法要求的原因是，它实际上可能是 一个闭包，也就是说，它可能捕获并保留其引用的环境(因为您使用的是匿名函数)可能会存储一段时间.这意味着，如果您在此处引用 self 的某些属性，例如 myProperty ，则实际上是 捕获对 self的引用.Swift要求您明确地确认这一事实(通过说出 self.myProperty ，而不仅仅是 myProperty )，以便 you 了解这是正在发生的事情.

The reason for this syntactical demand is that this might really be a closure, that is, it might capture and preserve its referenced environment (because the anonymous function you are passing might be stored somewhere for a while). That means that if you refer here to some property of self, such as myProperty, you are in fact capturing a reference to self. Swift demands that you acknowledge this fact explicitly (by saying self.myProperty, not merely myProperty) so that you understand that this is what's happening.

您为什么需要了解它?因为在某些情况下，您可能会以保留周期告终，或者以其他方式以意想不到的方式保存 self 的寿命.这是一种让您思考这个事实的方法.

Why do you need to understand it? Because under some circumstances you can end up with a retain cycle, or in some other way preserving the life of self in ways that you didn't expect. This is a way of getting you to think about that fact.

((如果已知此特定函数将不充当闭包，即将被立即执行，则不存在此类危险，Swift将 not 要求您明确说出 self .)

(If it is known that this particular function will not act as a closure, i.e. that it will be executed immediately, then there is no such danger and Swift will not demand that you say self explicitly.)

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