Swift 为什么说guard let `self` = sel

先看官方类似用法

demo.jpg

官方解释:

原文:https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160118/007425.html

Allowing `guard let self = self else { ... }`        for weakly captured self in a closure.

> On Jan 5, 2016, at 8:21 PM, Christopher Rogers via swift-evolution <swift-evolution at swift.org> wrote:
> 
> You can shadow self with a guard like you wrote it if use the keyword escaping backquotes like so:
> 
> guard let `self` = self else { return }

To confirm what others have said down thread, this is a compiler bug: this code is valid, but shouldn’t change what references to “self.method()” or “method()" bind to (i.e., explicit or implicit references to self).

Backquotes are for forming a name that happens to overlap with a keyword.  In the case of `self`, this could be because you want to refer to the NSObject.`self` method for some reason.  Backquotes are not a way to name self, init, subscript or any of the other declarations that look like magic identifiers.

-Chris Lattner
Fri Jan 22 19:51:29 CST 2016

原文中明确指出这是一个编译器bug,反引号``不应该用在self,ini和'subscript'等这种关键字

stackoverflow.jpg

可参考Stack Overflow 上https://stackoverflow.com/questions/24468336/how-to-correctly-handle-weak-self-in-swift-blocks-with-arguments

推荐用以下写法

guard let strongSelf = self else{  ...  }

或者

if let strongSelf = self {
    ...
}

参考原文:http://www.swifthumb.com/thread-22207-1-1.html