【已解决】Swift提示：Variable was never mutated consider changing to let constant

【背景】

Swift中的代码：

               if let handler = blocks.completionHandler {
                    var resp = HTTPResponse()
                    if let hresponse = task.response as? NSHTTPURLResponse {
                        resp.headers = hresponse.allHeaderFields as? Dictionary<String,String>
                        resp.mimeType = hresponse.MIMEType
                        resp.suggestedFilename = hresponse.suggestedFilename
                        resp.statusCode = hresponse.statusCode
                        resp.URL = hresponse.URL
                    }
                    resp.responseObject = response
                    if let code = resp.statusCode where resp.statusCode > 299 {
                        resp.error = self.createError(code)
                    }
                    handler(resp)

出错：

network/HTTPTask.swift:488:25: Variable ‘resp’ was never mutated; consider changing to ‘let’ constant

如图：

【解决过程】

1.先去多了解了解：

搜：

Variable was never mutated consider changing to let constant

参考：

swift – Variable ‘xxx’ was never mutated, consider changing to ‘let’ – Stack Overflow

如果变量本事就是不可变的

那么尽量从var改为let

这样Swift的编译器可以对let进行优化，从而获得更好的性能

再去按照要求去改为：

let resp = HTTPResponse()

即可。

【总结】

如果变量本事就是不可变的，就应该是const的，那么尽量从var改为let

->这样Swift的编译器可以对let进行优化，从而获得更好的性能。

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