【背景】
Swift中的代码：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | 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：
1 | 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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