swift2 - "Variable 'xxx' was never mutated; consider changing to 'let' constant" ERROR -
i have following problem. use code below , issue
"variable 'characteristic' never mutated; consider changing 'let' constant"
for var characteristic:cbcharacteristic in service.characteristics ?? [] { print(str) _selectedperipheral!.writevalue(str.datausingencoding(nsutf8stringencoding)!, forcharacteristic: characteristic, type: cbcharacteristicwritetype.withoutresponse) }
when change "let", there's error:
'let' pattern cannot appear nested in immutable context
why recommend me change , afterwards mark error?
you need remove var
, making code:
for characteristic in service.characteristics ?? [] { print(str) _selectedperipheral!.writevalue(str.datausingencoding(nsutf8stringencoding)!, forcharacteristic: characteristic, type: cbcharacteristicwritetype.withoutresponse) }
because characteristic
immutable default.
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