swift5 内购购买失败原因

多版本后，api发生了改变，现在用下面的

guard let payErro = tr.error as? SKError else{return}

var errR = ""

switch payErro.code {

case .unknown:

errR = "未知失败原因"

case .paymentCancelled:

errR = "用户手动取消"

case .clientInvalid:

errR = "客户端不支持"

default:

break