swift，使用未解析的标识符

Question

我有一个快速的代码

if(pendingComboOperation == nil){
    if(accumulator != nil){
        let descPart2 = symbol + String(accumulator!)
    }
    else {
        let descPart2 = ""
    }

}
else {
    let descPart2 = symbol + addBrackets(to: pendingComboOperation!.descPart2)
}

pendingComboOperation = PendingComboOperation(descPart1: description!, descPart2: descPart2)

并出现错误：

  

使用未解析的标识符＆＃39; descPart2＆＃39;

为什么呢？我该如何解决？

Answer 1

您无法在if或else语句中声明变量。解决方案是给descPart2一个默认值：

var descPart2: String

if(pendingComboOperation == nil){
    if(accumulator != nil){
        descPart2 = symbol + String(accumulator!)
    } else {
        descPart2 = ""
    }

} else {
    descPart2 = symbol + addBrackets(to: pendingComboOperation!.descPart2)
}

pendingComboOperation = PendingComboOperation(descPart1: description!, descPart2: descPart2)