Question

当我遇到这个问题时，我正在研究Swift上的这个教程。

码

var languagesLearned: String = "3"
if let num: Int? = Int(languagesLearned)
{
    print("It is a number")
}
else
{
    print("It is not a number")
}

错误：

Playground execution failed: /var/folders/f7/0j8dbxls0kv0l9d6jwk30f2h0000gn/T/lldb/20598/playground134.swift:72:20: error: cannot invoke 'init' with an argument of type '@lvalue String'
if let num: Int? = Int(languagesLearned)
                   ^~~~~~~~~~~~~~~~~~~~~

我找不到任何关于我为何会遇到此类错误的信息。我也不知道它对init的评价。

答案后更正的代码

var languagesLearned: String = "3"
var languagesLearnedNum = languagesLearned.toInt()
if let num = languagesLearnedNum
{
    print("It is a number")
}
else
{
    print("It is not a number")
}

Answer 1

在Swift 1.x中，使用：

languagesLearned.toInt()

Int（）类型转换时，Playground执行失败

1 个答案: