基于数组中的第三个索引创建userDecision

Question

    func Decision() {
    if ArrowType.index(ArrowType.startIndex, offsetBy: 3) == "<" {
        UserChoice = "L"
    } else if {ArrowType.index(ArrowType.startIndex, offsetBy: 3) == ">"           
        UserChoice = "R"
    }
}

二进制运算符'=='不能应用于类型为'String.Index'和'String'的操作数

Answer 1

ArrowType.index（ArrowType.startIndex，offsetBy：3）将返回索引值。使用以下代码获取该索引的值：

ArrowType[ArrowType.index(ArrowType.startIndex, offsetBy: 3)]