无法将类型“[String]”的值转换为预期的参数类型“[CDYelpPriceTier]?”

Cannot convert value of type '[String]' to expected argument type '[CDYelpPriceTier]?'

我正在开发一个需要我从 yelp 拨打电话的应用程序。在 yelp 调用中,我想替换 [.oneDollarSign, .twoDollarSigns] with "pricestring".
当我将代码更改为 priceTiers: pricestring

时出现以下错误

无法将“[String]”类型的值转换为预期的参数类型“[CDYelpPriceTier]?”

//Array declaration  
         var pricestring = [String]()

         //Set pricestring
          pricestring.append(".oneDollarSign, .twoDollarSigns")
        //Yelp Call
            yelpAPIClient.searchBusinesses(byTerm: "Food",
                 ....

            priceTiers: [.oneDollarSign, .twoDollarSigns], <----

            attributes: nil)

来自 CDYelpFusionKit 文档:

 price: (Optional) The pricing levels to filter the search result with. 
 Use the **CDYelpPriceTier** enum to get the list of supported pricing levels. 
 `price` can be an array of pricing levels (e.g. [.oneDollarSign, .twoDollarSigns, .threeDollarSigns] will filter the results to show businesses that are listed as $, $$, or $$$).

我需要做什么才能用变量替换 [.oneDollarSign, .twoDollarSigns]?

声明

//Array declaration
var priceLevels = [CDYelpPriceTier]()

设置

//Set pricestring
priceLevels.append(contentsOf: [.oneDollarSign, .twoDollarSigns])

并使用它

, ... priceTiers: priceLevels, ...