我在以下任务中收到错误“条件绑定的初始化程序必须具有可选类型

在这里查看我的代码：

 

let  movieDictionary  =  [ "Spectre" :  [ "cast" :  [ "Daniel Craig" ,  "Christoph Waltz" ,  "Léa Seydoux" ,  "Ralph Fiennes" ,  "Monica Bellucci" ,  "Naomie Harris" ]]] 

var LeadActor : String = "" // 在下面输入代码if let movie = movieDictionary [ "Spectre" ], let cast = movie [ "cast"]，让演员=

            演员[ 0 ]  {

主角=演员}      

 

 

答：似乎您正试图从键“强制转换”中获取值两次 - 这是正确的方法：

 

let  movieDictionary  =  [ "Spectre" :  [ "cast" :  [ "Daniel Craig" ,  "Christoph Waltz" ,  "Léa Seydoux" ,  "Ralph Fiennes" ,  "Monica Bellucci" ,  "Naomie Harris" ]]] 

var LeadActor : String = "" if let movie = movieDictionary [ "Spectre" ], let moviecast = movie [ "cast"] {主角=电影    

          [ 0 ] 

}