Swift 3：如何将[String：AnyObject]转换为[String：String]？

Question

我要将[String: Anyobject]字典转换为[String: String]字典？ 我该怎么做？

Answer 1

简单地说，你可以这样来做：

if let castedDict = dictionary as? [String: String] { 
    print("Converted successfully: \(castedDict)") 

} else { 
    print("Failed to cast the dictionary") 
} 

Answer 2

不能转换字典直接从[String: AnyObject]到[String: String]：因为AnyObject可以在同一字典持有不同类型的值，每个这样的值项ISN” t一定可转换为String。

相反，如果可能，您需要遍历每个键值对并有条件地执行值转换为String。例如：

// (example) source dict 
let dict: [String: AnyObject] = ["foo": "1" as AnyObject, 
           "bar": 2 as AnyObject, 
           "baz": "3" as AnyObject] 

// target dict 
var targetDict = [String: String]() 
for (key, value) in dict { 
    if let value = value as? String { targetDict[key] = value } 
} // targetDict: ["foo": "1", "baz": "3"]