獲取Swift 3中字典的值，其中鍵不是字符串

Question

我有一本字典使用NSIndexPath作爲鍵。它適用於Swift 2，但我找不到解決方案使其與Swift 3一起工作。我不想將String用作關鍵字，因此請不要提示它。

// init 
fileprivate var cachedCellSizes: [NSIndexPath: CGSize] = [:] 

// get value 
if let size = cachedCellSizes[indexPath] { 
    return size 
} 

編譯器錯誤：

Ambiguous reference to member 'subscript' 

一些解決方案，我都試過，但不起作用：

if let size:CGSize = cachedCellSizes[indexPath] as? CGSize { 
    return size 
} 
if let size:CGSize = cachedCellSizes[indexPath] as! CGSize { 
    return size 
} 
if let size:CGSize = cachedCellSizes["indexPath"] as CGSize { 
    return size 
} 

Answer 1

fileprivate var cachedCellSizes: [NSIndexPath: CGSize] = [:] 

if let size = cachedCellSizes[indexPath as NSIndexPath] { 
    print(indexPath) 
} 

OR

fileprivate var cachedCellSizes: [IndexPath: CGSize] = [:] 

if let size = cachedCellSizes[indexPath] { 
    print(indexPath) 
}