我有此表达式返回一个UInt32：

let randomLetterNumber = arc4random()%26

我希望能够在此if语句中使用数字：

if letters.count > randomLetterNumber{
    var randomLetter = letters[randomLetterNumber]
}

问题是控制台给了我这个

Playground execution failed: error: <REPL>:11:18: error: could not find an overload for '>' that accepts the supplied arguments
if letters.count > randomLetterNumber{
   ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~

问题是UInt32无法与进行比较Int。我想投到randomLetterNumber一个Int。我努力了：

let randomLetterUNumber : Int = arc4random()%26
let randomLetterUNumber = arc4random()%26 as Int

这些都导致 could not find an overload for '%' that accepts the supplied arguments.

如何转换值或在if语句中使用它？