Swift-字符串字符是否唯一

题目:字符串中所有字符是否全不相同.

<pre><code>` func isUniqueChar(str:String)->Bool {

    if str.characters.count > 256 {
        return false
    }
    
    var chars:[Bool] = [Bool].init(repeating: false, count: 256)
    
    for i in 0..<str.characters.count {
        
        let temp:String = str[i] as String
        
        let index:Int = temp.toInt()
        
        if chars[index] {
            return false
        }
        
        chars[index] = true
    }
    
    return true
}`</code></pre>

测试代码:
<pre><code>`var uniqueStr:String = "FlyElephant"

var isUnique:Bool = myString.isUniqueChar(str: uniqueStr)

print("(uniqueStr)---是不是所有字符串唯一:(isUnique)")`</code></pre>