實在想不出怎么用一條語句既做到按字符串長度排序又可以按照首字母順序兩個同時排序，所以干脆用試試用鏈式編程，沒想到還真可以。。在swift2.0中寫的

var strArr=["d","cd","bcd","abcd","abc","ab","a"]

strArr.sort()

func compareTwoString(s1:String , s2:String)->Bool{

? ? return s1.characters.count<s2.characters.count //|| s1.characters.first<s2.characters.first

? ??

}

func compareTwoString2(s1:String , s2:String)->Bool{

? ? return s1.characters.first<s2.characters.first

? ??

}

strArr.sort(compareTwoString2).sort(compareTwoString)