str3 = "welcome to play swift!Step-by-Step learn from now"
str3.componentsSeparatedByCharactersInSet(NSCharacterSet(charactersInString: " !-"))

//join
var str5 = "-"
str5.join(["1","2","3"])

//range
str3.rangeOfString("Step")//(22,4)
str3.rangeOfString("Step",options:NSStringCompareOptions.BackwardsSearch)//(30,4)
str3.rangeOfString("welcome",options:NSStringCompareOptions.CaseInsensitiveSearch)//(0,7)

还是objective-C的风格