ios8.3 - Using DDMathParser to solve string in swift -

i want pass string ddmathparser , store answer in string variable using swift. totally new ios platform dont know syntax of functions. example:

var expr = "5+9*2" //some expression var result = ddmathparser.evaluate(expr) // result of expression 

here simple example how use ddmathparser swift:

let expr = "5+9*2" nsstring let result = expr.numberbyevaluatingstring().integervalue println(result) // 23 

if need floating point results replace integervalue doublevalue.