Check match whole string using regular expressions in Swift

let data1 = "aaab";
let data2 = "aaaba";
let pattern = "\\Aa+b\\Z"
let b1 = data1.rangeOfString(pattern, options: .RegularExpressionSearch) != nil
//b1 is true
let b2 = data2.rangeOfString(pattern, options: .RegularExpressionSearch) != nil
//b2 is false