Double类的parseDouble方法, 将字符串解析为double值 String ds = "5.3739"; Double d = Double.parseDouble(ds);
//先将doubleValue转成NSString
let str = "10.0"
let double = (str as NSString).doubleValue
string.doubleValue
\\ ==> string to Double
let string = NSString(format: "%f" , double)
\\==> Double to String