swift-string,Int,Double相互转换

var str = "Hello, playground"
//  1 字符串转Int Double Float
var str1 = "818"
//  转Int
var val1 = Int(str1);
//  转Double
var val2 = Double(str1);
//  转Float
var val3 = Float(str1);
//  如果25.0 转Int，则需要先转为Double类型再将其转换为Int类型
var val4 = "25.0"
let count = Double(val4);
let varl_int = Int(count);
print(val3!);

var num1 = 25;
var str2 = "\(num1)";
//  如果是Int类型的话 直接进行转