Swift 3.0 字符串的处理

删除（或替换）字符串中的某个字符

let string = "123,45 67"
//检查是否包含字符串“，”
if string.contains(","){
//删除字符串（用空""替换字符串）
let str = string.replacingOccurrences(of: ",", with: "")
print(str) //str = "12345 67"
//去除空格
str = string.replacingOccurrences(of: " ", with: "")
}

2.截取字符串

let total = "qwer"
let index = total.index(total.endIndex, offsetBy: -1) 
let totalStr = total.substring(to: index)
//totalStr 输出：qwe

3.小数点后几位

 let str = String(format: "%.2f", 12121.3223)
 //输出：12121.32