Swift字符串截取的子范围方法

//字符串的截取

letstr ="/>Hello Merry Christmas day

//获取开头两个字符子串

letstartIndex = str.index(str.startIndex, offsetBy:2)

letstartSuffix = str.substring(to: startIndex)

print(startSuffix)

//获取结尾两个字符子串

letendIndex = str.index(str.endIndex, offsetBy:-2)

letendSuffix = str.substring(from: endIndex)

print(endSuffix)

//注意：对字符串进行截取操作，原来的字符串不变Hello Merry Christmas day

letrangeStr = str.substring(with: startIndex..

print(rangeStr)