init(start: end) is deprecated:

Swift3.0中的更新提示
init(start: end) is deprecated: it will be removed in Swift 3. Use the '..<' operator

init(start: end) is deprecated: it will be removed in Swift 3. Use the '..<' operator

这个提示就是让你把代码形式修改改为如下形式
Swift3.0以前写法

s2.removeRange(Range(start: s2.startIndex.advancedBy(1), end: s2.startIndex.advancedBy(3)))

Swift3.0后 写成如下格式

s2.removeRange(Range(s2.startIndex.advancedBy(1)..<s2.startIndex.advancedBy(4)))