Question

我刚刚转换了我的小应用程序，但我发现了这个错误： 'substring（from :)'已被弃用：请使用字符串切片下标和'partial range from'运算符

我的代码是：

    let dateObj = dateFormatterFrom.date(from: dateStringa)


    if dateObj != nil {
        cell.detailTextLabel?.text = dateFormatterTo.string(from:(dateObj!))
    } else {
        let index = thisRecord.pubDate.index(thisRecord.pubDate.startIndex, offsetBy: 5)
        cell.detailTextLabel?.text = thisRecord.pubDate.substring(from: index)
    }

Answer 1

按照以下示例修复此警告

let testStr = “Test Teja”

let finalStr = testStr.substring(to: index) // Swift 3
let finalStr = String(testStr[..<index]) // Swift 4

let finalStr = testStr.substring(from: index) // Swift 3
let finalStr = String(testStr[index...]) // Swift 4 

//Swift 3
let finalStr = testStr.substring(from: index(startIndex, offsetBy: 3)) 

//Swift 4
let reqIndex = testStr.index(testStr.startIndex, offsetBy: 3)
let finalStr = String(testStr[..<reqIndex])

Answer 2

取代substring使用suffix。使用如下：

cell.detailTextLabel?.text = String(thisRecord.pubDate.suffix(from: index))

Answer 3

这意味着您应该使用新的部分范围运算符作为upperBound：

let str =  "Hello World !!!"
if let index = str.range(of: "Hello ")?.upperBound {
   let string = String(str[index...])  // "World !!!"
}

在你的情况下

cell.detailTextLabel?.text = String(thisRecord.pubDate[index...]))

Answer 4

我的大部分字符串都有A-Za-z和0-9内容。不需要困难索引处理。 String的这个扩展基于熟悉的LEFT / MID和RIGHT函数。

extension String {

    // LEFT
    // Returns the specified number of chars from the left of the string
    // let str = "Hello"
    // print(str.left(3))         // Hel
    func left(_ to: Int) -> String {
        return "\(self[..<self.index(startIndex, offsetBy: to)])"
    }

    // RIGHT
    // Returns the specified number of chars from the right of the string
    // let str = "Hello"
    // print(str.left(3))         // llo
    func right(_ from: Int) -> String {
        return "\(self[self.index(startIndex, offsetBy: self.length-from)...])"
    }

    // MID
    // Returns the specified number of chars from the startpoint of the string
    // let str = "Hello"
    // print(str.left(2,amount: 2))         // ll
    func mid(_ from: Int, amount: Int) -> String {
        let x = "\(self[self.index(startIndex, offsetBy: from)...])"
        return x.left(amount)
    }
}

Answer 5

如果您希望获得具有特定偏移量且没有上限的子字符串，请执行以下操作：

let index = thisRecord.pubDate.index(thisRecord.pubDate.startIndex, offsetBy: 5)
cell.detailTextLabel?.text = String(thisRecord.pubDate[index...]

通过这种方式，您可以从现有的String创建一个新的String thisRecord.pubDate对象，并从指定的索引到原始String的结束索引中的任何内容。

Answer 6

* hard nofile 990000
* soft nofile 990000
root hard nofile 990000
root soft nofile 990000

上面的代码是“部分范围自” 看看这个How can I use String slicing subscripts in Swift 4?

Answer 7

在Swift 5中，它是：

extension String {

    func index(from: Int) -> Index {
        return self.index(startIndex, offsetBy: from)
    }

    func substring(from: Int) -> String {
        let fromIndex = index(from: from)
        return String(self[fromIndex...])
    }

    func substring(to: Int) -> String {
        let toIndex = index(from: to)
        return String(self[..<toIndex])
    }

    func substring(with r: Range<Int>) -> String {
        let startIndex = index(from: r.lowerBound)
        let endIndex = index(from: r.upperBound)
        return String(self[startIndex..<endIndex])
    }
}

不推荐使用Swift 4'substring（from :)'：请使用字符串切片下标和'partial range from'运算符

7 个答案: