不推荐使用“substring(from:)":请使用带有“partial range from"运算符的字符串切片下标.斯威夫特 4 错误 [英] 'substring(from:)' is deprecated: Please use String slicing subscript with a 'partial range from' operator. Swift 4 Error

问题描述

我正在将我现有的应用程序从 Swift 3 转换为 Swift 4.它给出了错误:

I am converting my existing app from Swift 3 to Swift 4. It is giving the error:

'substring(from:)' 已弃用:请使用带有部分范围 from"运算符的字符串切片下标.

'substring(from:)' is deprecated: Please use String slicing subscript with a 'partial range from' operator.

和

'characters' 已弃用:请直接使用 String 或 Substring

'characters' is deprecated: Please use String or Substring directly

我的 Swift 3 代码是:

public convenience init?(hexString: String, alpha: Float) {
    var hex = hexString

    // Check for hash and remove the hash
    if hex.hasPrefix("#") {
        hex = hex.substring(from: hex.characters.index(hex.startIndex, offsetBy: 1))
    }

    if (hex.range(of: "(^[0-9A-Fa-f]{6}$)|(^[0-9A-Fa-f]{3}$)", options: .regularExpression) != nil) {

        // Deal with 3 character Hex strings
        if hex.characters.count == 3 {
            let redHex   = hex.substring(to: hex.characters.index(hex.startIndex, offsetBy: 1))
            let greenHex = hex.substring(with: (hex.characters.index(hex.startIndex, offsetBy: 1) ..< hex.characters.index(hex.startIndex, offsetBy: 2)))
            let blueHex  = hex.substring(from: hex.characters.index(hex.startIndex, offsetBy: 2))

            hex = redHex + redHex + greenHex + greenHex + blueHex + blueHex
        }

        let redHex = hex.substring(to: hex.characters.index(hex.startIndex, offsetBy: 2))
        let greenHex = hex.substring(with: (hex.characters.index(hex.startIndex, offsetBy: 2) ..< hex.characters.index(hex.startIndex, offsetBy: 4)))
        let blueHex = hex.substring(with: (hex.characters.index(hex.startIndex, offsetBy: 4) ..< hex.characters.index(hex.startIndex, offsetBy: 6)))

        var redInt:   CUnsignedInt = 0
        var greenInt: CUnsignedInt = 0
        var blueInt:  CUnsignedInt = 0

        Scanner(string: redHex).scanHexInt32(&redInt)
        Scanner(string: greenHex).scanHexInt32(&greenInt)
        Scanner(string: blueHex).scanHexInt32(&blueInt)

        self.init(red: CGFloat(redInt) / 255.0, green: CGFloat(greenInt) / 255.0, blue: CGFloat(blueInt) / 255.0, alpha: CGFloat(alpha))
    }
    else {
        self.init()
        return nil
    }
}

如何将其转换为 Swift 4?

推荐答案

'characters' is deprecated: Please use String or Substring directly

'characters' is deprecated: Please use String or Substring directly

为此，您可以在 swift 4 中直接遍历字符串，因此无需字符数组.

For this you can directly loop through string in swift 4 so there is no need to characters array.

为了

'substring(from:)' 已弃用:请使用带有部分范围 from"运算符的字符串切片下标.

'substring(from:)' is deprecated: Please use String slicing subscript with a 'partial range from' operator.

参考 如何在斯威夫特 4?

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