Question

任何人都可以帮我更新这个循环到swift 3.0。帮助赞赏。谢谢！

for var index = trimmedString.startIndex; index < trimmedString.endIndex; index = index.successor().successor() {

        let byteString = trimmedString.substringWithRange(Range<String.Index>(start: index, end: index.successor().successor()))
        let num = UInt8(byteString.withCString { strtoul($0, nil, 16) })
        data?.appendBytes([num] as [UInt8], length: 1)

    }

Answer 1

在Swift 3中，＆＃34;集合移动他们的索引＆＃34;，见关于斯威夫特进化的A New Model for Collections and Indices。特别是，

let toIndex = string.index(fromIndex, offsetBy: 2, limitedBy: string.endIndex)

将索引fromIndex提升2个字符位置，但仅限如果它适合有效的索引范围，并返回nil 除此以外。因此循环可以写为

let string = "0123456789abcdef"
let data = NSMutableData()

var fromIndex = string.startIndex
while let toIndex = string.index(fromIndex, offsetBy: 2, limitedBy: string.endIndex) {

    // Extract hex code at position fromIndex ..< toIndex:
    let byteString = string.substring(with: fromIndex..<toIndex)
    var num = UInt8(byteString.withCString { strtoul($0, nil, 16) })
    data.append(&num, length: 1)

    // Advance to next position:
    fromIndex = toIndex
}

print(data) // <01234567 89abcdef>

从swift 3.0删除语句的C样式，successor（）不可用

1 个答案: