HumanString is a package that let you use integers but not String.Index to specify ranges in strings.
let str = "今天天氣好清爽"
XCTAssertTrue(str[0] == "今")
XCTAssertTrue(str[4] == "好")
XCTAssertTrue(str[-1] == "爽")
XCTAssertTrue(str[0..<2] == "今天")
XCTAssertTrue(str[0...2] == "今天天")
XCTAssertTrue(str[-3 ..< -1] == "好清")
XCTAssertTrue(str[-3 ... -1] == "好清爽")
XCTAssertTrue(str[-3 ... 0] == nil)
XCTAssertTrue(str[-3 ..< 0] == "好清爽")
XCTAssertTrue(str[-3 ..< 1] == nil)
XCTAssertTrue(str[-3 ... 1] == nil)
XCTAssertTrue(str[0...] == "今天天氣好清爽")
XCTAssertTrue(str[1...] == "天天氣好清爽")
XCTAssertTrue(str[(-2)...] == "清爽")
XCTAssertTrue(str[(-1)...] == "爽")
XCTAssertTrue(str[..<3] == "今天天")
XCTAssertTrue(str[...3] == "今天天氣")
XCTAssertTrue(str[..<(-1)] == "今天天氣好清")
XCTAssertTrue(str[...(-1)] == "今天天氣好清爽")You can install the package using Swift package manager. Add the following lines to your Packages.swift file:
dependencies: [
.package(url: "https://github.com/zonble/HumanString.git"),
],
You can also install the library using CocoaPods, just add pod "HumanString"
to you Podfile.
Swift adopts String.Index since Swift 4. It tends to reminder you that the width of a string is not fixed (SeeStrings in Swift 4). However, it is somehow painful. For example, if you want to extract a prefix from "Hello World", it could be:
let str = "Hello World"
let subString = s[...str.index(str.startIndex, offsetBy: 5)]But wait, somehow you are still using integers, right? The code above could be written as:
let subString = s[str.index(str.startIndex, offsetBy: 0)...str.index(str.startIndex, offsetBy: 5)]I know the Swift team does not like what I am doing here, but somehow I still want to make my life easier.