Swift:从字符串中提取子字符串

Question

我有一个字符串，它可以是以下之一:

tempString = "What? The ID: 54673 Over there"
tempString = "Jump... ID: 4561E how high"

基本上，我想从字符串中检索五个字符的 ID:。对于大多数语言，我可以通过查找 ID: 来实现这一点，向其添加 4 以到达 ID: 的开头，然后获取接下来的五个字符。
例如，在 Excel 中:

=MID("Jump... ID: 4561E how high",FIND("ID:","Jump... ID: 4561E how high")+4, 5)

将 = 4561E。
我们如何用 Swift 做到这一点？

Answer 1

在“ID:”之后从 [0-9] 或 [A-F] 中查找前 5 个字符的正则表达式方法(仅当您不能使用 A-Z 时才使用十六进制字母)。

if let range = string.range(of: "(?<=ID: )[0-9A-F]{5}", options: .regularExpression) {
    let id = string[range]  // 
    // if you need a String instead of a substring
    let stringID = String(string[range])
}

编辑/更新:
看看你的答案，看起来要求与你的原始帖子完全不同，无论如何找到一个 IF 复合 8 个十六进制字符后跟连字符然后 4 个六进制字符后跟连字符(3 次)比 12 个十六进制字符你可以使用以下正则表达式 "([0-9a-f]{8}-)([0-9a-f]{4}-){3}([0-9a-f]{12})" :

let dataString = """
{
  "@odata.context": "$metadata#GeoFences(Points())/$entity",
  "ID": "2b2a2abc-5962-4290-92b4-773025ffd50b",
  "Points": {
    "POINT_TYPE": "F",
    "POINT_NUM": 0,
    "LATITUDE": 32.92197686725423,
    "LONGITUDE": -117.04306932263532,
    "parent_ID": "2b2a2abc-5962-4290-92b4-773025ffd50b"
  },
  "GEOFENCE_NAME": "New Fence",
  "GEOFENCE_TYPE": "O",
  "PRIVACY": "X",
  "CENTER_LAT": 32.92043316309709,
  "CENTER_LONG": -117.04286922250975,
  "ZOOM_LAT": 0.006238797350533787,
  "ZOOM_LONG": 0.005345531926053582,
  "PATH_TOLERANCE": 5,
  "ENTRANCE_TOLERANCE": 5
}
"""

if let range = dataString.range(of: "([0-9a-f]{8}-)([0-9a-f]{4}-){3}([0-9a-f]{12})", options: .regularExpression) {
    let id = dataString[range]  // 4561E
    print("ID:", id)
    // if you need a String instead of a substring
    let stringID = String(dataString[range])
    print("stringID:", stringID)
}

这将打印

ID: 2b2a2abc-5962-4290-92b4-773025ffd50b

stringID: 2b2a2abc-5962-4290-92b4-773025ffd50b

请注意，您的代码将导致 "2b2a2abc-5962-4290-92b4-773025ffd50
编辑/更新2:
考虑到您的字符串是 JSON，您可以简单地解码您的字符串 ID:

struct Root: Codable {
    let id: String
    enum CodingKeys: String, CodingKey {
        case id = "ID"
    }
}
do {
    let id = try JSONDecoder().decode(Root.self, from: Data(dataString.utf8)).id
    print(id)  // "2b2a2abc-5962-4290-92b4-773025ffd50b"
} catch {
    print(error)
}

如果您需要解码所有数据:

struct Root: Codable {
    let odataContext, id: String
    let points: Points
    let geofenceName, geofenceType, privacy: String
    let centerLat, centerLong, zoomLat, zoomLong: Double
    let pathTolerance, entranceTolerance: Int

    enum CodingKeys: String, CodingKey {
        case odataContext = "@odata.context", id = "ID", points = "Points", geofenceName = "GEOFENCE_NAME", geofenceType = "GEOFENCE_TYPE", privacy = "PRIVACY", centerLat = "CENTER_LAT", centerLong = "CENTER_LONG", zoomLat = "ZOOM_LAT", zoomLong = "ZOOM_LONG", pathTolerance = "PATH_TOLERANCE", entranceTolerance = "ENTRANCE_TOLERANCE"
    }
}

struct Points: Codable {
    let pointType: String
    let pointNum: Int
    let latitude, longitude: Double
    let parentID: String

    enum CodingKeys: String, CodingKey {
        case pointType = "POINT_TYPE", pointNum = "POINT_NUM", latitude = "LATITUDE", longitude = "LONGITUDE", parentID = "parent_ID"
    }
}

do {
    let root = try JSONDecoder().decode(Root.self, from: Data(dataString.utf8))
    print("ID:", root.id)  // ID: 2b2a2abc-5962-4290-92b4-773025ffd50b
    print("Root:", root)   // Root: Root(odataContext: "$metadata#GeoFences(Points())/$entity", id: "2b2a2abc-5962-4290-92b4-773025ffd50b", points: __lldb_expr_111.Points(pointType: "F", pointNum: 0, latitude: 32.92197686725423, longitude: -117.04306932263532, parentID: "2b2a2abc-5962-4290-92b4-773025ffd50b"), geofenceName: "New Fence", geofenceType: "O", privacy: "X", centerLat: 32.92043316309709, centerLong: -117.04286922250975, zoomLat: 0.0062387973505337885, zoomLong: 0.005345531926053582, pathTolerance: 5, entranceTolerance: 5)
} catch {
    print(error)
}