Characteristic.value from Swift in Swift

Question

BTデバイスから文字列を読み込んで文字列に変換しようとしています。

<CBCharacteristic: 0x1700a2e80, UUID = 2A9D, properties = 0x20, value = <02ac08e1 07010a14 0029>, notifying = YES> 

は、例に基づいて、私は私が

let u16 = (characteristic.value! as NSData).bytes.bindMemory(to: Int.self, capacity: characteristic.value!.count).pointee 

をしたオンライン見つかりましたが、私のU16はcharacteristic.valueが含まれているにもかかわらず、nullである

(lldb) dp characteristic.value! as NSData 
<02ac08e1 07010a14 0029> 

誰もが正しい方向に私を指すことができますか？

Answer 1

これは簡単ではありません。

Weight Measurement

あなたはこのような何かを書く必要があります。

let data = Data([0x02,0xac,0x08,0xe1,0x07,0x01,0x0a,0x14,0x00,0x29]) 

struct DataReader { 
    var data: Data 
    var offset: Int = 0 

    mutating func read() -> UInt8 { 
     let result = data[offset] 
     offset += MemoryLayout<UInt8>.size 
     return result 
    } 
    mutating func read() -> UInt16 { 
     let subdata = data.subdata(in: offset..<offset+MemoryLayout<UInt16>.size) 
     let result: UInt16 = subdata.withUnsafeBytes {(bytes: UnsafePointer<UInt16>) in 
      bytes.pointee.littleEndian 
     } 
     offset += MemoryLayout<UInt16>.size 
     return result 
    } 
} 

typealias BLEUserID = UInt8 

struct BLEDateTime { 
    var year: UInt16 
    var month: UInt8 
    var day: UInt8 
    var hours: UInt8 
    var minutes: UInt8 
    var seconds: UInt8 
} 
extension DataReader { 
    mutating func read() -> BLEDateTime { 
     let year: UInt16 = read() 
     let month: UInt8 = read() 
     let day: UInt8 = read() 
     let hours: UInt8 = read() 
     let minutes: UInt8 = read() 
     let seconds: UInt8 = read() 
     return BLEDateTime(year: year, month: month, day: day, hours: hours, minutes: minutes, seconds: seconds) 
    } 
} 
struct WeightMeasurement: CustomStringConvertible { 
    struct Flags: OptionSet { 
     var rawValue: UInt8 
     init(rawValue: UInt8) { 
      self.rawValue = rawValue 
     } 
     static let measurementImperial = Flags(rawValue: 1<<0) 
     static let timeStampPresent = Flags(rawValue: 1<<1) 
     static let userIDPresent = Flags(rawValue: 1<<2) 
     static let bmiAndHeightPresent = Flags(rawValue: 1<<3) 
    } 
    var isMeasuremntImperial: Bool 
    var weight: Decimal 
    var timeStamp: BLEDateTime? 
    var userID: BLEUserID? 
    var bmi: Decimal? 
    var height: Decimal? 

    var description: String { 
     return weight.description 
    } 
} 
extension DataReader { 
    mutating func read() -> WeightMeasurement { 
     let flags = WeightMeasurement.Flags(rawValue: read()) 
     let isMeasuremntImperial = flags.contains(.measurementImperial) 
     let weight: Decimal 
     if isMeasuremntImperial { 
      weight = Decimal(read() as UInt16) * Decimal(string: "0.01")! 
     } else { 
      //SI 
      weight = Decimal(read() as UInt16) * Decimal(string: "0.005")! 
     } 
     var timeStamp: BLEDateTime? 
     if flags.contains(.timeStampPresent) { 
      timeStamp = read() 
     } 
     var userID: BLEUserID? 
     if flags.contains(.userIDPresent) { 
      userID = read() 
     } 
     var bmi: Decimal? 
     var height: Decimal? 
     if flags.contains(.bmiAndHeightPresent) { 
      bmi = Decimal(read() as UInt16) * Decimal(string: "0.1")! 
      if isMeasuremntImperial { 
       height = Decimal(read() as UInt16) * Decimal(string: "0.1")! 
      } else { 
       //SI 
       height = Decimal(read() as UInt16) * Decimal(string: "0.001")! 
      } 
     } 
     return WeightMeasurement(isMeasuremntImperial: isMeasuremntImperial, weight: weight, timeStamp: timeStamp, userID: userID, bmi: bmi, height: height) 
    } 
} 

var reader = DataReader(data: data, offset: 0) 
let weightMeasurement: WeightMeasurement = reader.read() 
print(weightMeasurement) //->11.1 
print(weightMeasurement.timeStamp!) //->BLEDateTime(year: 2017, month: 1, day: 10, hours: 20, minutes: 0, seconds: 41) 

（申し訳ありませんが、完全にテストされ、あなたは、いくつかの変更が必要な場合がありません。）