[Swift]エラー処理

ガイドルート-iOSプログラミングのSwiftベース

1.エラー表示

enum LocationManagerError: Error {
  case authorizationDenied
  case coordinateError
}

2.放出関数のエラー

func requestLocation(completion: @escaping (_ coordinate: CLLocationCoordinate2D) -> ()) throws {
  locationManager.delegate = self
  guard CLLocationManager.locationServicesEnabled() else {
    throw LocationManagerError.authorizationDenied
  }
  locationManager.requestWhenInUseAuthorization()
  locationManager.requestLocation()
  locationManager.desiredAccuracy = kCLLocationAccuracyBest
  guard let coordinate = locationManager.location?.coordinate else {
    throw LocationManagerError.coordinateError
  }
  completion(coordinate)
}

3.エラー処理

do-catch

  do {
    try locationManger.requestLocation(){ coordinate in
      currentLocationViewModel.convertToAddress(latitude: coordinate.latitude, longtitude: coordinate.longitude, completion: {
        let locationName = $0
        fineDustViewModel.loadFineDust(latitude: coordinate.latitude, longtitude: coordinate.longitude, completion: {
          let entry = simpleEntry(currentDate: currentDate,
                                  locationName: locationName,
                                  fineDust:  $0.fineDust,
                                  ultraFineDust: $0.ultraFineDust,
                                  configuration: configuration)
          let refreshDate = Calendar.current.date(byAdding: .minute, value: 30, to: currentDate)!
          let timeline = Timeline(entries: [entry], policy: .after(refreshDate))
          completion(timeline)
        })
      })
    }
  } catch {
    let entry = simpleEntry(currentDate: currentDate,
                            locationName: "오류",
                            fineDust: fineDustViewModel.fineDust("-"),
                            ultraFineDust: fineDustViewModel.ultraFineDust("-"),
                            configuration: configuration)
    let refreshDate = Calendar.current.date(byAdding: .second, value: 10, to: currentDate)!
    let timeline = Timeline(entries: [entry], policy: .after(refreshDate))
    completion(timeline)
  }
}

try?

try!

SWIFT 3.0のthrowsとrethrowsについて...

rethrows

defer构文の理解

defer

func test() {
    defer {
        print("실행 2")
    }

    print("실행 1")
}

// 실행 1
// 실행 2