ios - 如何从 UILabel 中删除可选文本

Question

我正在尝试删除 Optional我的文字 UILabel当我运行应用程序时。但是，我已经尝试了很多方法并且 Optional坚持。

重要的是要说我从 JSON 中获得了这些值，所以我创建了一个 Struct解码所有这些数据。属性(property)ibu是唯一拥有 Optional 的写了，但如果我删除 ?我在 JSONDecoder 上出错那是说:

Swift.DecodingError.Context(codingPath: [_JSONKey(stringValue: "Index 23", intValue: 23), CodingKeys(stringValue: "ibu", intValue: nil)], debugDescription: "Expected Double value but found null instead.", underlyingError: nil))

我该如何解决？

应用图片:

模型文件夹:

  struct Cerveja:Decodable{
        let name:String
        let image_url:String
        let description:String
        let tagline:String
        let abv:Double
        let ibu:Double? //This one that I got the "Optional" written in the UILabel
                        //If I remove the "?" I got the error below
    }

查看文件夹 - 详细信息屏幕:

var item:Cerveja?

override func viewDidLoad() {
    super.viewDidLoad()

    labelName.text = item?.name
    labelDescricao.text = item?.description
    labelAmargor.text = "\(String(describing: item!.ibu))" 
    labelTeorAlc.text = "\(item!.abv)"

    let resource = ImageResource(downloadURL: URL(string: "\(item?.image_url ?? "")")!, cacheKey: item?.image_url)
    imageDetail.kf.setImage(with: resource)
}

网络文件夹:

func getApiData(completion: @escaping ([Cerveja]) -> ()){
    guard let urlString = URL(string: "https://api.punkapi.com/v2/beers") else {
        print("URL Error")
        return
    }
    Alamofire.request(urlString).responseJSON { response in

        if response.data == response.data{
            do{
                let decoder = try JSONDecoder().decode([Cerveja].self, from: response.data!)

                completion(decoder)
            }catch{
        print(error)
            }
        }else{print("API Response is Empty")}

        }
}

JSON:

[
  {
    "id": 1,
    "name": "Buzz",
    "tagline": "A Real Bitter Experience.",
    "first_brewed": "09\/2007",
    "description": "A light, crisp and bitter IPA brewed with English and American hops. A small batch brewed only once.",
    "image_url": "https:\/\/images.punkapi.com\/v2\/keg.png",
    "abv": 4.5,
    "ibu": 60,
    "target_fg": 1010,
    "target_og": 1044,
    "ebc": 20,
    "srm": 10,
    "ph": 4.4,
    "attenuation_level": 75,
    "volume": {
      "value": 20,
      "unit": "liters"
    },
    "boil_volume": {
      "value": 25,
      "unit": "liters"
    },
    "method": {
      "mash_temp": [
        {
          "temp": {
            "value": 64,
            "unit": "celsius"
          },
          "duration": 75
        }
      ],
      "fermentation": {
        "temp": {
          "value": 19,
          "unit": "celsius"
        }
      },
      "twist": null
    },
    "ingredients": {
      "malt": [
        {
          "name": "Maris Otter Extra Pale",
          "amount": {
            "value": 3.3,
            "unit": "kilograms"
          }
        },
        {
          "name": "Caramalt",
          "amount": {
            "value": 0.2,
            "unit": "kilograms"
          }
        },
        {
          "name": "Munich",
          "amount": {
            "value": 0.4,
            "unit": "kilograms"
          }
        }
      ],
      "hops": [
        {
          "name": "Fuggles",
          "amount": {
            "value": 25,
            "unit": "grams"
          },
          "add": "start",
          "attribute": "bitter"
        },
        {
          "name": "First Gold",
          "amount": {
            "value": 25,
            "unit": "grams"
          },
          "add": "start",
          "attribute": "bitter"
        },
        {
          "name": "Fuggles",
          "amount": {
            "value": 37.5,
            "unit": "grams"
          },
          "add": "middle",
          "attribute": "flavour"
        },
        {
          "name": "First Gold",
          "amount": {
            "value": 37.5,
            "unit": "grams"
          },
          "add": "middle",
          "attribute": "flavour"
        },
        {
          "name": "Cascade",
          "amount": {
            "value": 37.5,
            "unit": "grams"
          },
          "add": "end",
          "attribute": "flavour"
        }
      ],
      "yeast": "Wyeast 1056 - American Ale\u2122"
    },
    "food_pairing": [
      "Spicy chicken tikka masala",
      "Grilled chicken quesadilla",
      "Caramel toffee cake"
    ],
    "brewers_tips": "The earthy and floral aromas from the hops can be overpowering. Drop a little Cascade in at the end of the boil to lift the profile with a bit of citrus.",
    "contributed_by": "Sam Mason <samjbmason>"
  },
  {
    "id": 2,
    "name": "Trashy Blonde",
    "tagline": "You Know You Shouldn't",
    "first_brewed": "04\/2008",
    "description": "A titillating, neurotic, peroxide punk of a Pale Ale. Combining attitude, style, substance, and a little bit of low self esteem for good measure; what would your mother say? The seductive lure of the sassy passion fruit hop proves too much to resist. All that is even before we get onto the fact that there are no additives, preservatives, pasteurization or strings attached. All wrapped up with the customary BrewDog bite and imaginative twist.",
    "image_url": "https:\/\/images.punkapi.com\/v2\/2.png",
    "abv": 4.1,
    "ibu": 41.5,
    "target_fg": 1010,
    "target_og": 1041.7,
    "ebc": 15,
    "srm": 15,
    "ph": 4.4,
    "attenuation_level": 76,
    "volume": {
      "value": 20,
      "unit": "liters"
    },
    "boil_volume": {
      "value": 25,
      "unit": "liters"
    },
    "method": {
      "mash_temp": [
        {
          "temp": {
            "value": 69,
            "unit": "celsius"
          },
          "duration": null
        }
      ],
      "fermentation": {
        "temp": {
          "value": 18,
          "unit": "celsius"
        }
      },
      "twist": null
    },
    "ingredients": {
      "malt": [
        {
          "name": "Maris Otter Extra Pale",
          "amount": {
            "value": 3.25,
            "unit": "kilograms"
          }
        },
        {
          "name": "Caramalt",
          "amount": {
            "value": 0.2,
            "unit": "kilograms"
          }
        },
        {
          "name": "Munich",
          "amount": {
            "value": 0.4,
            "unit": "kilograms"
          }
        }
      ],
      "hops": [
        {
          "name": "Amarillo",
          "amount": {
            "value": 13.8,
            "unit": "grams"
          },
          "add": "start",
          "attribute": "bitter"
        },
        {
          "name": "Simcoe",
          "amount": {
            "value": 13.8,
            "unit": "grams"
          },
          "add": "start",
          "attribute": "bitter"
        },
        {
          "name": "Amarillo",
          "amount": {
            "value": 26.3,
            "unit": "grams"
          },
          "add": "end",
          "attribute": "flavour"
        },
        {
          "name": "Motueka",
          "amount": {
            "value": 18.8,
            "unit": "grams"
          },
          "add": "end",
          "attribute": "flavour"
        }
      ],
      "yeast": "Wyeast 1056 - American Ale\u2122"
    },
    "food_pairing": [
      "Fresh crab with lemon",
      "Garlic butter dipping sauce",
      "Goats cheese salad",
      "Creamy lemon bar doused in powdered sugar"
    ],
    "brewers_tips": "Be careful not to collect too much wort from the mash. Once the sugars are all washed out there are some very unpleasant grainy tasting compounds that can be extracted into the wort.",
    "contributed_by": "Sam Mason <samjbmason>"
  },
  {
    "id": 3,
    "name": "Berliner Weisse With Yuzu - B-Sides",
    "tagline": "Japanese Citrus Berliner Weisse.",
    "first_brewed": "11\/2015",
    "description": "Japanese citrus fruit intensifies the sour nature of this German classic.",
    "image_url": "https:\/\/images.punkapi.com\/v2\/keg.png",
    "abv": 4.2,
    "ibu": 8,
    "target_fg": 1007,
    "target_og": 1040,
    "ebc": 8,
    "srm": 4,
    "ph": 3.2,
    "attenuation_level": 83,
    "volume": {
      "value": 20,
      "unit": "liters"
    },
    "boil_volume": {
      "value": 25,
      "unit": "liters"
    },
    "method": {
      "mash_temp": [
        {
          "temp": {
            "value": 60,
            "unit": "celsius"
          },
          "duration": 10
        },
        {
          "temp": {
            "value": 65,
            "unit": "celsius"
          },
          "duration": 30
        },
        {
          "temp": {
            "value": 72,
            "unit": "celsius"
          },
          "duration": 10
        },
        {
          "temp": {
            "value": 78,
            "unit": "celsius"
          },
          "duration": 5
        }
      ],
      "fermentation": {
        "temp": {
          "value": 21,
          "unit": "celsius"
        }
      },
      "twist": "Soured naturally using the kettle souring technique, Yuzu fruit: 50g at middle, Yuzu juice: 200ml at FV"
    },
    "ingredients": {
      "malt": [
        {
          "name": "Propino Pale Malt",
          "amount": {
            "value": 1.63,
            "unit": "kilograms"
          }
        },
        {
          "name": "Wheat Malt",
          "amount": {
            "value": 1.63,
            "unit": "kilograms"
          }
        },
        {
          "name": "Propino Pale Malt for kettle 0.03kg souring",
          "amount": {
            "value": 0.03,
            "unit": "kilograms"
          }
        },
        {
          "name": "Acidulated Malt for kettle souring",
          "amount": {
            "value": 0.03,
            "unit": "kilograms"
          }
        }
      ],
      "hops": [
        {
          "name": "Bramling Cross",
          "amount": {
            "value": 10,
            "unit": "grams"
          },
          "add": "middle",
          "attribute": "bitter"
        }
      ],
      "yeast": "Wyeast 1056 - American Ale\u2122"
    }

Answer 1

使用optional binding为了避免这个问题

使用

if let ibu = item?.ibu {
  labelAmargor.text = "\(String(describing: ibu))" 
} 

代替

labelAmargor.text = "\(String(describing: item!.ibu))"