Question

我有一个结构

 struct Area{    
  var name = String()
  var image = String()}

var area = [Area]()

然后我创建了它的两个实例

let cities = [Area(name:"CityA",image:"CityImgA"), Area(name:"CityB",image:"CityImgB"), Area(name:"CityC",image:"CityImgC") ]
let towns = [Area(name:"TownA",image:"TownImgA"), Area(name:"TownB",image:"TownImgB"), Area(name:"TownC",image:"TownImgC")]

如何找出area是否包含cities或towns并打印出位置，我在用于didSelectItemAt indexPath

的collectionView中尝试了这个

if (self.area == self.cities)
{
  Print ("This is a city")
} 
else
{
   Print ("This is a town")
}

编译因给定错误

而失败

二元运算符＆＃39; ==＆＃39;不能适用于两个[区域]＆＃39;操作数

Answer 1

可能有多种解决方案，简单就是

解决方案1：

写一个扩展名到数组

extension Array where Element: Equatable {
    func contains(array: [Element]) -> Bool {
        for item in array {
            if !self.contains(item) { return false }
        }
        return true
    }
}

最后将您的数组比较为

    if cities.contains(array: areas) {
        print("cities")
    }
    else {
        print("towm")
    }

解决方案2：

第二个解决方案是使用Set转换结构以确认Hashable协议

struct Area : Hashable {

    static func ==(lhs: Area, rhs: Area) -> Bool {
        return lhs.name == rhs.name
    }

    var hashValue: Int {
        return name.hashValue
    }

    var name = String()
    var image = String()
}

最后转换城市和区域以设置和使用isSubset

    let citiesSet = Set(cities)
    let areaSet = Set(areas)

    if areaSet.isSubset(of: citiesSet) {
        print("cities")
    }
    else {
        print("towm")
    }

希望有所帮助

查找选择了哪个struct实例

1 个答案: