编写一个方法，将结构体相应地添加到字典中

func addToSampleDictionary(sample: SampleStruct) {
    sampleDictionary[sample.id] = sample
}

并加以利用

let sample1 = SampleStruct(id: 1, title: "Test text")
addToSampleDictionary(sample: sample1)

在swift中，你可以通过在扩展中添加方法或计算属性来扩展现有类型的功能，这样我们就可以在Dictionary中这样做。在这样做的时候，你也可以通过添加where条件来限制扩展中的代码如何使用。
所以这里是扩展，我们说键必须是Int，值必须是SampleStruct

extension Dictionary where Key == Int, Value == SampleStruct

我们现在可以向这个扩展添加一个函数，并使它特定于SampleStruct
extension Dictionary where Key == Int，Value == SampleStruct { mutating func add（_ object：值）{ self[object.id] = object } }
为了使用这个函数，我们可以这样做

var sampleDictionary: [Int : SampleStruct] = [:]
sampleDictionary.add(SampleStruct(id: 1, title: "Test text"))
sampleDictionary.add(SampleStruct(id: 2, title: "Test text"))

确保字典键和结构id匹配的最简单方法是创建一个辅助函数来添加到字典中：

var sampleDictionary: [Int : SampleStruct] = [:]

func addSampleStruct(_ sampleStruct: SampleStruct) {
    sampleDictionary[sampleStruct.id] = sampleStruct
}

addSampleStruct(SampleStruct(id: 1, title: "Test text"))
addSampleStruct(SampleStruct(id: 2, title: "Test text"))

一种确保字典永远不会被直接访问的方法，可能会添加不匹配的键和id，是创建一个单独的类或结构，其中包含字典和添加/获取等功能：

struct SampleDictionary {
    private var dictionary: [Int: SampleStruct] = [:]
    
    mutating func add(_ sampleStruct: SampleStruct) {
        dictionary[sampleStruct.id] = sampleStruct
    }
    
    func sampleStruct(withId id: Int) -> SampleStruct? {
        dictionary[id]
    }
    
    mutating func removeSampleStruct(withId id: Int) {
        dictionary[id] = nil
    }
    
    var count: Int {
        dictionary.count
    }
}

var sampleDictionary = SampleDictionary()

sampleDictionary.add(SampleStruct(id: 1, title: "Test text"))
sampleDictionary.add(SampleStruct(id: 2, title: "Test text"))

print("count: \(sampleDictionary.count)")

for id in 1...3 {
    if let sampleStruct = sampleDictionary.sampleStruct(withId: id) {
    print("sampleStruct with id \(id) = \(sampleStruct)")
    } else {
        print("there is no sampleStruct with id \(id)")
    }
}