fs_tigre's questions

在下面的代码中，无论我将第二个附加到哪里，.actionSheet我都无法使它们工作。我的理解是，只要他们执着于不同的观点，它就会起作用，但这个理论似乎并不正确。

struct ContentView: View {

        @State private var showFirstActionSheet = false
        @State private var showSecondActionSheet = false
        
        var body: some View {
            VStack{
                VStack{
                    Button("Show Fist Action Sheet"){
                        showFirstActionSheet = true
                    }
                    .actionSheet(isPresented: $showFirstActionSheet) {
                        ActionSheet(title: Text("First Action Sheet"), message:
                                        Text("Some message!"),
                                    buttons: [
                                        .destructive(Text("Cancel")){
                                            
                                        },
                                        .default(Text("Yes")){
                                            doSomething()
                                        },
                                        .cancel()
                                    ])
                    }
                }
            }
            .actionSheet(isPresented: $showSecondActionSheet) {
                ActionSheet(title: Text("Second Action Sheet"), message:
                                Text("Some message!"),
                            buttons: [
                                .destructive(Text("Cancel")){
                                   
                                },
                                .default(Text("Yes")){
                                    
                                },
                                .cancel()
                            ])
            }
        }
        
        func doSomething(){
            showSecondActionSheet = true
        }
    }

我尝试使用两个不同的按钮，它起作用了，但就我而言，我只有一个按钮触发第一个按钮，第二个按钮由第一个 actionSheet 触发。

知道处理这个问题的最佳方法是什么吗？

我试图创建一个对象，如果它不存在于数组中，并删除一个重复的对象。以下代码可以成功确定对象是否已存在以及是否重复，我不确定的是如何捕获方法内 IF 语句内的实际对象，以便能够删除重复if existanceCount == 2{}对象contains(where:)之一。

如何捕获contains(where:)方法内的对象？

我基本上需要访问方法{$0}内部contains(where:)。

func dogCleanup(){
    var existanceCount = 0

    if dogs.contains(where: {$0.name == "Teddy"}){
        existanceCount += 1
        if existanceCount == 2{
            print("Dog exists 2 times, delete it")
            // how can I capture one of the duplicate objects
        }
    }else{
        print("Does NOT exist, add dog...")
    }
}

编辑：添加了dogNames数组。

func dogCleanup(){
    let dogNames = ["Teddy","Browny","Mia"]

    var existanceCount = 0
    for i in 0..<dogNames.count{
        if dogs.contains(where: {$0.name == dogNames[i]}){
            existanceCount += 1
            if existanceCount == 2{
                print("Dog exists 2 times, delete it")
                // how can I capture one of the duplicate objects
            }
        }else{
            print("Does NOT exist, add dog...")
        }
    }
}

编辑2。

这是我所期待的上下文。

实施例1

    let dogs = [Dog(name: "Teddy"), Dog(name: "Browny"),Dog(name: "Mia")] // objects in Core Data
    let dogNames = ["Teddy","Browny","Mia"] // default dog names

    func dogCleanup(){
        // do nothing, both match
    }
    // What I'm expecting after running the dogCleanup
    Teddy,Browny,Mia 

实施例2

    let dogs = [Dog(name: "Teddy"), Dog(name: "Browny")] // objects in Core Data
    let dogNames = ["Teddy","Browny","Mia"]

    func dogCleanup(){
        // add Mia since it doesn't exist in Core Data
    }
    // What I'm expecting after running the dogCleanup
    Teddy, Browny, Mia 

实施例3

    let dogs = [Dog(name: "Teddy"), Dog(name: "Browny"), Dog(name: "Browny")] // objects in Core Data
    let dogNames = ["Teddy","Browny","Mia"] // default dog names

    func dogCleanup(){
        // delete one Browny and add Mia since it doesn't exist in Core Data
    }
    // What I'm expecting after running the dogCleanup
    Teddy, Browny, Mia 

实施例4

    let dogs = [Dog(name: "Teddy"), Dog(name: "Browny"), Dog(name: "Browny"), Dog(name: "Shadow")] // objects in Core Data
    let dogNames = ["Teddy","Browny","Mia"] // default dog names

    func dogCleanup(){
        // delete one Browny, add Mia and leave Shadow
    }
    // What I'm expecting after running the dogCleanup
    Teddy, Browny, Mia, Shadow

如何在NavigationLink标题和箭头/披露指示符之间添加文本，如下左图所示？

SwiftUI 代码：

struct NavigationStackTest: View {
    let fruits = ["Orange", "Apple"]
    var body: some View {
        NavigationStack{
            VStack{
                List(fruits, id:\.self){ fruit in
                    HStack{
                        //Text("Details")
                        NavigationLink(fruit, value: fruit)
                        Text("Details")
                    }
                }
                .navigationDestination(for: String.self) { item in
                    Text(verbatim: item)
                }
            }
        }
    }
}

在将图像保存到 Core Data 之前调整图像大小的通常过程是什么？

我希望能够将图像大小调整为 75px75p，然后再将其保存到 Core Data 以最小化其大小。图像可以直接来自照片库或相机。我有一种感觉，我目前保存它的方式，它保存了一个巨大的文件大小，而实际上我只需要一个缩略图（75x75）。

这是我目前保存它的方式。

核心数据对象： Item

属性： image: Binary Data

// image is passed to the addItem function directly from an Image Picker
func addItem(name:String, image:UIImage?){
    if let image = image {
        imageData = image.jpegData(compressionQuality: 0.1)!
    }else{
        imageData = nil
    }
    item.name = name
    item.image = imageData
    self.manager.save()
}

任何建议将不胜感激。