第一期

GeometryReader使里面的所有东西都缩小到它的最小尺寸。
将.border(Color.orange)添加到ZStack，您将看到类似于下面的内容。

您可以使用.frame(maxWidth: .infinity, maxHeight: .infinity)来拉伸ZStack以占用所有可用空间。

第二期

position与offset的比较。
offset通常从中心开始，然后按指定的量offset。
position更像是origin。
将此视图的中心定位在其父级坐标空间中的指定坐标处。

第3期

调整中心位置与原点使用的左上角（0，0）。

第4期

ZStack需要在X轴上翻转。
下面是完整的代码

import SwiftUI
import Vision
import CoreML
@MainActor
class Detection: ObservableObject {
    //Moved file to assets
    //let imgURL = URL(string: "https://i.imgur.com/EqsxxTc.jpg")! // Xcode preview generates this: https://i.imgur.com/6IPNQ8b.png
    let imageName: String = "EqsxxTc"
    @Published var objects: [VNRecognizedObjectObservation] = []
    
    func getModel() throws -> VNCoreMLModel {
        //Used model directly instead of loading from URL
        let model = try YOLOv3Tiny(configuration: .init()).model
        
        let mlModel = try VNCoreMLModel(for: model)
        
        return mlModel
    }
    
    func detect() async throws {
        let model = try getModel()
        
        guard let tiff = NSImage(named: imageName)?.tiffRepresentation else {
            // YOLOv3Tiny: https://ml-assets.apple.com/coreml/models/Image/ObjectDetection/YOLOv3Tiny/YOLOv3Tiny.mlmodel
            //fatalError("Either YOLOv3Tiny.mlmodel is not in project bundle, or image failed to load.")
            throw AppError.unableToLoadImage
        }
        //Completion handlers are not compatible with async/await you have to convert to a continuation.
        self.objects = try await withCheckedThrowingContinuation { (cont: CheckedContinuation<[VNRecognizedObjectObservation], Error>) in
            
            let request = VNCoreMLRequest(model: model) { (request, error) in
                if let error = error{
                    cont.resume(throwing: error)
                }else{
                    cont.resume(returning: (request.results as? [VNRecognizedObjectObservation]) ?? [])
                }
            }
            do{
                try VNImageRequestHandler(data: tiff).perform([request])
            }catch{
                cont.resume(throwing: error)
            }
        }
    }
    
    func deNormalize(_ rect: CGRect, _ geometry: GeometryProxy) -> CGRect {
        return VNImageRectForNormalizedRect(rect, Int(geometry.size.width), Int(geometry.size.height))
    }
}

struct ContentView: View {
    @StateObject var detection = Detection()
    
    var body: some View {
        Image(detection.imageName)
            .resizable()
            .scaledToFit()
            .overlay {
                GeometryReader { geometry in
                    ZStack {
                        ForEach(detection.objects, id: \.uuid) { object in
                            let rect = detection.deNormalize(object.boundingBox, geometry)
                            Rectangle()
                                .stroke(lineWidth: 2)
                                .foregroundColor(.red)
                                .frame(width: rect.width, height: rect.height)
                            //Changed to position
                            //Adjusting for center vs leading origin
                                .position(x: rect.origin.x + rect.width/2, y: rect.origin.y + rect.height/2)
                        }
                    }
                    //Geometry reader makes the view shrink to its smallest size
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
                    //Flip upside down
                    .rotation3DEffect(.degrees(180), axis: (x: 1, y: 0, z: 0))
                    
                }.border(Color.orange)
            }
        
            .task {
                do{
                    try await self.detection.detect()
                }catch{
                    //Always throw errors to the View so you can tell the user somehow. You don't want crashes or to leave the user waiting for something that has failed.
                    print(error)
                }
            }
    }
}
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

enum AppError: LocalizedError{
    case cannotFindFile
    case unableToLoadImage
}

我还改变了一些其他的东西，你可以注意到，在代码中有注解。

好吧，所以经过长时间的故障排除，我终于设法使它正确工作（同时仍然不了解问题的原因）...
问题出在这一部分：

GeometryReader { geometry in
    ZStack {
        ForEach(detection.objects, id: \.uuid) { object in
            let rect = detection.deNormalize(object.boundingBox, geometry)
            Rectangle()
                .stroke(lineWidth: 2)
                .foregroundColor(.red)
                .frame(width: rect.width, height: rect.height)
                .offset(x: rect.origin.x, y: rect.origin.y)
        }
    }
}

我假设因为许多Rectangle()会重叠，所以我需要一个ZStack()来将它们相互覆盖，结果证明这是错误的，显然当使用.offset()时，它们可以重叠而没有任何问题，所以删除ZStack()完全解决了问题：

GeometryReader { geometry in
    ForEach(detection.objects, id: \.uuid) { object in
        let rect = detection.deNormalize(object.boundingBox, geometry)
        Rectangle()
            .stroke(lineWidth: 2)
            .foregroundColor(.red)
            .frame(width: rect.width, height: rect.height)
            .offset(x: rect.origin.x, y: rect.origin.y)
    }
}

我仍然不明白的是，为什么将ZStack()移到GeometryReader()之外也能解决问题，以及为什么有些框的位置正确，而有些则不正确！

ZStack {
    GeometryReader { geometry in
        ForEach(detection.objects, id: \.uuid) { object in
            let rect = detection.deNormalize(object.boundingBox, geometry)
            Rectangle()
                .stroke(lineWidth: 2)
                .foregroundColor(.red)
                .frame(width: rect.width, height: rect.height)
                .offset(x: rect.origin.x, y: rect.origin.y)
        }
    }
}