Crash module 4 lesson 2

Hi there, I am following the course, and suddenly the message in previews of CityView class indicate : Cannot preview in this file, GuideBook crashed.
So I downloaded project from web page it works ok, but in my code, not.

I cant upload my project, i don know how. this is the log.

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Translated Report (Full Report Below)
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/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AttributeGraph.framework/AttributeGraph
       0x1b1831000 -        0x1b183dff7 libsystem_pthread.dylib (*) <ba7c01fe-353b-3146-a7c6-f2bb8a0fa842> /usr/lib/system/libsystem_pthread.dylib
       0x1b17db000 -        0x1b1812fe7 libsystem_kernel.dylib (*) <4440d44a-2ab3-3da1-9d8b-42f51e44b45b> /usr/lib/system/libsystem_kernel.dylib
       0x180315000 -        0x1806c3fff com.apple.CoreFoundation (6.9) <132e87d0-14ac-310c-a5e9-3d9c921cc8ea> {"imageOffset":160512,"symbol":"AGGraphGetValue","symbolLocation":216,"imageIndex":36},{"imageOffset":2437760,"imageIndex":4},{"imageOffset":2353712,"imageIndex":4},{"imageOffset":3388532,"imageIndex":4},{"imageOffset":36404,"symbol":"AG::Graph::UpdateStack::update()","symbolLocation":512,"imageIndex":36},{"imageOffset":38196,"symbol":"AG::Graph::update_attribute(AG::data::ptr<AG::Node>, unsigned int)","symbolLocation":428,"imageIndex":36},{"imageOffset":69596,"symbol":"AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, unsigned char&, 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I tryed to put a break point, but i didnt know how.

thanks!!!
Bob

You could upload the project to github or any other online free storage site. Then provide the link to that one folder (kind of like what Chris does for his assets)

Thanks you!! I dont have expertice in github yet, but the important is how detect this kind of error in log or debug. Because when i have long lines of code it isn so easy to look for. Here, I missed a point on “onAppear”, and I think that was de problem.
I will wait for lesson 5 Debug, for see if I can detect this problem, but If you can check it out, I would appreciate.
Bob

//
//  ContentView.swift
//  GuideBook
//
//  Created by Orlando J on 16-07-23.
//

import SwiftUI

struct CityView: View {
    
    @State var cities = [City]()
    var dataService = DataService()
 
    
    var body: some View {
        
        VStack {

            ForEach(cities) { city in
                
                Text(city.name)
            }
            
        }
        .padding()
        onAppear {
            cities = dataService.getData()
        }
    }
}

struct CityView_Previews: PreviewProvider {
    static var previews: some View {
        CityView()
    }
}

onAppear is a view modifier and all view modifier’s are prefixed with a . so the correct code format above is

        .onAppear {
            cities = dataService.getData()
        }