HotProspects

Project description.

Technologies used:

SwiftUI (@EnvironmentObject, TabView)

Day 79

@EnvironmentObject

Environment objects use the same ObservableObject protocol as @ObservedObject.

struct ContentView: View {
    let user = User()

    var body: some View {
        VStack {
            EditView()
            DisplayView()
        }.environmentObject(user)
    }
} 

struct EditView: View {
    @EnvironmentObject var user: User

    var body: some View {
        TextField("Name", text: $user.name)
    }
}

That @EnvironmentObject property wrapper will automatically look for a User instance in the environment, and place whatever it finds into the user property. If it can’t find a User in the environment the app will just crash.

TabView & the tabItem() modifier

TabView {
    Text("Tab 1")
        .tabItem {
            Image(systemName: "star")
            Text("One")
        }

    Text("Tab 2")
        .tabItem {
            Image(systemName: "star.fill")
            Text("Two")
        }
}

Day 80

Result type

func fetchData(from urlString: String, completion: @escaping (Result<String, NetworkError>) -> Void) {
    // check the URL is OK, otherwise return with a failure
    guard let url = URL(string: urlString) else {
        completion(.failure(.badURL))
        return
    }

    URLSession.shared.dataTask(with: url) { data, response, error in
        // the task has completed – push our work back to the main thread
        DispatchQueue.main.async {
            if let data = data {
                // success: convert the data to a string and send it back
                let stringData = String(decoding: data, as: UTF8.self)
                completion(.success(stringData))
            } else if error != nil {
                // any sort of network failure
                completion(.failure(.requestFailed))
            } else {
                // this ought not to be possible, yet here we are
                completion(.failure(.unknown))
            }
        }
    }.resume()
}

And then just switch on the Result:

Text("Hello, World!")
    .onAppear {
        self.fetchData(from: "https://www.apple.com") { result in
            switch result {
            case .success(let str):
                print(str)
            case .failure(let error):
                switch error {
                case .badURL:
                    print("Bad URL")
                case .requestFailed:
                    print("Bad URL")
                case .unknown:
                    print("Unknown error")
                }
            }
        }
    }

Manually publishing ObservableObject changes

class DelayedUpdater: ObservableObject {

    //instead of @Published
    var value = 0 {
        willSet {
            objectWillChange.send()
        }
    } 


}

Controlling image interpolation in SwiftUI

To see the stretched image retain its pixellated look:

Image("example")
    .interpolation(.none)    
    .resizable()
    .scaledToFit()
    .frame(maxHeight: .infinity)
    .background(Color.black)
    .edgesIgnoringSafeArea(.all)

Day 81

Context Menus

Just add a .contextMenu {} modifier to a View and provide Buttons with a Text and an Image.

Local Notifications

import UserNotifications

Swift Package Manager

Day 82

Building our tab bar
Sharing data across tabs using @EnvironmentObject
Dynamically filtering a SwiftUI List

Day 83

Generating and scaling up a QR code
Scanning QR codes with SwiftUI
Adding options with a context menu

Day 84

Saving and loading data with UserDefaults
Posting notifications to the lock screen

Day 85 Challenges

Add an icon to the “Everyone” screen showing whether a prospect was contacted or not.
Use JSON and the documents directory for saving and loading our user data.
Use an action sheet to customize the way users are sorted in each screen – by name or by most recent.

leontedev/HotProspects