SwiftUI Gists

SwiftUI Components & Extension that saves iOSDev time.
### UIKit is **EVENT-Driven** framework - We could reference each view in the hierarchy, update its appearance when the view is loaded or as a reaction on an event.
### SwiftUI is **Declarative, State Driven** framework - We cannot reference any view in the hierarchy, neither can we directly mutate a view as a reaction to an event. 
Instead, we mutate the state bound to the view. Delegates, target-actions, responder chain, KVO .. replaced with Closures & bindings.

Corner Radius in specific corner

.background(Rectangle().cornerRadius(40.0, corners: [.topLeft, .topRight]).foregroundColor(Color(0xF4F5FC)))

extension View {
    func cornerRadius(_ radius: CGFloat, corners: UIRectCorner) -> some View {
        clipShape( RoundedCorner(radius: radius, corners: corners) )
    }
}

struct RoundedCorner: Shape {

    var radius: CGFloat = .infinity
    var corners: UIRectCorner = .allCorners

    func path(in rect: CGRect) -> Path {
        let path = UIBezierPath(roundedRect: rect, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
        return Path(path.cgPath)
    }
}

What SwiftUI Transitions Are Available ?
There are 5 transitions available in SwiftUI:

1. Slide - slide in the view from the leading side and remove it towards the trailing side.
2. Move - slide in from the direction specified and remove it from the same direction.
3. Opacity - fade in the view when inserted and fade out the view when removed.
4. Scale - insert the view FROM the scale specified and reverse the effect when removed.
5. Offset - like the move transition by you can set your own x and y coordinate.

Choices for applying an animation?

1. Apply an animation directly to the view.
2. Apply an animation to the parent view.
3. Use an explicit animation (withAnimation closure) around the variable change that controls when the view is inserted/removed.

⚠️ As of this writing, the opacity and scale only work with explicit animations (withAnimation).

Creating a List with Navigation Link
Note the hierarchy : NavigationView >> List >> NavigationLink

        NavigationView {
            List(1...10, id: \.self) { index in
                
                if index == 1 {
                    //do something for row = 1
                }
                else{
                    NavigationLink(
                        destination: Text("Item #\(index) Details"),
                        label: {
                            Text("Item #\(index)")
                                .font(.system(size: 20, weight: .bold, design: .rounded))
                        })
                }
            
            }
            
            .navigationTitle("Latest News")
        }

Tabbar/ TabView creation - VStack as parent.

       VStack {
           
           TabView {
             
               
               Text("Video Tab")
                   .font(.system(size: 30, weight: .bold, design: .rounded))
                   .tabItem {
                       Image(systemName: "video.circle.fill")
                       Text("Live")
                   }
               
        
                
               Text("Profile Tab")
                   .font(.system(size: 30, weight: .bold, design: .rounded))
                   .tabItem {
                       Image(systemName: "person.crop.circle")
                       Text("Profile")
                   }
           }
           .accentColor(.red)
           .onAppear() {
               UITabBar.appearance().barTintColor = .white
           }
       }

Tint color and selection/highlight color of tab changed.

Click/Tap/Select/Touch event to view:

    @State private var isPresented = false

<your view>.gesture(DragGesture(minimumDistance: 0)
                                                        .onChanged { value in
                                                            if isPresented {
                                                                print("Touch down")
                                                            }
                                                            isPresented = false
                                                        }
                                                        .onEnded { value in
                                                            print("Touch up")
                                                            isPresented = true
                                                        }
                                                )
                                            

.navigationBarHidden(true) is not constructed for NavigationView instead, it should be it's child.

Return a view from a function - that checks some conditions.
PS: return types : some View vs AnyView vs View
Ref: https://stackoverflow.com/questions/62895948/how-to-return-a-view-type-from-a-function-in-swift-ui

@ViewBuilder func WidgetDetail(wOption: WidgetOptions) -> some View {
        switch wOption.id {
        case 0:
            CountryPicker()
        default:
            Text("Widget Not implemented")
        }
    }

Present view Modally (fullscreen) [ for iOS 14.0+]

         @State var isQuizPlayPresented = false
            
            Button(action: {
                  isQuizPlayPresented.toggle()
              }) {
                  Text("Get Started")
              }
              .padding()
              .fullScreenCover(isPresented: $isQuizPlayPresented, onDismiss: nil, content: QuizPlayView.init)

Dismiss a presented view (modally)

    @Environment(\.presentationMode) private var presentationMode // define
     self.presentationMode.wrappedValue.dismiss() // In button action

Advanced:

            .fullScreenCover(isPresented: $isResultView,
                             onDismiss: {
                self.presentationMode.wrappedValue.dismiss() // Dismisses current view along with Child view dismissed
            }, content: {
                QuizResultView(totalScore: 10) // Pass custom parameter to child view
            })

Make the width of element fill till parent width

        VStack(alignment: .center) {
          Rectangle()
            .frame(height: 0.0) // -------- note this 
           Text("SHOW DETAILS")
        }
        .background(.yellow)
        

Basic Rail :

struct QuizRail: View {
  
  var body: some View {
    ScrollView(.horizontal) {
      HStack(spacing: 16) {
        ForEach((1...10), id: \.self) {_ in
          Rectangle()
            .frame(width: 150, height: 200)
            .cornerRadius(8)
        }
      }
      .padding(.horizontal, 16)
    }
  }
}

List without separator (from iOS 15.0+)

          List {
            ForEach(items, id: \.self) { item in
              Text("item here")
                .listRowSeparator(.hidden)

            }
          }
          .listStyle(.plain)

☢️ A workaround calculated the height of ScrollView

  @State var heightCalculated = 0.0

  var body: some View {

    ScrollView {
      ForEach(0..<10) { i in
        Text("\(i)")
      }
      .background(
        GeometryReader { proxy in
          Color.clear.onAppear { 
            heightCalculated = proxy.size.height
            debugPrint(proxy.size.height)
          }
        }
      )

    }
    .frame(height: heightCalculated)
  }

To make Content view as parameter. A better way to build Generic views.

struct ContainerView<Content: View>: View {
  @ViewBuilder var content: Content
    
  var body: some View {
    content
  }
}


// Usage
ContainerView{
  ...
}

Debugging:

1. let _ = Self._printChanges() print statement to trace view lifecycle
2. let _ = print("Update XYZView") We use this print to trace whether the body of Particular view (eg. SpyView) is executed or not.

ref: https://sarunw.com/posts/how-to-do-print-debugging-in-swiftui/

To make fullscreen view to fill entire screen:

ZStack {
   Text("Hello").background(.yellow)
}
.frame(maxWidth: .infinity, maxHeight: .infinity) // this is important
.background(.blue)