Ray Wenderlich Course - SwiftUI (Part 3)

Cracking on with SwiftUI! As I've said, this has been a tricky course but I'm learning plenty. Let's continue!

 Start Time - 19:55

Slider and Stepper

Stepper - plus or minus a value (buttons for this)
Slider - as with bullseye

State - use of @State and the $ symbol.

struct ContentView: View {
    
    @ State private var orderCount = 0
  var body: some View {
    VStack {
        Stepper(onIncrement: { self.orderCount += 1
            
        } , onDecrement: { }) {
            Text("Set order amount")
        }
    }
  }

}

A bit about state - this is a value that can change and will update accordingly. 

So this is a lot easier!

 Stepper("Set order amount", value: $orderCount)
Slider(value: $houseTemperature, in: (30...120))
    Text("\(houseTemperature)"))


A nice bit here for Stepper and Slider. I will experiment with those!

Date Picker and Toggle

Date Picker - storing the date. Depending what info you want!

So another use of the @State - it is about passing in a value that is binded, rather than a straight value into the object, in this case a toggle...

@State var isCatNipOn = false
    var body: some View {
      VStack {
        Toggle("Activate cat nip", isOn: $isCatNipOn)
      }
    }

A couple of really good uses of the ternary operator, rather than an if statement! The below is also a computed property. 

 var isActivatedMessage: String {
        return "Cat nip is " + (isCatNipOn ? "Activated!": "Deactivated!")
    }

And again but with a text property - cool!

Text(isActivatedMessage)

            .foregroundColor(isCatNipOn ? .green: .red)


So lots of cool stuff here! I've learned about toggle and date picker. Definitely want to try these out and explore more!


struct ContentView: View {
    
    var isActivatedMessage: String {
        return "Cat nip is " + (isCatNipOn ? "Activated!": "Deactivated!")
    }
    
    var dateFormatter: DateFormatter {
        let dateFormatter = DateFormatter()
        dateFormatter.dateStyle = .short
        return dateFormatter
    }
    
    @State var isCatNipOn = false
    @State var pickedDate = Date()
    
    
    var body: some View {
      VStack {
        Toggle("Activate cat nip", isOn: $isCatNipOn)
        Text(isActivatedMessage)
        .foregroundColor(isCatNipOn ? .green: .red)
            .fontWeight(isCatNipOn ? .heavy: .regular)
        
        Toggle(isOn: $isCatNipOn) {
            VStack {
                Image("CatNip")
                    .resizable()
                    .frame(width: 100, height: 100)
                Text("Activate cat nip!")
                
            }
        }
        
        DatePicker(selection: $pickedDate, displayedComponents: [.date]) {
            Text("Select Date")
        }
        
        Text("\(dateFormatter.string(from: pickedDate))")
        
      }
    }
}
     

 And there we go! Part 1 complete of this course. Three more parts to go, so I reckon at least another couple of weeks for this SwiftUI course. I'm learning plenty - the next challenge will be putting it all into practice. 

Finish Time - 20:43 (48 minutes)

Summary - 

  • How to create different objects (slider, stepper, date picker and toggle)
  • What @State means and why we need this and the $
  • Use of ternary operator in context
  • Using ternary to choose different properties



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