Making a Drop Down List Using Swift

Making a drop down list using swift?

A 'drop down menu' is a web control / term. In iOS we don't have these. You might be better looking at UIPopoverController. Check out this tutorial for a bit of an insight to PopoverControllers

http://www.raywenderlich.com/29472/ipad-for-iphone-developers-101-in-ios-6-uipopovercontroller-tutorial

How to create dropdown in Swift UI?

You can use the combination of GroupBox and DisclosureGroup to achieve what you're looking for, you can modify below code according to your requirements

import SwiftUI

struct ContentView: View {
    //MARK: - PROPERTIES
    
    let nutrients: [String] = ["Energy", "Sugar", "Fat", "Protein", "Vitamins", "Minerals"]
    
    //MARK: - BODY
    
    var body: some View{
        GroupBox(){
            DisclosureGroup("Nutritional value per 100g") {
                ForEach(0..<nutrients.count, id: \.self){ index in
                    Divider()
                        .padding(.vertical, 2)
                    
                    HStack{
                        Group{
                            Image(systemName: "info.circle")
                            Text(nutrients[index])
                        }//: GROUP
                        .foregroundColor(.gray)
                        .font(.system(.body).bold())
                        
                        Spacer(minLength: 25)
                        
                        Text("1g")
                            .multilineTextAlignment(.trailing)
                    }//: HSTACK
                }//: LOOP
            }//: DISCLOSURE
        }//: BOX
    }
}

//MARK: - PREVIEW

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

You can customise Toggle with .toggleStyle modifier, first you have to create your style like this

struct CheckboxStyle: ToggleStyle {
func makeBody(configuration: Configuration) -> some View {
    return HStack{
        //IMAGE
        Image(systemName: configuration.isOn ? "checkmark.square" : "square")
            .font(.system(size: 30, weight: .semibold, design: .rounded))
            .onTapGesture {
                configuration.isOn.toggle()
            }
        
        //LABEL
        configuration.label
    }//: HSTACK
}
}

and then apply it on your Toggle like this

Toggle("Placeholder label", isOn: .constant(true))
        .toggleStyle(CheckboxStyle())

How to create a drop down menu

It's alertController with actionSheet. User this method in your button action for example.

func handleAlert()
  let alertController = UIAlertController(title: "Change Profile Photo", message: nil, preferredStyle: .actionSheet)
  //First action
  alertController.addAction(UIAlertAction(title: "Remove current photo", style: .destructive, handler: { (_) in
        // Your remove photo code here
    }))
  alertController.addAction(UIAlertAction(title: "Import From Facebook", style: .default, handler: { (_) in
        // Your import from facebook code here
    }))
  //Cancel action
  alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
  present(alertController, animated: true, completion: nil)
}

Dropdown list in swift

There are a number ways to do it, my suggestions would be something similar to as follows:

When you initialise the view controller, your dropdown view is offset and hidden behind the navigation bar. Do this either with Layout Constraints or using the view's frame, depending on your preferred set up.

var isAnimating: Bool = false
var dropDownViewIsDisplayed: Bool = false

func viewDidLoad() {
    super.viewDidLoad()
    let height: CGFloat = self.dropDownView.frame.size.height
    let width: CGFloat = self.dropDownView.frame.size.width
    self.dropDownView.frame = CGRectMake(0, -height, width, height)
    self.dropDownViewIsDisplayed = false
}

Then link up an action to the BarButtonItem that, when pressed, displays the view if hidden or hides if visible using an animation.

@IBAction func barButtonItemPressed(sender: UIBarButtonItem?) {
    if (self.dropDownViewIsDisplayed) {
        self.hideDropDownView()
    } else {
        self.showDropDownView()
    }
}

func hideDropDownView() {
     var frame: CGRect = self.dropDownView.frame
     frame.origin.y = -frame.size.height
     self.animateDropDownToFrame(frame) {
         self.dropDownViewIsDisplayed = false
     }
}

func showDropDownView() {
    CGRect frame = self.dropDownView.frame
    frame.origin.y = self.navigationBar.frame.size.height
    self.animateDropDownToFrame(frame) {
        self.dropDownViewIsDisplayed = true
    }
}

func animateDropDownToFrame(frame: CGRect, completion:() -> Void) {
    if (!self.animating) {
        self.animating = true
        UIView.animateWithDuration(0.5, delay: 0.0, options: .CurveEaseInOut, animations: { () -> Void in
            self.dropDownView.frame = frame
            }, completion: (completed: Bool) -> Void in {
                self.animating = false
                if (completed) {
                     completion()
                }
            })
    }
}

All that is left for you is to define your dropDownView and link it up correctly.

I hope that helps, please comment if there is anything you don't understand

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