I parse Int object from API, but it's too long. So I want to cut it to two characters. I parse "6700000", but I want it to be "$6.7 m", or I parse "90000000", but I want to show "$90 m".
struct MillionView: View {
#State var rockets = [RocketInfo]()
var body: some View {
List(rockets) { rocket in
HStack {
Text("Cost per launch")
Spacer()
Text("$\(rocket.costPerLaunch) m")
}
}
.onAppear {
InfoApi().getRockets { rockets in
self.rockets = rockets
}
}
}
}
struct MillionView_Previews: PreviewProvider {
static var previews: some View {
MillionView()
}
}
I was inattentive, but then I realized that the answer was:
Text("$\(rocket.costPerLaunch / 1000000) m")
I just divided the value by a million and got the desired result.
Related
Starting with this
var body: some View {
ScrollView {
VStack(spacing: 0.0) {
Some views here
}
}
.edgesIgnoringSafeArea(.top)
}
How would I add
List(suggestions, rowContent: { text in
NavigationLink(destination: ResultsPullerView(searchText: text)) {
Text(text)
}
})
.searchable(text: $searchText)
on top if that scrollable content?
Cause no matter how I hoax this together when
#State private var suggestions: [String] = []
gets populated (non empty) the search results are not squeezed in (or, better yet, shown on top of
"Some views here"
So what I want to achieve in different terms: search field is on top, scrollable content driven by the search results is underneath, drop down with search suggestions either temporarily squeeses scrollable content down or is overlaid on top like a modal sheet.
Thanks!
If you are looking for UIKit like search behaviour you have to display your results in an overlay:
1. Let's declare a screen to display the results:
struct SearchResultsScreen: View {
#Environment(\.isSearching) private var isSearching
var results: [String]?
var body: some View {
if isSearching, let results {
if results.isEmpty {
Text("nothing to see here")
} else {
List(results, id: \.self) { fruit in
NavigationLink(destination: Text(fruit)) {
Text(fruit)
}
}
}
}
}
}
2. Let's have an ObservableObject to handle the logic:
class Search: ObservableObject {
static private let fruit = [
"Apples 🍏",
"Cherries 🍒",
"Pears 🍐",
"Oranges 🍊",
"Pineapples 🍍",
"Bananas 🍌"
]
#Published var text: String = ""
var results: [String]? {
if text.isEmpty {
return nil
} else {
return Self.fruit.filter({ $0.contains(text)})
}
}
}
3. And lastly lets declare the main screen where the search bar is displayed:
struct ContentView: View {
#StateObject var search = Search()
var body: some View {
NavigationView {
LinearGradient(colors: [.orange, .red], startPoint: .topLeading, endPoint: .bottomTrailing)
.overlay(SearchResultsScreen(results: search.results))
.searchable(text: $search.text)
.navigationTitle("Find that fruit")
}
}
}
self-learning beginner here. I am trying to show an Int from Core Data in a VStack in ContentView, not in a List. But literally all the tutorials I can find about Core Data (tracking Books, Movies, Orders, Students) are using a List to show an array containing an Int. Nothing on showing an Int by itself.
Xcode can build countnum.countnum +=1 with no problem. Seems to me it is reading it fine. But once I try to show it, it just doesn’t work. I’m wrecking my brain here.
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(sortDescriptors: []) var countnum: FetchedResults<CountNum>
var body: some View {
// let countnum = CountNum(context: moc)
VStack{
Text("+")
.padding()
.onTapGesture (count: 2){
let countnum = CountNum(context: moc)
countnum.countnum += 1
}
Text("\(countnum)") //No exact matches in call to instance method 'appendInterpolation'
}
}
}
Thanks
....all the tutorials ... show an array containing an Int. Yes, that's because CoreData
can contain many "objects". You get an array of your CountNum objects when
you do your .....var countnum: FetchedResults<CountNum>. So you need to decide which CountNum you want to
use. For example, if you want to use the first one, then:
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(sortDescriptors: []) var countnum: FetchedResults<CountNum>
var body: some View {
VStack {
if let firstItem = countnum.first {
Text("+")
.padding()
.onTapGesture(count: 2) {
firstItem.countnum += 1
do {
try moc.save()
} catch {
print(error)
}
}
Text("\(firstItem.countnum)").foregroundColor(.green)
}
}
}
}
EDIT-1: adding new CountNum to CoreData example code in the add button.
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(sortDescriptors: []) var countnum: FetchedResults<CountNum>
var body: some View {
Button(action: {add()}) { Text("add new CountNum").foregroundColor(.green) }
.padding(.top, 50)
List {
ForEach(countnum) { item in
HStack {
Text("++")
.onTapGesture(count: 2) { increment(item) }
Text("\(item.countnum)").foregroundColor(.blue)
Text("delete").foregroundColor(.red)
.onTapGesture { delete(item: item) }
}
}
}
}
func increment(_ item: CountNum) {
item.countnum += 1
save()
}
func add() {
let countnum = CountNum(context: moc)
countnum.countnum = 0
save()
}
func delete(item: CountNum) {
moc.delete(item)
save()
}
func save() {
do { try moc.save() } catch { print(error) }
}
}
I am trying to remove rows inside a ForEach. Removing the last row always throws an index out of range exception. Removing any other row does not.
ForEach(Array(player.scores.enumerated()), id: \.element) { index, score in
HStack {
if self.isEditSelected {
Button(action: {
self.player.scores.remove(at: index)
}, label: {
Image("delete")
})
}
TextField("\(score)", value: self.$player.scores[index], formatter: NumberFormatter())
}
}
I have tried using ForEach(player.indices...) & ForEach(player.scores...), but see the same problem.
Looks to me like the crash happens here self.$player.scores[index], as hardcoding the index to any value other that the last row is working.
Does anyone know how to fix this? Or if there is a better approach.
Here is fix
ForEach(Array(player.scores.enumerated()), id: \.element) { index, score in
HStack {
if self.isEditSelected {
Button(action: {
self.player.scores.remove(at: index)
}, label: {
Image("delete")
})
}
TextField("\(score)", value: Binding( // << use proxy binding !!
get: { self.player.scores[index] },
set: { self.player.scores[index] = $0 }),
formatter: NumberFormatter())
}
}
Based on #Asperi answer
public extension Binding where Value: Equatable {
static func proxy(_ source: Binding<Value>) -> Binding<Value> {
self.init(
get: { source.wrappedValue },
set: { source.wrappedValue = $0 }
)
}
}
You can use this as follows:
TextField("Name", text: .proxy($variable))
Xcode 13.0 beta introduced a new way to establish two-way-bindings between the elements of a collection and the views built by ForEach / List.
This method fixes the crash related to deleting the last row.
struct Score: Identifiable {
let id = UUID()
var value: Int
}
struct Player {
var scores: [Score] = (1...10).map {_ in .init(value: Int.random(in: 0...25))}
}
struct BindingTest: View {
#State private var player = Player()
var body: some View {
List {
ForEach($player.scores) { $score in
HStack {
TextField("\(score.value)", value: $score.value,
formatter: NumberFormatter())
}
}
.onDelete { player.scores.remove(atOffsets: $0)}
}
}
}
I have a parent view which does a #FetchRequest and passes the FetchedResults<T> to a child view. Everything works, and the child view is able to parse through the FetchedResults. However, I can't figure out how to set up the data so that the child's Preview struct will work. What's the proper way to set up some constant data in Preview struct so that I can instantiate the child view and pass in FetchedResults<T>?
As FetchedResults<T> is a RandomAccessCollection and swift array also is a RandomAccessCollection, here is possible solution.
Update: verified with Xcode 13.3 / iOS 15.4
struct ContentView: View {
#Environment(\.managedObjectContext) var context
#FetchRequest(entity: Person.entity(), sortDescriptors: [])
var result: FetchedResults<Person>
var body: some View {
VStack(alignment: .leading) {
Text("Persons").font(.title)
PersonsView(results: result) // FetchedResults<Person> is a collection
}
}
}
// generalize PersonsView to depend just on collection
struct PersonsView<Results:RandomAccessCollection>: View where Results.Element == Person {
let results: Results
var body: some View {
ForEach(results, id: \.self) { person in
Text("Name: \(person.name ?? "<unknown>")")
}
}
}
// Tested with Xcode 11.4 / iOS 13.4
// DOES NOT WORK ANYMORE !!
// struct ChildView_Previews: PreviewProvider {
// static var previews: some View {
// PersonsView(results: [Person()]) // << use regular array //to test
// }
}
Update: fixed & tested part for Xcode 12 / iSO 14 (due to crash of above PreviewProvider)
It appears entity now should be read & specified explicitly:
struct ChildView_Previews: PreviewProvider {
static let entity = NSManagedObjectModel.mergedModel(from: nil)?.entitiesByName["Person"]
static var previews: some View {
let person = Person(entity: entity!, insertInto: nil)
person.name = "Test Name"
return PersonsView(results: [person])
}
}
Use the preview PersistenceController within your pre-generated PersistenceController struct (inside the "Persistence.swift" file).
so if you pass an item from a Core Data "Item"-entity:
struct ContentView: View {
...
private var items: FetchedResults<Item>
..
ForEach(items) { item in
DetailView(item: item)
}
..
In the Detail-View go like this:
struct DetailView: View {
var item: FetchedResults<Item>.Element
var body: some View {
Text("Items text = \(item.text ?? "")")
}
}
struct Detail_Previews: PreviewProvider {
static var previews: some View {
let viewContext = PersistenceController.preview.container.viewContext
let previewItem = Item(context: viewContext)
previewItem.text = "Text4preview"
return Detail(item: previewItem)
}
}
Assume I build a view like this:
struct MyView: View {
#State private var a: String
#State private var b: String
#State private var c: String
var body: some View {
VStack {
HStack {
Text(a)
// this is the central view
Text(b).font(.headline)
}
Text(c)
}
}
}
I would like the central text view (the one displaying b) to be the anchor of the layout. That is, no matter how other text values change, I would like the central text to always stay in the centre of MyView (the centre of the text element and the centre of MyView should stay identical) and the other text elements should be laid out around the central one.
How to I achieve this? I tried to look at alignment guides, but I just don't seem to understand how to use them properly.
After spending some time to learn how alignment works in detail, I managed to arrive at a solution that only uses stacks and custom alignments, with minimal alignment guides and without needing to save any intermediate state. It's purely declarative, so I am supposed this is how SwiftUI designers intended it. I still think that there might have been a better design for it, but one can work with it.
struct ContentView: View {
#State var a: String = "AAAAA"
#State var b: String = "BBBB"
#State var c: String = "CCCCCC"
var body: some View {
VStack {
ZStack(alignment: .mid) {
// create vertical and horizontal
// space to align to
HStack { Spacer() }
VStack { Spacer() }
VStack(alignment: .midX) {
Text(self.a)
HStack(alignment: .center) {
Text(self.c)
Text(self.b)
.font(.title)
.border(Color.blue)
.alignmentGuide(.midX) { d in
(d[.leading] + d[.trailing])/2
}
.alignmentGuide(.midY) { d in
(d[.top] + d[.bottom])/2
}
}
}
}
.layoutPriority(1.0)
.overlay(CrossHair().stroke(Color.pink, lineWidth: 2))
TextField("", text: self.$b).textFieldStyle(RoundedBorderTextFieldStyle())
}
}
}
fileprivate extension HorizontalAlignment {
enum MidX : AlignmentID {
static func defaultValue(in d: ViewDimensions) -> CGFloat {
return (d[.leading] + d[.trailing])/2
}
}
static let midX = HorizontalAlignment(MidX.self)
}
fileprivate extension VerticalAlignment {
enum MidY : AlignmentID {
static func defaultValue(in d: ViewDimensions) -> CGFloat {
return (d[.top] + d[.bottom])/2
}
}
static let midY = VerticalAlignment(MidY.self)
}
fileprivate extension Alignment {
static let mid = Alignment(horizontal: .midX, vertical: .midY)