I have an array of custom class and I want to make a change to one of the items in it.
var mainArray = [MainOrder]()
//Now imagine that mainArray has a bunch of different items in it.
struct MainOrder:Codable {
var time:Date?
var order_id:String?
var side:String?
}
What is the best way to do that? Right now I find the index then I move it into a new variable then I delete the item from the array and then add it back again like you see below. But I am sure this is better way to do this.
if let tempIndex = self.mainArray.index(where: {$0.side == "left"}) {
var tempVar = self.mainArray[tempIndex]
tempVar.time = Date()
self.mainArray.remove(at: tempIndex)
self.mainArray.insert(tempVar, at: tempIndex)
}
You just need the following:
if let tempIndex = self.mainArray.index(where: {$0.side == "left"}) {
mainArray[tempIndex].time = Date()
}
Here's a complete example demonstrating that this works:
struct MainOrder:Codable,CustomStringConvertible {
var time:Date?
var order_id:String?
var side:String?
var description: String {
return "time: \(time), order_id: \(order_id), side: \(side)"
}
}
var mainArray = [MainOrder]()
mainArray.append(MainOrder(time: nil, order_id: "hi", side: "left"))
print(mainArray)
if let tempIndex = self.mainArray.index(where: {$0.side == "left"}) {
mainArray[tempIndex].time = Date()
}
print(mainArray)
Output:
[time: nil, order_id: Optional("hi"), side: Optional("left")]
[time: Optional(2018-01-13 01:59:06 +0000), order_id: Optional("hi"), side: Optional("left")]
If you can guarantee there will always be an object in the array with the matching side value, you can force this all into one line:
mainArray[mainArray.index(where: { $0.side == "left" })!].time = Date()
But this will crash if your assumption is wrong. Be safe and do with the if let.
Declare it as class so it will be reference type
class MainOrder:NSObject,Codable {
var time:Date?
var order_id:String?
var side:String?
}
Edit item directly
var tempVar = self.mainArray[tempIndex]
tempVar.time = Date()
Related
I'm tryin' to obtain a list of activities ("dd/mm/YY: goal achieved/missed goal") which has to be setted every week. The problem is that I obtain a list of activities with the same date and the same result of the previous one. For example:
28/02/2022: goal achieved
28/02/2022: goal achieved
28/02/2022: goal achieved
and the next day:
01/03/2022: missed goal
01/03/2022: missed goal
01/03/2022: missed goal
01/03/2022: missed goal
I want to obtain, instead, a list like:
28/02/2022: goal achieved
01/03/2022: missed goal
02/03/2022: goal achieved...
These are useful structs:
struct Persistent {
#AppStorage("goalAchieved") static var goalAchieved : Bool = false
#AppStorage("activityList") static var activityList : [String] = []
}
struct obj {
static var currentDate = Date()
static var stringDate = ""
static var activity = Activity(date:Persistent.lastUpdatedDate)
}
This is the ActivityListView:
import SwiftUI
func activitystring(activity:Activity) -> String{
var output = ""
output = "\(activity.date): \(activity.reachedobj(goalAchieved: Persistent.goalAchieved))"
return output
}
struct Activity: Identifiable{
let id = UUID()
let date: String
func reachedobj(goalAchieved: Bool) -> String {
var output = ""
if Persistent.goalAchieved == false { output = "Missed goal" }
if Persistent.goalAchieved == true { output = "Goal Achieved!"}
return output
}
}
struct ActivityRow: View{
var activity: Activity
var body: some View{
Text(activitystring(activity: activity))
Divider()
}
}
struct ActivityListView: View {
var body: some View {
ScrollView{
Text("Week summary").font(.system(size: 15)).foregroundColor(Color.green)
Text("")
ForEach(Persistent.activityList, id: \.self) { activity in
let activity = Activity(date: Persistent.lastUpdatedDate)
ActivityRow(activity: activity)
}
}
}
}
Finally this is the useful code in the ApplicationApp file (main) where I update activity list:
MenuView().onAppear(){
if Persistent.activityList.count>7{
Persistent.activityList.removeAll()
}
obj.currentDate = Date()
let formatter = DateFormatter()
formatter.dateFormat = "dd/MM/YY"
obj.stringDate = formatter.string(from:obj.currentDate)
if Persistent.lastUpdatedDate != obj.stringDate{
Persistent.goalAchieved = false
let activity = Activity(date: Persistent.lastUpdatedDate)
Persistent.activityList.append(activitystring(activity: activity))
Persistent.lastUpdatedDate = obj.stringDate
}
}
What's wrong on this?
You're calling obj.activity in your ForEach and ActivityRow, that's why it repeats that same static property all over the place.
You better just drop your struct obj and try again without it
In your Persistent object you have an array of many activities, called activitylist , but one single boolean that tells if the goal is achieved - goalachieved indeed.
Your view is iterating through the array of Persistent.activitylist, so you will have many lines for one single result - achieved or not achieved. You might actually want to iterate over an array of Persistent objects - meaning that somewhere you should probably store [Persistent] in some variable. In this way, you will see one line only for each result.
If I also may suggest: use the conventions for naming variables, Swift uses "camelCaseConventionForVariables", easier to read than "thewholevariableislowercase"
Edit:
Let me try to change a little bit your code (I would personally change it more radically, but that's not the scope of the answer).
Instead of having only one goalAchieved for all elements on the array activityList, make it a dictionary:
struct Persistent {
// Drop this variable
// #AppStorage("goalAchieved") static var goalAchieved : Bool = false
// Make this a dictionary, the date will be the key and the goalAchieved will be the value
#AppStorage("activityList") static var activityList : [String: Bool] = [:]
}
Add values to the dictionary (#meomeomeo is right, you don't need obj):
MenuView().onAppear() {
if Persistent.activityList.count > 7 {
Persistent.activityList.removeAll()
}
let currentDate = Date()
let formatter = DateFormatter()
formatter.dateFormat = "dd/MM/YY"
let stringDate = formatter.string(from: currentDate)
if Persistent.lastUpdatedDate != stringDate {
let activity = Activity(date: Persistent.lastUpdatedDate)
Persistent.activityList[activitystring(activity: activity))] = false // Will create something like ["01/03/2022": false]
Persistent.lastUpdatedDate = stringDate
}
}
Iterate on the dictionary in your ForEach; for more info: read here.
I have a tableView with different kinds of infos, each coming from a different array.
I could not work with dictionaries because then the list would have been unordered and I could not work with classes, because I have different lists with all kinds of dynamic entries (properties are always different etc.)
Here my problem:
I want to implement a search function. But when I use the filter function for one array, it changes of course based on the implemented condition but the other 5 stay the same => I can't reload the tableView because the array information does not match anymore ...
Here the arrays:
var categoryItemUIDs = [String]()
var categoryItemDescriptions = [String]()
var categoryItemLfdNrs = [Int]()
var categoryGivenOuts = [Bool]()
var categoryGivenTos = [String]()
var categoryGivenAts = [String]()
var categoryStorageLocations = [String]()
In the tableView(cellForRowAtIndexPath method):
cell.customTextLabel?.text = categoryItemLfdNrs[indexPath.row]
cell.customDetailTextLabel.text = categoryItemDescriptions[indexPath.row]
Here the searchBar(textDidChange) method:
self.categoryItemDescriptions.filter { $0.lowercased().contains(searchText.lowercased()) }
Now I get an array back with reduced size, but all the other arrays stay the same... Is there maybe another way to avoid this problem? I already tried type aliases but it did not work out.
I would appreciate any help!
Kind regards,
When it goes to such a big count of arrays, the time for your specific type comes.
The simple solution is to create something like
struct Category {
var uid: String
var description: String
// ...
var storageLocation: String
}
The you have simply something like
var items: [Category]
And you can still do simple things in cellForRowAtIndexPath
cell.customTextLabel?.text = items[indexPath.row].lfdnrs
cell.customDetailTextLabel.text = items[indexPath.row].description
And only 1 array to filter
items.filter { $0.description.lowercased().contains(searchText.lowercased()) }
So overall advice is to solve different problem (here I suggested the solution of the having your data in the app problem instead of filtering multiple arrays with one condition)
try
var categoryItemUIDs = ["aaa","bbb","ccc"]
var categoryItemDescriptions = ["ddd","eee","fff"]
var categoryItemLfdNrs = [0,1,2]
struct data {
var id = ""
var desc = ""
var item = 0
init(id :String, desc:String, item:Int)
{
self.id = id
self.desc = desc
self.item = item
}
}
//var cat = [data]()
//for i in 0..<categoryItemUIDs.count {
// cat.append(data(id:categoryItemUIDs[i], desc:categoryItemDescriptions[i],item:categoryItemLfdNrs[i] ))
//}
//more swift
let cat = (0..<categoryItemUIDs.count).map { (i) -> data in
return data(id:categoryItemUIDs[i], desc:categoryItemDescriptions[i],item:categoryItemLfdNrs[i] )
}
print (cat)
let catFilter = cat.filter { $0.id == "aaa" }
print (catFilter)
Hi there I am new to Swift, I am trying to save Longitude and Latitude and place name from map's coordinate object to an Multidimensional array i.e:
Can anyone please help me how do i create these dynamically?
var pinArray[0][Lat] = 51.130231
var pinArray[0][Lon] = -0.189201
var pinArray[0][Place] = "Home"
var pinArray[1][Lat] = 52.130231
var pinArray[1][Lon] = -1.189201
var pinArray[1][Place] = "Office"
var pinArray[2][Lat] = 42.131331
var pinArray[2][Lon] = -1.119201
var pinArray[2][Place] = "Dinner"
You can make an array of dictionaries, but I suggest using structs instead.
Array of dictionaries
Create an empty array of dictionaries:
var pinArray = [[String:AnyObject]]()
Append dictionaries to the array:
pinArray.append(["lat":51.130231, "lon":-0.189201, "place":"home"])
pinArray.append(["lat":52.130231, "lon":-1.189201, "place":"office"])
But since your dictionaries hold two types of value (Double and String) it will be cumbersome to get the data back:
for pin in pinArray {
if let place = pin["place"] as? String {
print(place)
}
if let lat = pin["lat"] as? Double {
print(lat)
}
}
So, better use structs instead:
Array of structs
Create a struct that will hold our values:
struct Coordinates {
var lat:Double
var lon:Double
var place:String
}
Create an empty array of these objects:
var placesArray = [Coordinates]()
Append instances of the struct to the array:
placesArray.append(Coordinates(lat: 51.130231, lon: -0.189201, place: "home"))
placesArray.append(Coordinates(lat: 52.130231, lon: -1.189201, place: "office"))
It's then easy to get the values:
for pin in placesArray {
print(pin.place)
print(pin.lat)
}
Without more information, this is what I can offer.
var pinArray = [[AnyObject]]()
for location in mapLocations {
var innerArray = [location["latitude"], location["longitude"], location["place"]]
pinArray.append(innerArray)
}
Solution using an enum for Lat/Lon/Place (as you don't show us what these are):
enum Pos {
case Lat
case Lon
case Place
static let allPositions = [Lat, Lon, Place]
}
var myMatrix = [[Pos:Any]]()
myMatrix.append([.Lat: 51.130231, .Lon: -0.189201, .Place: "Home"])
myMatrix.append([.Lat: 52.130231, .Lon: -1.189201, .Place: "Office"])
myMatrix.append([.Lat: 42.131331, .Lon: -1.119201, .Place: "Dinner"])
/* check */
for (i,vector) in myMatrix.enumerate() {
for pos in Pos.allPositions {
print("myMatrix[\(i)][\(pos)] = \(vector[pos] ?? "")")
}
}
/*
myMatrix[0][Lat] = 51.130231
myMatrix[0][Lon] = -0.189201
myMatrix[0][Place] = Home
myMatrix[1][Lat] = 52.130231
myMatrix[1][Lon] = -1.189201
myMatrix[1][Place] = Office
myMatrix[2][Lat] = 42.131331
myMatrix[2][Lon] = -1.119201
myMatrix[2][Place] = Dinner */
In Swift playground, I'm using a for loop to insert items. During the loop it seems to be adding the right values. At the end of the for loop, when the array is all filled up, when I query, it shows only the value which was inserted last at each index.
New to swift, so I guess am doing something really stupid here... Need help...
The code is as below:
class card {
var suit: String = ""
var rank: String = ""
}
var card1 = card()
var deck = [card]()
var playingCard = card()
var suits = ["♠︎","♣︎","♥︎","♦︎"]
var ranks = ["A","K","Q","J","10","9","8","7","6","5","4","3","2"]
let countRanks = ranks.count
let countSuits = suits.count
var ctr = 0
for i in 0..<countSuits {
for j in 0..<countRanks {
playingCard.rank = ranks[j]
playingCard.suit = suits[i]
deck.insert(playingCard, atIndex: 0)
println("\(deck[ctr].suit)"+"\(deck[ctr].rank)")
ctr++
}
}
let x = deck.count
for i in 0..<x {
println("\(deck[i].rank)"+"\(deck[i].suit)")
}
class instances are reference types. You need to create a new card instance for each iteration. Move the line var playingCard = card() right after the for j in 0..<countRanks line and change var to let
You need to initialise a new instance of playingCard each iteration:
for i in 0..<countSuits {
for j in 0..<countRanks {
var playingCard = card()
...
}
}
I would also suggest you add an init method for your card class to make it easier to initialise:
class Card {
var suit: String
var rank: String
init(suit: String, rank: String) {
self.suit = suit
self.rank = rank
}
}
...
var playingCard = Card(suit: suits[i], rank: ranks[j])
I'm getting a: Cannot invoke 'append' with an argument list of type '([Book])' It works find if I use the += but I don't understand why append() won't work.
struct Book
{
var title:String
var pageCount:Int
}
class Library
{
var onShelfBooks:[Book] = []
var onLoanBooks:[Book] = []
var books:[Book]
{
get
{
return onShelfBooks + onLoanBooks
}
set(newBook)
{
onShelfBooks.append(newBook)
}
}
}
struct Book
{
var title:String
var pageCount:Int
}
class Library
{
var onShelfBooks:[Book] = []
var onLoanBooks:[Book] = []
var books:[Book]
{
get
{
return onShelfBooks + onLoanBooks
}
set(newBook)
{
onShelfBooks.append(newBook[0])
}
}
}
var myLibrary = Library()
var newBook = Book(title: "Swift Development with Cocoa", pageCount: 453)
myLibrary.books = [newBook]
myLibrary.books
Append only allows you to add one object at a time while += allows you to combine an array of objects with another object. When you call append on the setter you are trying to add an array of book objects, or [Book] instead of just a single book object.
If you would like to add [newBook] with append, you can use : of
1- onShelfBooks.append(contentsOf: newBook)
"contentOf" is type of Sequence.
otherwise use of:
2- onShelfBooks += newBook