In Java, I use static block to execute some code when the class is called like in this example"
Class Name
{
static
{
for(int i = 0; i<10; i++)
{
}
}
}
How do I translate that code in Swift?
You could do something like this,.
class SomeViewController : UIViewController {
public static let formatter: DateFormatter = {
let df = DateFormatter()
df.dateFormat = "yyyy-MM-dd"
return df
}()
}
I have been struggling with this same question for the last couple days. The solution that I found (although somewhat inelegant) is the use of main.swift.
This isn't really the same thing as a static block on a class in Java, but it may help with your particular issue.
Related
Lately I have found a snag in my code. I'm working with my custom objects and arrays of them. I have found one case in which push() method is working and the other one in which it isn't.
First case (working ok):
class MyObject{
private reference: d3.Selection<SVGElement>;
public constructor(ref: d3.Selection<SVGElement>){
this.reference = ref;
}
}
interface ViewModel{
objects: MyObject[]
}
class MyApp{
private root: d3.Selection<SVGElement>
private viewModel: ViewModel;
constructor(options: Type){
this.root = options.root
this.viewModel.objects.push(new MyObject(this.root))
}
}
Second case (not working):
class MyObject{
private reference: d3.Selection<SVGElement>;
public constructor(ref: d3.Selection<SVGElement>){
this.reference = ref;
}
}
class MyApp{
private root: d3.Selection<SVGElement>
private objects: MyObject[];
constructor(options: Type){
this.root = options.root
this.objects.push(new MyObject(this.root)) //seems to freeze the whole program
}
}
What am I doing wrong?
Any help would be greatly appreciated.
Michal
You have not initialised your objects array yet:
private objects: MyObject[] = [];
That might work :)
Although, you have not initialised your viewModel in your 'working' example. So I suppose you posted a stripped version of your code?
I built a custom class which holds an "internal" array and offers some useful methods.
class ArrayList<T> {
private var array : Array<T>
public init() {
array = Array<T>()
}
public func add(element : T) {
array.append(element)
}
public func size() -> Int {
return array.count
}
...
}
Ok, that works fine for me so far.
But now I also want to have a method to sort the array. What I already have is the following:
public func sort(comparator : ?) {
array = array.sort(comparator)
}
The question mark stands for the parameter type and that is my problem: Which type must the parameter have? I read something about #noescape<,> but I can't get it to work!
I'm using Swift 2.2.
The easiest way is the use the standard closure
public func sort(comparator : (T, T) -> Bool) {
array.sortInPlace(comparator)
}
and constrain the generic type to the Comparable protocol
class ArrayList<T : Comparable>
Then you can use this code
let arrayList = ArrayList<Int>()
arrayList.add(5)
arrayList.add(12)
arrayList.add(10)
arrayList.add(2)
arrayList.sort { $0 < $1 }
print(arrayList.array) // [2, 5, 10, 12]
This question already has answers here:
Serialize and Deserialize Json and Json Array in Unity
(9 answers)
Closed 5 years ago.
I need to save multiple player's data. I am doing it by making an array of PlayersInfo class and trying to convert the array into JSON. here is my code
PlayerInfo[] allPlayersArray = new PlayerInfo[1];
allPlayersArray[0] = new PlayerInfo();
allPlayersArray[0].playerName = "name 0";
string allPlayersArrayJson = JsonUtility.ToJson(allPlayersArray);
print(allPlayersArrayJson);
PlayerPrefs.SetString("allPlayersArrayJson", allPlayersArrayJson);
string newJson = PlayerPrefs.GetString("allPlayersArrayJson");
print(newJson);
PlayerInfo[] newArray = new PlayerInfo[1];
newArray = JsonUtility.FromJson<PlayerInfo[]>(newJson);
print(newArray[0].playerName);
First two print statements returns "{}" and 3rd one gives null reference error. TIA
Like I said in my comment, there is no direct support. Helper class is needed. This is only reason I am making this answer is because you are still having problems even after reading the link I provided.
Create a new script called JsonHelper. Copy and paste the code below inside it.
using UnityEngine;
using System.Collections;
using System;
public class JsonHelper
{
public static T[] FromJson<T>(string json)
{
Wrapper<T> wrapper = UnityEngine.JsonUtility.FromJson<Wrapper<T>>(json);
return wrapper.Items;
}
public static string ToJson<T>(T[] array)
{
Wrapper<T> wrapper = new Wrapper<T>();
wrapper.Items = array;
return UnityEngine.JsonUtility.ToJson(wrapper);
}
[Serializable]
private class Wrapper<T>
{
public T[] Items;
}
}
The code in your question should now work. All you have to do is to replace all JsonUtility words with JsonHelper. I did that for you below:
void Start()
{
PlayerInfo[] allPlayersArray = new PlayerInfo[1];
allPlayersArray[0] = new PlayerInfo();
allPlayersArray[0].playerName = "name 0";
string allPlayersArrayJson = JsonHelper.ToJson(allPlayersArray);
print(allPlayersArrayJson);
PlayerPrefs.SetString("allPlayersArrayJson", allPlayersArrayJson);
string newJson = PlayerPrefs.GetString("allPlayersArrayJson");
print(newJson);
PlayerInfo[] newArray = new PlayerInfo[1];
newArray = JsonHelper.FromJson<PlayerInfo>(newJson);
print(newArray[0].playerName);
}
Based on the JsonUtility documentation, naked arrays are not supported. Put the array inside a class.
Internally, this method uses the Unity serializer; therefore the
object you pass in must be supported by the serializer: it must be a
MonoBehaviour, ScriptableObject, or plain class/struct with the
Serializable attribute applied.
In general, you'll use this to serialize MonoBehaviour objects, or a custom class/struct with the Serializable attribute.
YES! It is not supported currently but there is always a work around. Use this class :
public static class JsonHelper
{
public static T[] getJsonArray<T>(string json)
{
try
{
string newJson = "{ \"array\": " + json + "}";
Wrapper<T> wrapper = JsonUtility.FromJson<Wrapper<T>> (newJson);
return wrapper.array;
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
[Serializable]
private class Wrapper<T>
{
public T[] array = null;
}
}
I would use Json.NET
PlayerInfo[] allPlayersArray = new PlayerInfo[] { p1, p2, p3 };
string json = JsonConvert.SerializeObject(allPlayersArray);
More On SerializeObject
(Code example not yet tested)
I have the following test class
public class Driver
{
public static void main(String [] args)
{
BankAccount[] b1 = {new BankAccount(200), new BankAccount(300), new BankAccount(250), new BankAccount(300), new BankAccount(200)};
BankAccountGroup bag = new BankAccountGroup(b1);
}
And BankAccountGroup:
public class BankAccountGroup
{
private BankAccount bank[];
public BankAccountGroup(BankAccount[]b)
{
for(int i =0; i<5;i++)
{
bank[i] = b[i];
}
}
these are just snippets of the whole code. Im getting a nullpointerexception for these two lines:
- bank[i] = b[i];
- BankAccountGroup bag = new BankAccountGroup(b1);
Please help
When you declare bank[] in the BankAccountGroup class it looks like you forgot to give it a length. Because of this, when you call bank[i] in your for loop, anything after i=0 is probably going to give you an error.
something like
private BankAccount[] bank = new BankAccount[5];
Either initialize your array first(Bad).
Or assign it from the value you pass the constructor.
private BankAccount[] bank;
public BankAccountGroup(BankAccount []){
bank = b;
}
You are not initializing the bank array. You also shouldn't assume that the argument will have a length of 5 elements. I would rewrite the class to something like this:
public class BankAccountGroup
{
private BankAccount bank[];
public BankAccountGroup(BankAccount[]b)
{
if (b != null)
{
bank = new BankAccount[b.length];
for(int i=0; i<b.length;i++)
{
bank[i] = b[i];
}
}
}
}
I have encountered quite a challenging one and I'd love to get some support.
Here is the scenario :
The main Game class instances the Level1 Class in charge for spawning enemies through nested For loops and push them to an array.
It then checks for collisions between the Bullet and Enemy and if it find a collision it calls a method in the Enemy class that removes removeChild and Splice itself from the array.
The thing is it works for the first few enemies, and then it will pick the wrong Enemy to destroy, and stop completely to function.
I tried using indexOf to be sure I am referring to the right object, but to no avail.
I think the Pslice and removeChild are pointing to different objects.
This mess happended when I moved the removeChild and splice from the Game Class to the Enmy class
Link to the work in progress : https://dl.dropboxusercontent.com/s/69hcmzygnkx7h1e/space_shooter.swf
I'd like some help on this one.
Thank you !!!
Main class : Game.AS
package
{
import flash.display.MovieClip;
import flash.events.MouseEvent;
import flash.events.Event;
import flash.text.*;
import flash.geom.Point;
public class Game extends MovieClip
{
public var _instance : Game;
public var player:Player;
public static var level1:Level1;
public var bullet:Bullet;
private var bullets_arr:Array;
var fire_on : Boolean;
var fire_counter : int;
public function Game()
{
level1=new Level1(this.stage);
player = new Player ;
addChild(player);
player.y = 600;
bullets_arr = [];
addEventListener(Event.ENTER_FRAME,Main);
stage.addEventListener(MouseEvent.MOUSE_DOWN,mouseDownHandler);
stage.addEventListener(MouseEvent.MOUSE_UP,mouseUpHandler);
}
function mouseDownHandler($e:MouseEvent):void
{
fire_on = true;
}
function mouseUpHandler($e:MouseEvent):void
{
fire_on = false;
fire_counter = 0;
}
function fire():void
{
bullet = new Bullet ;
addChild(bullet);
bullet.x = player.x;
bullet.y = player.y - 32;
bullets_arr.push(bullet);
}
public function Main(e: Event):void
{
player.x = mouseX;
if (bullets_arr)
{
for (var m:int = 0; m < bullets_arr.length; m++)
{
bullets_arr[m].y -= 20;
if(Game.level1.enemies_arr)
{
for (var n:int = 0; n < Game.level1.enemies_arr.length; n++)
{
if (Game.level1.enemies_arr[n].hitTestObject(bullets_arr[m]))
{
if(bullets_arr[m].parent)
{
bullets_arr[m].parent.removeChild(bullets_arr[m]);
bullets_arr.splice(bullets_arr[m],1);
Game.level1.enemies_arr[n].Damage(10, Game.level1.enemies_arr[n]);
}
}
}
}
}
}
if(fire_on)
{
fire_counter++;
if(fire_counter == 01)
{
fire();
}
else if(fire_counter >2)
{
fire_counter =0;
}
}
}
}
}
Level1.as where the enemies are spawned and pushed to the array.
package
{
import flash.display.MovieClip;
import flash.display.Stage;
import flash.events.Event;
public class Level1 extends MovieClip
{
var i:int;
var j:int;
var frame :int;
public var enemy:Enemy;
public var enemies_arr:Array;
public function Level1(target:Stage)
{
frame = 0;
enemies_arr = [];
for (var i:int = 0; i < 5; i++)
{
for (var j:int = 0; j < 3; j++)
{
enemy = new Enemy;
enemy.x = j*100 + 260;
enemy.y = i*40 - 150;
target.addChild(enemy);
enemies_arr.push(enemy);
trace(enemy.parent);
}
}
}
}
}
The Enemy class Enemy.AS
package
{
import flash.display.MovieClip;
public class Enemy extends MovieClip
{
var Health : int;
function Enemy()
{
Health =2;
}
public function Damage(Damage:int, enemyHit:Enemy)
{
Health -= Damage;
if (Health <1)
{
Die(enemyHit);
}
}
private function Die(enemyHit:Enemy)
{
if(enemyHit.parent)
{
this.parent.removeChild(this);
Game.level1.enemies_arr.splice(Game.level1.enemies_arr.indexOf(enemyHit,1));
}
}
}
}
You should traverse both Game.level1.enemies_arr and bullets_arr backwards. The point is, splice() shortens the array, shifts the elements that are in greater positions than the spliced one(s) to lesser indexes, and the loop counter is not automatically adjusted. The error is pretty common, but is often overlooked. Also, with bullets_arr you can get out of the array causing a 1009 error if your last bullet out of bullets_arr will hit an enemy.
A small nitpick: You are checking for the array's existence within a loop, and for another array's existence once within the enter frame listener. In fact you should either initialize them with at least new Array() or [] before you add an event listener to the Main object, or wherever this is assigned to, or check like if (!bullets_arr) bullets_arr=new Array(); and leave it at that, so one check of the array's existence will be needed.
public function Main(e: Event):void
{
player.x = mouseX;
if (!bullets_arr) bullets_arr=new Array();
if (!Game.level1.enemies_arr) throw new Error('Hey programmer, initialize your arrays!');
// ^ bad practice to throw exceptions in listeners, but if you get one, you've coded something wrongly.
for (var m:int=bullets_arr.length-1;m>=0;m--) {
var bm:Bullet=bullets_arr[m]; // TODO fix type
// the local variable is a cleaner and faster approach
bm.y-=20;
for (var n:int=Game.level1.enemies_arr.length-1;n>=0;n--) {
if (!bm) break; // bullet was destroyed, why checking more enemies vs that?
if (Game.level1.enemies_arr[n].hitTestObject(bm)) {
bm.parent.removeChild(bm);
bullets_arr.splice(m,1); // splice is done by index, not by object
bm=null; // oops, missed this. The bullet hit something and is now lost
// so we null the local var, so we can break out the loop.
Game.level1.enemies_arr[n].Damage(10, Game.level1.enemies_arr[n]);
}
}
}
// rest of your code follows here
}
I finally found the problem, it was very stupid of me :
I just mistyped the Die function in the Enemy class :
I have written :splice(Game.level1.enemies_arr.indexOf(enemyHit,1)) instead of splice(Game.level1.enemies_arr.indexOf(enemyHit),1)
Anyway I learnt a lot of think by trying to fix this error.
Thanks