I've designed my program so that each time the user touches the screen, the sprite's image and position changes. I want to be able to make an array of SKSpriteNodes. I've seen a similar post, but they used a for-in loop. Is it possible to create a SKSpriteNode at initialization?
GameScene: SKScene {
// make an array of images that you will possibly change in the future
// calls the image
let dad = SKSpriteNode(imageNamed: "dad0")
var imageName = "dad"
let moveLeft = SKAction.moveByX(-10, y:0 , duration: 0.01)
...assuming that I already placed dad sprite node onto screen...
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
// when index is zero, sprite is dad0.
// Change image to dad1 (lifted leg), don't change position
if index == 0{
index += 1 //image names are dad0, dad1
imageName += "\(index)"
print(imageName)
dad.texture = SKTexture(imageNamed:imageName)
}
else{
index += 1
imageName += "\(index)"
print(imageName)
dad.texture = SKTexture(imageNamed:imageName)
//moves dad
dad.runAction(moveLeft) // moves image
index = 0
}
//change the image name back to dad
imageName = "dad"
}
}
An array of SKSpriteNode could be simply: [SKSpriteNode] (Array in swift composed by elements of SKSpriteNode type)
So , everytime you want to add a new SKSpriteNode you can do it with:
var arraySprites :[SKSpriteNode] = [SKSpriteNode]()
let dad : SKSpriteNode!
dad = SKSpriteNode(imageNamed: "dad0")
arraySprites.append(dad)
Related
I am new to coding in Swift. My goal is to build a variable containing the sum of a number of custom class variables.
To speak in clear terms:
I have a custom class called "Entry" which has the Double variable "sum", e.g. 50.00.
I am using a ViewController to let the user create a new entry with text field inputs, inter alia a sum of the new entry. This new entry element is then appended to an array of type Entry when the relevant button is pressed.
#IBAction func addEntry(_ sender: UIButton){
// take user input
let name = nameTextField.text ?? ""
let sum = Double(sumTextField.text!) ?? 0.0
let category = selectedCategory
// save user input in new entry
let newEntry = Entry(name: name, sum: sum, category: category)
entries.append(newEntry)
saveEntries()
os_log("Saved new entry successfully.", log: OSLog.default, type: .debug)
In another ViewController, I want to access the array "entries" and build the sum of all sum variables of all Entry elements, e.g. sum of Entry 1 + sum of Entry 2 + sum of Entry 3
My current attempt in coding is as follows:
var entriesDatabase = [Entry]()
//extract sum of entries and build sumOfEntries
var sumArray = [Double]()
for entry in entriesDatabase {
sumArray.append(entry.sum)
}
sumOfEntries = sumArray.reduce(0, +)
The entries array from the first View Controller is saved by using the NSKeyedArchiver and loaded by NSKeyedUnarchiver.unarchiveObject(withFile:) in the second View Controller before calling the function above (which, I am aware, has been deprecated, but it works for my current purposes).
I used the print function to isolate the issue and as far as I can see, the sumOfEntries always remains 0.0, no matter how many Entry elements I create (which itself seems to work, though).
Has anyone a clue what I am doing wrong?
EDIT: The issue to me really seems to be that the calculation does not work rather than the passing of the data from one view to another. Somehow, the arrays always remain empty. The passage of the data works via saving it persistently on the drive and then loading it with the NSKeyedArchiver functions. For clarity see the following code:
/MARK: calculate and display balance
func calculate(){
//load data from user defaults
recurringCalculationValue = UserDefaults.standard.value(forKey: "recurringExpenses") ?? 0.0
monthlyIncomeCalculationValue = UserDefaults.standard.value(forKey: "monthlyIncome") ?? 0.0
//extract sum of entries and build sumOfEntries
var sumArray = [Double]()
for entry in entriesDatabase {
sumArray.append(entry.sum)
}
sumOfEntries = sumArray.reduce(0, +)
//cast the user defaults into Double
let mICV = monthlyIncomeCalculationValue as! Double
let rCV = recurringCalculationValue as! Double
//convert the Strings to Double! and calculate balance
balance = Double(mICV) - Double(rCV) - sumOfEntries
//display balance in sumLabel
sumLabel.text = "\(balance)"
//debugging
print("balance = \(balance)")
print("sumOfEntries = \(sumOfEntries)")
print("monthlyIncomeCalculationValue = \(monthlyIncomeCalculationValue)")
print("recurringCalculationValue = \(recurringCalculationValue)")
print("UserDefault monthlyIncome = \(String(describing: UserDefaults.standard.value(forKey: "monthlyIncome")))")
print("UserDefault recurringExpenses = \(String(describing: UserDefaults.standard.value(forKey: "recurringExpenses")))")
}
//this function is called when the ViewController is opened
#IBAction func unwindToThisViewController(segue: UIStoryboardSegue) {
//Load saved entries into entries array if entries were saved
let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
let url = NSURL(fileURLWithPath: path)
if let pathComponent = url.appendingPathComponent("entries") {
let filePath = pathComponent.path
let fileManager = FileManager.default
if fileManager.fileExists(atPath: filePath) {
print("File available.")
entriesDatabase = loadEntries()!
print("Database loaded.")
} else {
print("File not available.")
}
} else {
print("File path not available.")
}
calculate()
}
private func loadEntries() -> [Entry]? {
return NSKeyedUnarchiver.unarchiveObject(withFile: Entry.ArchiveURL.path) as? [Entry]
}
I hope, that makes my problem clearer and thanks again!
The way I see it, in var entriesDatabase = [Entry]() you create a new array for objects of type Entry, which is (of course) initially empty. Therefore, the sum of the values will be 0.
What you want is to cache the values, e.g. in your saveEntries()-Function. You may want to take a look at UserDefaults which stores information in a map-like matter.
I want a picture to move to the bottom. If I press a button the pic should move down by 1.
I added the picture and a button:
var corX = 0
var corY = 0
var runter: UIButton = UIButton.buttonWithType(UIButtonType.System) as UIButton
var image = UIImage(named: "panzerBlau.jpg");
var panzer = UIImageView(frame: CGRectMake(corX, corY, 30, 40)); //
override func viewDidLoad() {
super.viewDidLoad()
panzer.image = image; //
self.view.addSubview(panzer); //
runter.frame = CGRectMake(100, 30, 10 , 10)
runter.backgroundColor = UIColor.redColor()
view.addSubview(runter)
runter.addTarget(self, action: "fahren", forControlEvents:UIControlEvents.TouchUpInside)
}
At least I said in function "fahren" to move the picture down by 1.
func fahren(){
corY += 1
panzer.frame = CGRectMake(corX, corY, 30, 40) //
self.view.addSubview(panzer);
}
So my problem is: I get several errors with these corX and corY thing. Without them it works perfectly but than its like a single-use button. The errors are: ViewController.Type does not have a member named corX and ViewController.Type does not have a member names panzer Where I get the errors I made // to show in which lines.
PS: I use Xcode Beta5
Here's the complete code without anything else:
import UIKit
class ViewController: UIViewController {
var corX = 0
var corY = 0
var runter: UIButton = UIButton.buttonWithType(UIButtonType.System) as UIButton
var image = UIImage(named: "panzerBlau.jpg");
var panzer = UIImageView(frame: CGRectMake(corX, corY, 30, 40));
override func viewDidLoad() {
super.viewDidLoad()
panzer.image = image;
self.view.addSubview(panzer);
runter.frame = CGRectMake(100, 30, 10 , 10)
runter.backgroundColor = UIColor.redColor()
view.addSubview(runter)
runter.addTarget(self, action: "fahren", forControlEvents:UIControlEvents.TouchUpInside)
}
func fahren(){
corY += 100
panzer.frame = CGRectMake(corX, corY, 30, 40)
self.view.addSubview(panzer);
}
}
#MartinR has pointed out the major issue here:
var corX = 0
var corY = 0
var panzer = UIImageView(frame: CGRectMake(corX, corY, 30, 40))
The problem is that a Swift default initializer cannot refer to the value of another property, because at the time of initialization, the property doesn't exist yet (because the instance itself doesn't exist yet). Basically, in panzer's default initializer you are implicitly referring to self.corX and self.corY - but there is no self because self is exactly what we are in the middle of creating.
One workaround is to make the initializer lazy:
class ViewController: UIViewController {
var corX : CGFloat = 0
var corY : CGFloat = 0
lazy var panzer : UIImageView = UIImageView(frame: CGRectMake(self.corX, self.corY, 30, 40))
// ...
}
That's legal because panzer doesn't get initialized until later, when it is first referred to by your actual code. By that time, self and its properties exist.
Your dependent property needs to be:
lazy
Have an explicit : Type
Use self. to access other properties
Example:
let original = "foo"
// Good:
lazy var depend: String = self.original
// Error:
var noLazy: String = self.original // Error: Value of type '(NSObject) -> () -> URLData' has no member 'original'
lazy var noType = self.original // Error: Value of type '(NSObject) -> () -> URLData' has no member 'original'
lazy var noSelf: String = original // Error: Instance member 'original' cannot be used on type 'YourClass'
I'm addressing the title of the question:
Both lazy and computed properties help you deal with when the initial value for a property is not known until after the object is initialized. But there are some differences. I've highlighted the differences with bold.
If you simply need to initialize a variable after some other variable(s) is initialized then you should use lazy ie if the point is to simply add a delay (so all required properties get initialized before) then using lazy is the right way to go for it.
But if you need to constantly change a variable based on another, then you need a computed property that would work both ways:
if the computed property set then it sets the variables its related stored properties
if the stored properties are set (or are reset again) then it will trigger a change in then computed property.
if you change the lazy property's value it won't affect the storied properties that it was based on. see here
A good example for using a lazy property would be that once you have firstName & lastName then you would lazily instantiate a fullName and likely you would never change the firstName lastName of your object your fullName is a onetime only...
Or perhaps something that can only be done by lazy properties is that up until you don't access the property it won't ever get initialized, therefore this would decrease the initialization load of your class. Loading a heavy calculation.
Additionally using the lazy will signal to other developers: "Hey first go read about the other properties and understand what they are...then come to this lazy property...since the value of this is based on them + this is likely a heavy computation that shouldn't be accessed too early..."
As for computed property a good example would be if you set the temperature to Fahrenheit then you also want your celsius temperature to change its value...and if you set the celsius temperature then again you want to change your Fahrenheit value.
As a result computed property would add extra computation...and if your computation is very simple and isn't called too frequently then it's nothing to worry about but if it get's called too often or is very CPU-consuming then it might be better to think of other options...
//
// ViewController.swift
//
// Created by Shivank Agarwal on 19/05/18.
// Copyright © 2018 Shivank Agarwal. All rights reserved.
//
import UIKit
class ViewController: UIViewController {
var corX = 0
var corY = 0
var runter: UIButton = UIButton()
var image = UIImage(named: "panzerBlau.jpg")
var panzer = UIImageView()
override func viewDidLoad() {
super.viewDidLoad()
panzer.image = image;
self.view.addSubview(panzer);
panzer.frame = CGRect(x: CGFloat(corX), y: CGFloat(corY), width: 30, height: 40)
runter.backgroundColor = UIColor.red
view.addSubview(runter)
view.addSubview(panzer)
runter.addTarget(self, action: Selector(("fahren")), for:UIControlEvents.touchUpInside)
}
private func fahren(){
corY += 100
}
private func updatePanzerFrame(){
panzer.frame = CGRect(x: CGFloat(corX), y: CGFloat(corY), width: 30, height: 40)
}
}
Note: Do not add panzer imageView every time when user tap only add it on viewDidLoad()
I have a button which creates other buttons based on the class Clip seen below. Those newly created buttons are added to an array and stored in a plist.
class Clip: Encodable, Decodable {
var name: String = ""
var xCoordinate: Int = 100
var yCoordinate: Int = 300
// more parameter will be added later on e.g color, scale etc..
}
Each button can be moved around the view and the new x & y coordinates are stored in a plist.
#objc func handlePan(sender: UIPanGestureRecognizer){
let uIViewSelected = sender.view!
switch sender.state {
case .began, .changed :
moveViewWithPan(view: uIViewSelected, sender: sender)
break
case .ended:
//Finds the position when the button is no longer being dragged
let x = Int(uIViewSelected.center.x)
let y = Int(uIViewSelected.center.y)
//clipArray[0] need to be the corresponding clicked button e.g clipArray[2]
clipArray[0].xCoordinate = x
clipArray[0].yCoordinate = y
saveData()
break
default:
break
}
}
The above works only if I create one button. When more buttons are added, the above lines only change the first clip from the array. I need a way to update the value to the correct button clicked.
How can identify the array position of the click button as I am creating all them programmatically? At the moment I am placing at value 0 of the clipArray.
clipArray[0].xCoordinate = x
clipArray[0].yCoordinate = y
I am not even sure if using a plist is the best way to store the buttons in the first place.
Any help or documentation would be much appreciated.
Thanks
Following from dfd response, I added tags to each button which are created and it solved the issue for now.
let x = Int(uIViewSelected.center.x)
let y = Int(uIViewSelected.center.y)
//clipArray.append(clip)
var tagNo = uIViewSelected.tag
clipArray[tagNo].xCoordinate = x
clipArray[tagNo].yCoordinate = y
I'm kind of stuck on what I would assume is a simple solution and I just can't figure out what to do.
I'm basically creating an expenses application for iOS and I've gotten to the point where I need to add up all the total expenses from my UITableView list.
private var items:[Shoe] = []
private var appDelegate = UIApplication.shared.delegate as! AppDelegate
private var managedContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
// Start of calculating the gain or loss for the individual item
let buyDouble: Double? = Double(buyToSave)
let sellDouble: Double? = Double(sellToSave)
let feeDouble: Double? = Double(feeToSave)
let feeInt = 1-(feeDouble!/100)
let profit = (feeInt*sellDouble!) - buyDouble!
let profitNSNumb = profit as NSNumber
let profitString = currencyFormatter.string(from: profitNSNumb)
let shoe = Shoe(entity: Shoe.entity(), insertInto: self.managedContext)
shoe.name = nameToSave
shoe.buyPrice = buyToSave
shoe.sellPrice = sellToSave
shoe.size = sizeToSave
shoe.fee = feeToSave
shoe.profitLoss = profitString
shoe.quantity = Int16(shoeQuantity)
shoe.sum = shoe.sum + profit
// Save the data
self.appDelegate.saveContext()
// Reloads the UITableView
self.shoeList.reloadData()
self.viewDidLoad()
I believe my logic is correct right? Im not sure why I keep start at $0 every time I quit my application and open it back up again?
ex:
ITEM #.......EXPENSE
Item 1.......$100
Item 2.......$200
Item 3.......$50
Total Expense: $350
Then when I close the app and start it up again:
ITEM #.......EXPENSE
Item 1.......$100
Item 2.......$200
Item 3.......$50
Total Expense: $350 <---- I want it to start at $350 and not $0
You have to call .save() on context in order to save the changes you made (in this case created a new Shoe object).
Try saving it like this:
do {
try self.managedContext.save()
} catch {
print("Failed saving")
}
I've been looking for a little while on how to create a circle in Swift, but it seems quite complicated. I want to create a circle at run time, with a specified x and y, and width and height. I then want to add this circle to an array where I can create more circles and add to it.
How do I do this?
Edit: This is what I've tried so far:
var center : CGPoint = touchLocation
var myContext : CGContextRef = UIGraphicsGetCurrentContext()
let color : [CGFloat] = [0, 0, 1, 0.5]
CGContextSetStrokeColor (myContext, color);
CGContextStrokeEllipseInRect (myContext, CGRectMake(touchLocation.x, touchLocation.y, 20, 20));
touchLocation is the location of the users finger. This crashes on execution on this line:
var myContext : CGContextRef = UIGraphicsGetCurrentContext()
The error says "Unexpectedly found nil while unwrapping an Optional value
Also, this doesn't allow me to add the circle to an array, because I don't know what variable type it is.
There are many ways to draw a circle, here is a snippet that I have been hacking with:
func circleWithCenter(c:CGPoint, radius r:CGFloat,
strokeColor sc: UIColor = UIColor.blackColor(),
fillColor fc: UIColor = UIColor.clearColor()) -> CAShapeLayer {
var circle = CAShapeLayer()
circle.frame = CGRect(center:c, size:CGSize(width:2*r, height:2*r))
circle.path = UIBezierPath(ovalInRect:circle.bounds).CGPath
circle.fillColor = fc.CGColor
circle.strokeColor = sc.CGColor
circle.fillColor = fc == UIColor.clearColor() ? nil : fc.CGColor
return circle
}
Note that I extended CGRect (using Swift specific features) to add a initializer that takes a center, but that is not material to your question.
Your code is not "creating" a circle as an object, it is attempting to draw one in the graphics context. What you need to do is to create a bezier path object, draw into that and save the path in your array. Something like:
var circleArray = [CGMutablePathRef]()
// ...
let path: CGMutablePathRef = CGPathCreateMutable()
CGPathAddArc(path, nil, touchLocation.x, touchLocation.y, radius, 0, M_PI * 2, true)
circleArray += [path]
You then need to stroke the path(s) in your draw routine.