I am currently learning swift and am experimenting with data structures. In may code I have certain routines with a name(String) and several tasks(Array of Strings). These values are in a structure.
So I am trying to add another value to the array after it has been initialized. My code is actually working, however I really think it very weird and odd and DO NOT think, that it is the way it should be done.
var routineMgr: routineManager = routineManager();
struct routine{
var name = "Name";
var tasks = [String]();
}
class routineManager: NSObject {
var routines = [routine]();
func addTask(name: String, desc: String){
//init routines with name and an array with certain values, here "Hallo" & "Moin"
routines.append(routine(name: name, tasks: ["Hallo","Moin"]));
//so i just put this part here to make the example shorter, but it would be in ad different function to make more sense
//adding a new value ("Salut") to the tasks array in the first routine
//getting current array
var tempArray = routines[0].tasks;
//appending new value to current value
tempArray.append("Salut");
//replacing old routine with a copy (same name), but the new array (with the appended salut)
routines[0] = routine(name: routines[0].name, tasks: tempArray);
}
}
I have tried some (to me) "more correct" ways, like:
routines[0].tasks.append("Salut");
But I always got tons of errors, which I also did not understand.
So my question now: How is it actually done correctly? And why does the second way not work?
Your help and advice is really appreciated!
You can create a function to append the values in the struct (that is what I would do). You can even use it to validade values or anything else you need to do before append, it can also return a boolean to let your code know if the value was successfully appended or not
var routineMgr: routineManager = routineManager();
struct routine{
var name = "Name";
var tasks = [String]();
mutating func addTask(task: String){
tasks.append(task)
}
}
class routineManager: NSObject {
var routines = [routine]();
func addTask(name: String, desc: String){
routines.append(routine(name: name, tasks: ["Hallo","Moin"]));
routines[0].addTask("Salut")
}
}
I hope that helps
Related
I have text file which contains 18000 lines which have cities names. Each line has city name, state, latitude, longitude etc. Below is the function which does that, if i don't implement string.components(separtedBy: ", ") loading function is pretty fast but with it implemented it takes time which makes my UI freeze. What is the right way of doing it? Is string.components(separtedBy: ", ") that costly?
I profiled the app, this line is taking string.components(separtedBy: ", ") 1.45s out of 2.09s in whole function.
func readCitiesFromCountry(country: String) -> [String] {
var cityArray: [String] = []
var flag = true
var returnedCitiesList: [String] = []
if let path = Bundle.main.path(forResource: country, ofType: "txt") {
guard let streamReader = StreamReader(path: path) else {fatalError()}
defer {
streamReader.close()
}
while flag {
if let nextLine = streamReader.nextLine() {
cityArray = nextLine.components(separatedBy: ",") // this is the line taking a lot of time, without this function runs pretty fast
if (country == "USA") {
returnedCitiesList.append("\(cityArray[0]) , \(cityArray[1]) , \(cityArray[2])")
} else {
returnedCitiesList.append("\(cityArray[0]) , \(cityArray[1])")
}
//returnedCitiesList.append(nextLine)
} else {
flag = false
}
}
} else {
fatalError()
}
return returnedCitiesList
}
StreamReader used in the code can be found here. It helps to read file line by line
Read a file/URL line-by-line in Swift
This question is not about how to split the string into array Split a String into an array in Swift? , rather why splitting is taking more time in the given function.
NSString.components(separatedBy:) returns a [String], which requires that all of the pieces' content be copied, from the original string, and pasted into new-ly allocated stringss. This slows things down.
You could address the symptoms (UI freezing) by putting this work on a background thread, but that just sweeps the problem under the wrong (the inefficient copying is still there), and complicates things (async code is never fun).
Instead, you should consider using String.split(separator:maxSplits:omittingEmptySubsequences:), which returns [Substring]. Each Substring is just a view into the original string's memory, which stores the relevant range so that you only see that portion of the String which is modeled by the Substring. The only memory allocation happening here is for the array.
Hopefully that should be enough to speed your code up to acceptable levels. If not, you should combine both solutions, and use split off-thread.
I am learning how to build apps and working with Swift for this project.
I had a buddy help me pull data in from a website and it looks like he created classes with variables and mapped them to certain extensions (IE "Username") so when I call the variable data such as profile I would call it. The below uses luck_30 able to store "Stats.luck_30"
luck_30.text = profile.luck_30
So inside one of my variables that is in this "Profile" class is setup into an array. I can pull the array out of the class, but I can't seem to do for while statement replacing the [#] with a variable from the for command.
func aliveWorkers(profile: Profile) -> NSNumber{
var myworkers : Array = profile.workers!
//this test works and returns the proper value
var testworker: NSNumber = myworkers[0].alive!
println("The satus of the test worker is " + testworker.description)
/* This code is giving error "Could not find member alive" it does not ifor var
for ifor in myworkers{
var thisworker: NSNumber = myworkers[ifor].alive! as NSNumber
}
*/
return 42
}
Your variable ifor is not a counter, it is an actual object. You could do something like this:
for worker in myWorkers {
let workerIsAlive = worker.alive!
}
Alternatively, if you need the index,
for i in 0 ..< myWorkers.count {
let worker = myWorkers[i]
let workerIsAlive = worker.alive!
}
If you need both:
for (i, worker) in enumerate(myWorkers) {
let workerIsAlive = worker.alive!
}
And as a matter of style, I would stay away from NSNumber and use Int or Bool or whatever the data actually is. Also, it looks like the alive variable should not be optional, as you're unwrapping it everywhere. To avoid "mysterious" crashes later, you may want to think about making it a non-optional type.
when using a for in loop, your loop variable isn't an index, its the objects you're looping through. so..
func aliveWorkers() {
var myworkers = [1, 2, 3]
//this test works and returns the proper value
let testworker = myworkers[0]
print("The satus of the test worker is \(testworker)")
for ifor in myworkers {
print(ifor)
}
}
Notice a few things... you don't need to use + to concatenate those strings. you can just use string interpolation. \(variable) inserts the value of variable in the string.
Try to use let instead of var when you don't change the variable. You don't need to explicitly define type on variables either.
i use the following function to retrieve a random person from an array:
func getRandomPerson() -> String{
if(personArray.isEmpty){
return ""
} else {
var tempArray: [String] = []
for person in personArray{
tempArray += [person.getName()]
}
var unsignedArrayCount = UInt32(tempArray.count)
var unsignedRandomNumber = arc4random_uniform(unsignedArrayCount)
var randomNumber = Int(unsignedRandomNumber)
if tempArray.isEmpty {
return ""
} else {
return tempArray[randomNumber]
}
}
}
I would like to use this function inside an array of strings, Like this:
var theDares: [String] = ["Dare1 \(getRandomPerson())", "Dare2", "Dare3", "Dare4", "Dare5"]
But when i use the functions, it only runs the function once. Can you make the function run everytime you use the "Dare1" in this instance.
Thanks in advance
I think you are asking if you can set up your array so every time you fetch the object at index 0, it re-builds the value there.
The short answer is no. Your code is creating an array of strings, and the item at index 0 is built ONCE using a function call.
However, it is possible to make a custom class implement the subscript operator. You could create a custom object that looks like an array and allows you to index into it using an Int index. In response to the index operator you could run custom code that built and returned a random string.
Since it sounds like you're a beginning programmer creating a custom class the implements the subscript operator might be beyond your current abilities however.
Try like this:
let personArray = ["John", "Steve", "Tim"]
var randomPerson: String {
return personArray.isEmpty ? "" : personArray[Int(arc4random_uniform(UInt32(personArray.count)))]
}
println(randomPerson) // "Steve"
I'm attempting to customize the "Page-Based Application" template and am new to Swift (and all programming for that matter). In my ModelController.swift I've created a 2D array to use as the primary datasource.
However, when I go to print it or use it as label.text it is including the parenthesis. How do I get just the strings of the array element I'm calling for?
class ModelController: NSObject, UIPageViewControllerDataSource {
var pageData: NSArray = [[String]]()
override init() {
super.init()
// Create the data model.
pageData = [["right", "wrong"], ["left", "right"]]
println(pageData[1]) //For
}
I'm not sure what else from this file is relevant but here's another bit.
func indexOfViewController(viewController: DataViewController) -> Int {
// Return the index of the given data view controller.
// For simplicity, this implementation uses a static array of model objects and the view controller stores the model object; you can therefore use the model object to identify the index.
if let dataObject: AnyObject = viewController.dataObject {
return self.pageData.indexOfObject(dataObject)
} else {
return NSNotFound
}
}
If you just want left, right
println("\(pageData[1][0]), \(pageData[1][1])")
If you literally want "left, right" with the double quotes included it's
println("\"\(pageData[1][0]), \(pageData[1][1])\"")
The reason you got the results you did is because pageData[1] isn't a String it's an NSArray. Because NSArray conforms to the Printable protocol it supplies its .description when used in println.
Let's say I have an array, each item in the array has a corresponding library item.
I'd like to do something like :
var rando = Math.round(Math.random()*3)
var myArray = new Array ["ball", "wall", "fall"]
var i:myArray[rando] = myArray[rando] new myArray[rando]()
addChild(i)
But, this doesn't work. What's the secret?
Thank You,
Victor Hugo
Surprised no one mentioned getDefinitionByName() here.
Here's some complete code to get your example working:
var myArray = ["ball", "wall", "fall"];
/**
* Creates a random instance based on an input array containing class names as Strings.
* #param The input array containing aforementioned Strings.
* #return The newly created instance.
*/
function createRandom(typeArray:Array):*
{
// Select random String from typeArray.
var selection:String = typeArray[ int(Math.random() * typeArray.length) ];
// Create instance of relevant class.
var Type:Class = getDefinitionByName(selection) as Class;
// Return created instance.
return new Type();
}
// Randomly create and add instance.
var instance:DisplayObject = createRandom(myArray);
addChild(instance);
Ok so there are a bunch of problems with this.
A large one being var i:myArray[rando] = myArray[rando] new myArray[rando]() not really too sure what you're trying to do here.
Anyway I'm going to assume ball, wall and fall are instance names of MovieClips you have in your library. I think you're going to want something like this
var rando:int = Math.floor(Math.random()*3); //As the comments point out this should give you a random
//int between 0 and 2, arrays are 0 indexed so this is what we want if we have 3 items
Now for your array, you're current putting strings in there. Flash has no idea what "ball", etc are.
Try something like this
var myArray:Array = new Array [new ball(), new wall(), new fall()]; //this creates a new instance of your library object and stores it in your array
Now to add one of these to your stage:
addChild(myArray[rando]); //this uses the random number to pull one of the items out of your array
What you're trying to do with var i:myArray[rando] doesn't really make sense. There is no type of myArray[rando] this slot should be holding a MovieClip
If you only have a few choices, it's easier to use a switch-case.
switch (rando) {
case 0:
i = new ball();
break;
case 1:
i = new wall();
break;
case 2:
i = new fall();
break;
}
addChild(i);
I suggest you define the variable i as a MovieClip, in which case it can be instantiated as both ball, wall, fall.
Given that ball, wall and fall are in the library exported to actionscript.
Just guessing off your limited information but give this a shot.
private function myFunction():void{
var rando = Math.round(Math.random()*3);
var myArray= new Array ["ball", "wall", "fall"];
}
private function generateItem(item:String):void{
switch(item){
case "ball" : generateBall(); break;
case "wall" : generateWall(); break;
case "fall" : generateFall(); break;
}
private function generateBall():void{
//code to generate ball
addChild(ball);
}
private function generateFall():void{
//code to generate fall
addChild(fall);
}
private function generateWall():void{
//code to generate wall
addChild(wall);
}
Change your arrary line to:
var myArray = new Array [ball, wall, fall];
This should work. :)
Marty Wallace gets big praise for steering me down the path of getDefinitionByName(). The example he posted was good, but this example does exactly what I was going for.
http://www.emanueleferonato.com/2011/03/31/understanding-as3-getdefinitionbyname-for-all-eval-maniacs/