My question is this with an example from the parse docs:
You have in parse the column with all kind of types, like string, array, etc.
Now I have the following kind of code:
var gameScore = PFObject(className:"GameScore")
gameScore["score"] = 1337
gameScore["playerName"] = "Sean Plott"
gameScore.saveInBackgroundWithBlock {
(success: Bool, error: NSError?) -> Void in
if (success) {
// The object has been saved.
} else {
// There was a problem, check error.description
}
}
Ok now I want to save another score behind the first score: 1337.
So when I retrieve from parse it will look like this: Sean: 1337, 1207.
Or something like that when I retrieve the name and scores. I have in parse it already set to be an array.
So my question is: How do I add a string to an array in parse.
Thank you beforehand.
You need "score" to be an Array in your DB. Then in your code, you do this:
gameScore.addObject([1337], forKey:"score")
Related
I'm learning Swift as I go here, so apologies if this is a silly question.
I'm looking to use the output of one function (String) to determine an input into a different function (Array).
The first function output (String) is then combined with another String to form the name of an already defined Array, which i'd like to use as input to second function. However, despite having the same name, the String is not seen as an array.
I've skipped some of the code, but relevant section below.
// Defined array
let rushProb = [0,11,19,64,78,89,96,98,99,100]
// Define probability and outcome function - PlayType
func findPlay(prob: [Int], outcome: [String]) -> String {
if let index = prob.firstIndex(where: { $0 > Int.random(in: 1...100) }) {
return outcome[index]
}
else {
return "na"
}
}
// This is successfully output as "rush"
let playSel = findPlay(prob: scen1Prob, outcome: scenPlay)
// This then creates "rushProb"
let playSelProb = playSel+"Prob"
// I want this to ultimately be findYards(prob: rushProb)
findYards(prob: playSelProb)
Well, you could use a dictionary where the key replaces your array name, and the value is the array. Then, you'd use the name you create to look up the array value in the dictionary:
let arrays = ["rushProb": [0,11,19,64,78,89,96,98,99,100],
"fooProb" : [0,15,29,44,68,78,86,92,94,100]]
// This is successfully output as "rush"
let playSel = findPlay(prob: scen1Prob, outcome: scenPlay)
// This then creates "rushProb"
let playSelProb = playSel+"Prob"
// look up the array that corresponds to "rushProb"
if let array = arrays[playSelProb] {
findYards(prob: array)
}
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
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 read into myArray (native Swift) from a file containing a few thousand lines of plain text..
myData = String.stringWithContentsOfFile(myPath, encoding: NSUTF8StringEncoding, error: nil)
var myArray = myData.componentsSeparatedByString("\n")
I change some of the text in myArray (no point pasting any of this code).
Now I want to write the updated contents of myArray to a new file.
I've tried this ..
let myArray2 = myArray as NSArray
myArray2.writeToFile(myPath, atomically: false)
but the file content is then in the plist format.
Is there any way to write an array of text strings to a file (or loop through an array and append each array item to a file) in Swift (or bridged Swift)?
As drewag points out in the accepted post, you can build a string from the array and then use the writeToFile method on the string.
However, you can simply use Swift's Array.joinWithSeparator to accomplish the same with less code and likely better performance.
For example:
// swift 2.0
let array = [ "hello", "goodbye" ]
let joined = array.joinWithSeparator("\n")
do {
try joined.writeToFile(saveToPath, atomically: true, encoding: NSUTF8StringEncoding)
} catch {
// handle error
}
// swift 1.x
let array = [ "hello", "goodbye" ]
let joined = "\n".join(array)
joined.writeToFile(...)
With Swift 5 and I guess with Swift 4 you can use code snippet which works fine to me.
let array = ["hello", "world"]
let joinedStrings = array.joined(separator: "\n")
do {
try joinedStrings.write(toFile: outputURL.path, atomically: true, encoding: .utf8)
} catch let error {
// handle error
print("Error on writing strings to file: \(error)")
}
You need to reduce your array back down to a string:
var output = reduce(array, "") { (existing, toAppend) in
if existing.isEmpty {
return toAppend
}
else {
return "\(existing)\n\(toAppend)"
}
}
output.writeToFile(...)
The reduce method takes a collection and merges it all into a single instance. It takes an initial instance and closure to merge all elements of the collection into that original instance.
My example takes an empty string as its initial instance. The closure then checks if the existing output is empty. If it is, it only has to return the text to append, otherwise, it uses String Interpolation to return the existing output and the new element with a newline in between.
Using various syntactic sugar features from Swift, the whole reduction can be reduced to:
var output = reduce(array, "") { $0.isEmpty ? $1 : "\($0)\n\($1)" }
Swift offers numerous ways to loop through an array. You can loop through the strings and print to a text file one by one. Something like so:
for theString in myArray {
theString.writeToFile(myPath, atomically: false, encoding: NSUTF8StringEncoding, error: nil);
}
There is something wrong when I unmarshal the json array.
How do I correct it ? the code is:http://play.golang.org/p/AtU9q8Hlye
package main
import (
"encoding/json"
"fmt"
)
type Server struct {
ServerName string
ServerIP string
}
type Serverslice struct {
Name string
Servers []Server
}
func main() {
var s []Serverslice
str := `{"name":"dxh","servers":[{"serverName":"VPN0","serverIP":"127.0.0.1"},{"serverName":"Beijing_VPN","serverIP":"127.0.0.2"}],
"name":"dxh1,"servers":[{"serverName":"VPN1","serverIP":"127.0.0.1"},{"serverName":"Beijing_VPN","serverIP":"127.0.0.2"}]}`
json.Unmarshal([]byte(str), &s) //the wrong line.....................
fmt.Println(len(s))
}
First of all, you're ignoring the error return value from json.Unmarshal. You probably want something like:
if err := json.Unmarshal([]byte(str), &s); err != nil {
log.Fatalln(err)
}
With that change, we can see that your JSON data isn't valid: invalid character 's' after object key:value pair. There is a missing quote at the end of "dxh1 on the second line.
Fixing that error and rerunning the program you'll get a different error: json: cannot unmarshal object into Go value of type []main.Serverslice. There are two possible problems here:
You meant to decode into an object. In this case, just declare s as a Serverslice. Here is a version of your program that makes that change: http://play.golang.org/p/zgyr_vnn-_
Your JSON is supposed to be an array (possible, since it seems to have duplicate keys). Here's an updated version with the JSON changed to provide an array: http://play.golang.org/p/Wl6kUaivEm