I got a 2D array where I want to fetch data from the 2nd dimension based on the 1st, but I dont understand how to set it up in Swift 2 since the old for-loop function is deprecated.
Based on the name (Burt) I want to present the phone-No and Group.
myArray: [[String]] = [["Adam", "123456", "Group1"], ["Burt", "251436", "Group2"], ["Cesar", "918273", "Group3"], ["David", "552277", "Group4"]
For i in 0..myArray.count {
If myArray[i][0] == "Burt" {
phoneNoLabel.text = myArray[i][1]
GroupNoLabel.text = myArray[i][2]
}
}
This is how I solved it with the help of Tarun Seera.
let myArray = [["Adam", "123456", "Group1"], ["Burt", "251436", "Group2"], ["Cesar", "918273", "Group3"], ["David", "552277", "Group4"]]
var user: String = "Burt"
var phoneNo: String = ""
var groupNo: String = ""
for i in myArray {
if i[0] == user {
phoneNo = i[1]
groupNo = i[2]
}
}
You can also make entities (NSObject)array and use predicate to achieve the same thing and still if you want this form 2d array you can use below code
let myArray = [["Adam", "123456", "Group1"], ["Burt", "251436", "Group2"], ["Cesar", "918273", "Group3"], ["David", "552277", "Group4"]]
for i in myArray {
if i[0] == "Burt" {
print("Hurrey I am in.. my name is: \(i[0]) my Id is:\(i[1]) and my gourp is:\(i[2])")
}
}
for i in 0..<myArray.count {
if myArray[i][0] == "Burt" {
phoneNoLabel.text = myArray[i][1]
GroupNoLabel.text = myArray[i][2]
}
}
Use
..<
instead of just
..
Your problem is, that i is going from 0 to myArray.count - which is 4 .. that means your i is going 0,1,2,3,4 = you have 5 times i. Your array only has 4 "items".
for i in 1...myArray.count{
if myArray[i-1][0] == "Burt" {
phoneNoLabel.text = myArray[i-1][1]
GroupNoLabel.text = myArray[i-1][2]
}
}
or
for i in 0...myArray.count-1{
if myArray[i][0] == "Burt" {
phoneNoLabel.text = myArray[i][1]
GroupNoLabel.text = myArray[i][2]
}
}
should solve your problem.
As an alternative to explicit looping, you could use a functional programming approach
let searchForUser = "Burt"
let userInfo = Array(myArray
.flatMap{ $0.first == searchForUser ? $0.suffixFrom(1) : nil }
.flatten())
print(userInfo) // ["251436", "Group2"]
For you specific example, the user info you're after is readily obtainable from the userInfo array
phoneNoLabel.text = userInfo[0] // 251436
groupNoLabel.text = userInfo[1] // Group2
Note here that I've renamed GroupNoLabel variable (UILabel?) from the example in your question to groupNoLabel, as variables in Swift should, by convention, use camelCase names (and not CamelCase, as is used e.g. for types).
Related
I'm looking for the best method to compare a string value entered by the user and compare it to the proper Stage and Level value.
As of now I've made a lot of arrays like so
let Stage1Level1 = ["Phone","Computer,Television"]
let Stage1Level2 = ["Horse","Shoe"]
let Stage1Level3 = ["Milk"]
let Stage2Level1 = ["Snow","Sun"]
let Stage2Level2 = ["Smile","Cry","Water","Salt"]
let Stage2Level3 = ["Five"]
and so on...
So instead of making a long if statement checking for which Stage and Level the user entered I'm looking for the most efficient way of doing this.
Something like this:
var currentStage = 1
var currentLogo = 2
#IBAction func textFieldChanged(_ sender: Any) {
if textFieldChangedOut.text? == Stage(currentStage)Level(currentLogo){
print("Contains the value")
}
}
It's not really clear what these string are, but this is definitely the wrong data structure. I suspect you're looking for something like this, an array of stages that each contain an array of levels, which contain an array of strings.
struct Level {
var values: [String]
}
struct Stage {
var levels: [Level]
}
let stages = [
Stage(levels: [
Level(values: ["One", "Two"])
Level(values: ["Horse", "Shoe"]),
Level(values: ["One", "Two"]),
]),
Stage(levels: [
Level(values: ["Snow", "Sun"]),
Level(values: ["Smile", "Cry"]),
Level(values: ["Five", "Six"]),
]),
]
var currentStage = 1
var currentLogo = 2
// Remember that arrays are 0-indexed. If "currentStage" is 1-indexed
// you need to adjust it
let level = stages[currentStage - 1].levels[currentLogo - 1]
let words = level.values
if let text = textFieldChangedOut.text, words.contains(text) {
print("Contains the value")
}
What you're trying to do with dynamically computing the name of the variable is impossible in pure Swift. There are ways to achieve it by bridging to ObjC, but they're not the right way to attack this problem.
I would create a struct of stage, level and the strings and have an array of that struct
struct StageLevel {
let stage: Int
let level: Int
let words: [String]
}
let stageLevelArray: [StageLevel] =
[StageLevel(stage: 1, level: 1, words: ["Hello", "Hi"]),
StageLevel(stage: 1, level: 2, words: ["Red", "Blue", "Green"]),
StageLevel(stage: 2, level: 1, words: ["No", "Yes"])]
then you can filter out all elements for a chosen stage
let levels = stageLevelArray.filter( { $0.stage == 1} )
or filter out for a stage and a level
let selection = stageLevelArray.filter( { $0.stage == 1 && $0.level == 2 } )
or if you only want the levels or arrays
let levels = stageLevelArray.filter( { $0.stage == 1} ).map { $0.level}
let selection = stageLevelArray.filter( { $0.stage == 1 && $0.level == 2 } ).map { $0.words }
Maybe you can understand adding a dictionary to your current data.
let Stage1Level1 = ["Phone","Computer,Television"]
let Stage1Level2 = ["Horse","Shoe"]
let Stage1Level3 = ["Milk"]
let Stage2Level1 = ["Snow","Sun"]
let Stage2Level2 = ["Smile","Cry","Water","Salt"]
let Stage2Level3 = ["Five"]
var currentStage = 1
var currentLogo = 2
var stageDict : [String: [String]] = [:]
stageDict["Stage1Level1"] = Stage1Level1
stageDict["Stage1Level2"] = Stage1Level2
stageDict["Stage1Level3"] = Stage1Level3
stageDict["Stage2Level1"] = Stage2Level1
stageDict["Stage2Level2"] = Stage2Level2
stageDict["Stage2Level3"] = Stage2Level3
//You also can build by this way
[[Stage1Level1, Stage1Level2, Stage1Level3], [Stage2Level1, Stage2Level2,Stage2Level3]]
.enumerated().forEach{ stage in stage.element.enumerated().forEach{
stageDict["Stage\(stage.offset+1)Level\($0.offset+1)"] = $0.element
}
}
#IBAction func textFieldChanged(_ sender: Any) {
if stageDict["Stage\(currentStage)Level\(currentLogo)"]!.contains(textFieldChangedOut.text!) {
print("Contains the value")
}
}
I am currently using 2 arrays:
let letters:[Character] =
[" ","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","!","#","#","$","%","^","&","*","(",")","1","2","3","4","5","6","7","8","9","0","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","E","S","T","U","V","W","X","Y","Z"]
let cypher:[Character] = ["o","p","q","r","a","b","c","d","e","f","g","h","i","u","v","w","x","y","z","j","k","l","m","n","s","t","$","#","#","!","&","%","^","*","("," ",")","5","7","2","9","8","0","1","3","2","4","Q","W","E","R","T","Y","U","I","O","P","A","S","D","F","G","H","J","K","L","Z","X","C","V","B","N","M"]
Both 73 characters.
I am using this line of code to encode the inserted text:
var encode:[Character:Character] = [:]
for (index, letter) in letters.enumerated() { encode[letter] = cypher[index] }
let encodeStep1 = String(insertedText.characters.map({ encode[$0] ?? $0 }))
randomNumber = Int(arc4random_uniform(9) + 1)
var encodeStep2 = cypher.rotate(shift: randomNumber)
for (index, letter) in letters.enumerated() { encode[letter] = encodeStep2[index] }
let final = String(encodeStep1.characters.map({ encode[$0] ?? $0 }))
Decode:
var decode:[Character:Character] = [:]
let step1 = cypher.rotate(shift: (randomNumber))
for (index, letter) in step1.enumerated() { decode[letter] = letters[index] }
let step1Decoded = String(insertedEncryptedText.characters.map({ decode[$0] ?? $0 }))
for (index, letter) in cypher.enumerated() { decode[letter] = letters[index] }
let step2Decoded = String(step1Decoded.characters.map({ decode[$0] ?? $0 }))
Rotate function:
extension Array {
func rotate(shift:Int) -> Array {
var array = Array()
if (self.count > 0) {
array = self
if (shift > 0) {
for i in 1...shift {
array.append(array.remove(at: 0))
}
}
else if (shift < 0) {
for i in 1...abs(shift) {
array.insert(array.remove(at: array.count-1),at:0)
}
}
}
return array
}
}
For some very odd reason, number "3" is often shown as a number "9" when decoded. From what I have seen, the problem occurs at step2Decoded. I just can not figure out what I am doing wrong. This is however a part of the code, if I need to post more I can do that.
It's because you have a typo. Your cypher array has two "2"s in it, one at cypher[39] and another 6 indices further at cypher[45]. When you're decoding in the final step you're expecting decoded["2"] to map to the value "3" in the letters array, which it does, but it's getting overwritten when it hits the "2" again setting it to the value 6 indices further in the letters array which has a value of "9".
I assume you want to change that second "2" value in the letters array to "6" instead (since I noticed there was no "6" in there). That would solve your problem.
What woudl be a simple way to reduce a string like AAA:111;BBB:222;333;444;CCC:555 to a dictionary in Swift. I have the following code:
var str = "AAA:111;BBB:222;333;444;CCC:555"
var astr = str.componentsSeparatedByString(";").map { (element) -> [String:String] in
var elements = element.componentsSeparatedByString(":")
if elements.count < 2 {
elements.insert("N/A", atIndex: 0)
}
return [elements[0]:elements[1]]
}
The code above produces an Array of Dictionaries:
[["A": "111"], ["BBB": "222"], ["UKW": "333"], ["UKW": "444"], ["CCC": "555"]]
I want it to produce
["A": "111", "BBB": "222", "UKW": "333", "UKW": "444", "CCC": "555"]
but no mater what I try, since i call the map function on an Array it seems impossible to convert the nature of the map function's result.
NOTE: The dictionary in string format is described as either having KEY:VALUE; format or VALUE; format, in which case the mapping function will add the "N/A" as being the key of the unnamed value.
Any help on this matter is greatly appreciated.
Your map produces an array of dictionaries. When you want to combine them into 1, that's a perfect job for reduce:
func + <K,V>(lhs: Dictionary<K,V>, rhs: Dictionary<K,V>) -> Dictionary<K,V> {
var result = Dictionary<K,V>()
for (key, value) in lhs {
result[key] = value
}
for (key, value) in rhs {
result[key] = value
}
return result
}
var str = "AAA:111;BBB:222;333;444;CCC:555"
var astr = str
.componentsSeparatedByString(";")
.reduce([String: String]()) {
aggregate, element in
var elements = element.componentsSeparatedByString(":")
if elements.count < 2 {
elements.insert("N/A", atIndex: 0)
}
return aggregate + [elements[0]:elements[1]]
}
print(astr)
Swift has no default operator to "combine" two Dictionaries so you have to define one. Note that the + here is not commutative: dictA + dictB != dictB + dictA. If a key exist in both dictionaries, the value from the second dictionary will be used.
This is a work for reduce:
let str = "AAA:111;BBB:222;333;444;CCC:555"
let keyValueStrings = str.componentsSeparatedByString(";")
let dictionary = keyValueStrings.reduce([String: String]()) {
aggregate, element in
var newAggregate = aggregate
let elements = element.componentsSeparatedByString(":")
let key = elements[0]
// replace nil with the value you want to use if there is no value
let value = (elements.count > 1) ? elements[1] : nil
newAggregate[key] = value
return newAggregate
}
print(dictionary)
You can also make aggregate mutable directly:
let dictionary = keyValueStrings.reduce([String: String]()) {
(var aggregate: [String: String], element: String) -> [String: String] in
let elements = element.componentsSeparatedByString(":")
let key = elements[0]
// replace nil with the value you want to use if there is no value
let value = (elements.count > 1) ? elements[1] : nil
aggregate[key] = value
return aggregate
}
This is a functional approach, but you can achieve the same using a for iteration.
The reason this is happening is because map can only return arrays. If you are using this method to parse your string, then you need to convert it to a dictionary after.
var newDict = [String:String]()
for x in astr {
for (i, j) in x {
newDict[i] = j
}
}
The current issue with your code is that map function iterates over array containing [["key:value"],["key:value"]..] and you separate it again. But it returns ["key":"value"] which you then add to your array.
Instead you can add elements[0]:elements[1] directly to a locally kept variable which will fix your problem. Something like
finalVariable[elements[0]] = elements[1]
I am new to Swift. I have been doing Java programming. I have a scenario to code for in Swift.
The following code is in Java. I need to code in Swift for the following scenario
// With String array - strArr1
String strArr1[] = {"Some1","Some2"}
String strArr2[] = {"Somethingelse1","Somethingelse2"}
for( int i=0;i< strArr1.length;i++){
System.out.println(strArr1[i] + " - "+ strArr2[i]);
}
I have a couple of arrays in swift
var strArr1: [String] = ["Some1","Some2"]
var strArr2: [String] = ["Somethingelse1","Somethingelse2"]
for data in strArr1{
println(data)
}
for data in strArr2{
println(data)
}
// I need to loop over in single for loop based on index.
Could you please provide your help on the syntaxes for looping over based on index
You can use zip(), which creates
a sequence of pairs from the two given sequences:
let strArr1 = ["Some1", "Some2"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]
for (e1, e2) in zip(strArr1, strArr2) {
print("\(e1) - \(e2)")
}
The sequence enumerates only the "common elements" of the given sequences/arrays. If they have different length then the additional
elements of the longer array/sequence are simply ignored.
With Swift 5, you can use one of the 4 following Playground codes in order to solve your problem.
#1. Using zip(_:_:) function
In the simplest case, you can use zip(_:_:) to create a new sequence of pairs (tuple) of the elements of your initial arrays.
let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]
let sequence = zip(strArr1, strArr2)
for (el1, el2) in sequence {
print("\(el1) - \(el2)")
}
/*
prints:
Some1 - Somethingelse1
Some2 - Somethingelse2
*/
#2. Using Array's makeIterator() method and a while loop
It is also easy to loop over two arrays simultaneously with a simple while loop and iterators:
let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]
var iter1 = strArr1.makeIterator()
var iter2 = strArr2.makeIterator()
while let el1 = iter1.next(), let el2 = iter2.next() {
print("\(el1) - \(el2)")
}
/*
prints:
Some1 - Somethingelse1
Some2 - Somethingelse2
*/
#3. Using a custom type that conforms to IteratorProtocol
In some circumstances, you may want to create you own type that pairs the elements of your initials arrays. This is possible by making your type conform to IteratorProtocol. Note that by making your type also conform to Sequence protocol, you can use instances of it directly in a for loop:
struct TupleIterator: Sequence, IteratorProtocol {
private var firstIterator: IndexingIterator<[String]>
private var secondIterator: IndexingIterator<[String]>
init(firstArray: [String], secondArray: [String]) {
self.firstIterator = firstArray.makeIterator()
self.secondIterator = secondArray.makeIterator()
}
mutating func next() -> (String, String)? {
guard let el1 = firstIterator.next(), let el2 = secondIterator.next() else { return nil }
return (el1, el2)
}
}
let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]
let tupleSequence = TupleIterator(firstArray: strArr1, secondArray: strArr2)
for (el1, el2) in tupleSequence {
print("\(el1) - \(el2)")
}
/*
prints:
Some1 - Somethingelse1
Some2 - Somethingelse2
*/
#4. Using AnyIterator
As an alternative to the previous example, you can use AnyIterator. The following code shows a possible implementation of it inside an Array extension method:
extension Array {
func pairWithElements(of array: Array) -> AnyIterator<(Element, Element)> {
var iter1 = self.makeIterator()
var iter2 = array.makeIterator()
return AnyIterator({
guard let el1 = iter1.next(), let el2 = iter2.next() else { return nil }
return (el1, el2)
})
}
}
let strArr1 = ["Some1", "Some2", "Some3"]
let strArr2 = ["Somethingelse1", "Somethingelse2"]
let iterator = strArr1.pairWithElements(of: strArr2)
for (el1, el2) in iterator {
print("\(el1) - \(el2)")
}
/*
prints:
Some1 - Somethingelse1
Some2 - Somethingelse2
*/
Try This:
zip([0,2,4,6], [1,3,5,7]).forEach {
print($0,$1)
}
zip([0,2,4,6], [1,3,5,7]).forEach {
print($0.0,$0.1)
}
You could also enumerate over one array and used the index to look inside the second array:
Swift 1.2:
for (index, element) in enumerate(strArr1) {
println(element)
println(strArr2[index])
}
Swift 2:
for (index, element) in strArr1.enumerate() {
print(element)
print(strArr2[index])
}
Swift 3:
for (index, element) in strArr1.enumerated() {
print(element)
print(strArr2[index])
}
You could use Range if you still want to use for in.
var strArr1: [String] = ["Some1","Some2"]
var strArr2: [String] = ["Somethingelse1","Somethingelse2"]
for i in Range(start: 0, end: strArr1.count) {
println(strArr1[i] + " - " + strArr2[i])
}
for(var i = 0; i < strArr1.count ; i++)
{
println(strArr1[i] + strArr2[i])
}
That should do it. Never used swift before so make sure to test.
Updated to recent Swift syntax
for i in 0..< strArr1.count {
print(strArr1[i] + strArr2[i])
}
> Incase of unequal count
let array1 = ["some1","some2"]
let array2 = ["some1","some2","some3"]
var iterated = array1.makeIterator()
let finalArray = array2.map({
let itemValue = iterated.next()
return "\($0)\(itemValue != nil ? "-"+itemValue! : EmptyString)" })
// result : ["some1-some1","some2-some2","some3"]
I want to store structs inside an array, access and change the values of the struct in a for loop.
struct testing {
var value:Int
}
var test1 = testing(value: 6 )
test1.value = 2
// this works with no issue
var test2 = testing(value: 12 )
var testings = [ test1, test2 ]
for test in testings{
test.value = 3
// here I get the error:"Can not assign to 'value' in 'test'"
}
If I change the struct to class it works. Can anyone tell me how I can change the value of the struct.
Besides what said by #MikeS, remember that structs are value types. So in the for loop:
for test in testings {
a copy of an array element is assigned to the test variable. Any change you make on it is restricted to the test variable, without doing any actual change to the array elements. It works for classes because they are reference types, hence the reference and not the value is copied to the test variable.
The proper way to do that is by using a for by index:
for index in 0..<testings.count {
testings[index].value = 15
}
in this case you are accessing (and modifying) the actual struct element and not a copy of it.
Well I am going to update my answer for swift 3 compatibility.
When you are programming many you need to change some values of objects that are inside a collection. In this example we have an array of struct and given a condition we need to change the value of a specific object. This is a very common thing in any development day.
Instead of using an index to determine which object has to be modified I prefer to use an if condition, which IMHO is more common.
import Foundation
struct MyStruct: CustomDebugStringConvertible {
var myValue:Int
var debugDescription: String {
return "struct is \(myValue)"
}
}
let struct1 = MyStruct(myValue: 1)
let struct2 = MyStruct(myValue: 2)
let structArray = [struct1, struct2]
let newStructArray = structArray.map({ (myStruct) -> MyStruct in
// You can check anything like:
if myStruct.myValue == 1 {
var modified = myStruct
modified.myValue = 400
return modified
} else {
return myStruct
}
})
debugPrint(newStructArray)
Notice all the lets, this way of development is safer.
The classes are reference types, it's not needed to make a copy in order to change a value, like it happens with structs. Using the same example with classes:
class MyClass: CustomDebugStringConvertible {
var myValue:Int
init(myValue: Int){
self.myValue = myValue
}
var debugDescription: String {
return "class is \(myValue)"
}
}
let class1 = MyClass(myValue: 1)
let class2 = MyClass(myValue: 2)
let classArray = [class1, class2]
let newClassArray = classArray.map({ (myClass) -> MyClass in
// You can check anything like:
if myClass.myValue == 1 {
myClass.myValue = 400
}
return myClass
})
debugPrint(newClassArray)
To simplify working with value types in arrays you could use following extension (Swift 3):
extension Array {
mutating func modifyForEach(_ body: (_ index: Index, _ element: inout Element) -> ()) {
for index in indices {
modifyElement(atIndex: index) { body(index, &$0) }
}
}
mutating func modifyElement(atIndex index: Index, _ modifyElement: (_ element: inout Element) -> ()) {
var element = self[index]
modifyElement(&element)
self[index] = element
}
}
Example usage:
testings.modifyElement(atIndex: 0) { $0.value = 99 }
testings.modifyForEach { $1.value *= 2 }
testings.modifyForEach { $1.value = $0 }
How to change Array of Structs
for every element:
itemsArray.indices.forEach { itemsArray[$0].someValue = newValue }
for specific element:
itemsArray.indices.filter { itemsArray[$0].propertyToCompare == true }
.forEach { itemsArray[$0].someValue = newValue }
You have enough of good answers. I'll just tackle the question from a more generic angle.
As another example to better understand value types and what it means they get copied:
struct Item {
var value:Int
}
func change (item: Item, with value: Int){
item.value = value // cannot assign to property: 'item' is a 'let' constant
}
That is because item is copied, when it comes in, it is immutable — as a convenience.
Had you made Item a class type then you were able to change its value.
var item2 = item1 // mutable COPY created
item2.value = 10
print(item2.value) // 10
print(item1.value) // 5
This is very tricky answer. I think, You should not do like this:
struct testing {
var value:Int
}
var test1 = testing(value: 6)
var test2 = testing(value: 12)
var ary = [UnsafeMutablePointer<testing>].convertFromArrayLiteral(&test1, &test2)
for p in ary {
p.memory.value = 3
}
if test1.value == test2.value {
println("value: \(test1.value)")
}
For Xcode 6.1, array initialization will be
var ary = [UnsafeMutablePointer<testing>](arrayLiteral: &test1, &test2)
It is possible to use the map function to get this effect - essentially creating a new array
itemsArray = itemsArray.map {
var card = $0
card.isDefault = aCard.token == token
return card
}
I ended up recreating a new array of struct see the example below.
func updateDefaultCreditCard(token: String) {
var updatedArray: [CreditCard] = []
for aCard in self.creditcards {
var card = aCard
card.isDefault = aCard.token == token
updatedArray.append(card)
}
self.creditcards = updatedArray
}
I tried Antonio's answer which seemed quite logical but to my surprise it does not work. Exploring this further I tried the following:
struct testing {
var value:Int
}
var test1 = testing(value: 6 )
var test2 = testing(value: 12 )
var testings = [ test1, test2 ]
var test1b = testings[0]
test1b.value = 13
// I would assume this is same as test1, but it is not test1.value is still 6
// even trying
testings[0].value = 23
// still the value of test1 did not change.
// so I think the only way is to change the whole of test1
test1 = test1b