CODEWITHSUNDEEP
iosarraysswift
Troy
Troy

Reputation: 21902

How do I convert a Swift Array to a String?

I know how to programmatically do it, but I'm sure there's a built-in way...

Every language I've used has some sort of default textual representation for a collection of objects that it will spit out when you try to concatenate the Array with a string, or pass it to a print() function, etc. Does Apple's Swift language have a built-in way of easily turning an Array into a String, or do we always have to be explicit when stringifying an array?

Upvotes: 450

Views: 389248

Answers (25)

Antonio
Antonio

Reputation: 72790

If the array contains strings, you can use the String's join method:

var array = ["1", "2", "3"]

let stringRepresentation = "-".join(array) // "1-2-3"

In Swift 2:

var array = ["1", "2", "3"]

let stringRepresentation = array.joinWithSeparator("-") // "1-2-3"

This can be useful if you want to use a specific separator (hyphen, blank, comma, etc).

Otherwise, you can simply use the description property, which returns a string representation of the array:

let stringRepresentation = [1, 2, 3].description // "[1, 2, 3]"

Hint: any object implementing the Printable protocol has a description property. If you adopt that protocol in your classes/structs, you make them print-friendly as well

In Swift 3

  • join becomes joined, example [nil, "1", "2"].flatMap({$0}).joined()
  • joinWithSeparator becomes joined(separator:) (only available to Array of Strings)

In Swift 4

var array = ["1", "2", "3"]
array.joined(separator:"-")

Upvotes: 835

Bilal Khan
Bilal Khan

Reputation: 1423

You can either use loops for getting this done. Or by using map.

By mapping:

let array = ["one" , "two" , "three"]
    
array.map({$0}).joined(seperator : ",")

so in separator you can modify the string.

Output-> ("one,two,three")

Upvotes: 6

krishnamurthy Rajendran
krishnamurthy Rajendran

Reputation: 99

if you want convert custom object array to string or comma separated string (csv) you can use

 var stringIds = (self.mylist.map{$0.id ?? 0}).map{String($0)}.joined(separator: ",")

credit to : urvish modi post: Convert an array of Ints to a comma separated string

Upvotes: 4

Dilan
Dilan

Reputation: 2698

you can use joined() to get a single String when you have array of struct also.

struct Person{
    let name:String
    let contact:String
}

You can easily produce string using map() & joined()

PersonList.map({"\($0.name) - \($0.contact)"}).joined(separator: " | ")

output:

Jhon - 123 | Mark - 456 | Ben - 789

Upvotes: 5

Rob
Rob

Reputation: 438307

Nowadays, in iOS 13+ and macOS 10.15+, we might use ListFormatter:

let formatter = ListFormatter()

let names = ["Moe", "Larry", "Curly"]
if let string = formatter.string(from: names) {
    print(string)
}

That will produce a nice, natural language string representation of the list. A US user will see:

Moe, Larry, and Curly

It will support any languages for which (a) your app has been localized; and (b) the user’s device is configured. For example, a German user with an app supporting German localization, would see:

Moe, Larry und Curly

Upvotes: 9

elhoucine ayoub
elhoucine ayoub

Reputation: 1009

use this when you want to convert list of struct type into string

struct MyStruct {
  var name : String
  var content : String
}

let myStructList = [MyStruct(name: "name1" , content: "content1") , MyStruct(name: "name2" , content: "content2")]

and covert your array like this way

let myString = myStructList.map({$0.name}).joined(separator: ",")

will produce ===> "name1,name2"

Upvotes: 0

Sentry.co
Sentry.co

Reputation: 5619

Since no one has mentioned reduce, here it is:

[0, 1, 1, 0].map {"\($0)"}.reduce("") { $0 + $1 } // "0110"

In the spirit of functional programming 🤖

Upvotes: 21

Tej Patel
Tej Patel

Reputation: 119

Try This:

let categories = dictData?.value(forKeyPath: "listing_subcategories_id") as! NSMutableArray
                        let tempArray = NSMutableArray()
                        for dc in categories
                        {
                            let dictD = dc as? NSMutableDictionary
                            tempArray.add(dictD?.object(forKey: "subcategories_name") as! String)
                        }
                        let joinedString = tempArray.componentsJoined(by: ",")

Upvotes: 0

john07
john07

Reputation: 560

for any Element type

extension Array {

    func joined(glue:()->Element)->[Element]{
        var result:[Element] = [];
        result.reserveCapacity(count * 2);
        let last = count - 1;
        for (ix,item) in enumerated() {
            result.append(item);
            guard ix < last else{ continue }
            result.append(glue());
        }
        return result;
    }
}

Upvotes: 0

Imanou Petit
Imanou Petit

Reputation: 92599

With Swift 5, according to your needs, you may choose one of the following Playground sample codes in order to solve your problem.

Turning an array of Characters into a String with no separator:

let characterArray: [Character] = ["J", "o", "h", "n"]
let string = String(characterArray)

print(string)
// prints "John"

Turning an array of Strings into a String with no separator:

let stringArray = ["Bob", "Dan", "Bryan"]
let string = stringArray.joined(separator: "")

print(string) // prints: "BobDanBryan"

Turning an array of Strings into a String with a separator between words:

let stringArray = ["Bob", "Dan", "Bryan"]
let string = stringArray.joined(separator: " ")

print(string) // prints: "Bob Dan Bryan"

Turning an array of Strings into a String with a separator between characters:

let stringArray = ["car", "bike", "boat"]
let characterArray = stringArray.flatMap { $0 }
let stringArray2 = characterArray.map { String($0) }
let string = stringArray2.joined(separator: ", ")

print(string) // prints: "c, a, r, b, i, k, e, b, o, a, t"

Turning an array of Floats into a String with a separator between numbers:

let floatArray = [12, 14.6, 35]
let stringArray = floatArray.map { String($0) }
let string = stringArray.joined(separator: "-")

print(string)
// prints "12.0-14.6-35.0"

Upvotes: 178

Oshitha Wimalasuriya
Oshitha Wimalasuriya

Reputation: 451

if you have string array list , then convert to Int 

let arrayList = list.map { Int($0)!} 
     arrayList.description

it will give you string value

Upvotes: 1

Alexey Chekanov
Alexey Chekanov

Reputation: 1117

A separator can be a bad idea for some languages like Hebrew or Japanese. Try this:

// Array of Strings
let array: [String] = ["red", "green", "blue"]
let arrayAsString: String = array.description
let stringAsData = arrayAsString.data(using: String.Encoding.utf16)
let arrayBack: [String] = try! JSONDecoder().decode([String].self, from: stringAsData!)

For other data types respectively:

// Set of Doubles
let set: Set<Double> = [1, 2.0, 3]
let setAsString: String = set.description
let setStringAsData = setAsString.data(using: String.Encoding.utf16)
let setBack: Set<Double> = try! JSONDecoder().decode(Set<Double>.self, from: setStringAsData!)

Upvotes: 2

Agent Smith
Agent Smith

Reputation: 2923

To change an array of Optional/Non-Optional Strings

//Array of optional Strings
let array : [String?] = ["1",nil,"2","3","4"]

//Separator String
let separator = ","

//flatMap skips the nil values and then joined combines the non nil elements with the separator
let joinedString = array.flatMap{ $0 }.joined(separator: separator)


//Use Compact map in case of **Swift 4**
    let joinedString = array.compactMap{ $0 }.joined(separator: separator

print(joinedString)

Here flatMap, compactMap skips the nil values in the array and appends the other values to give a joined string.

Upvotes: 9

dheeru
dheeru

Reputation: 329

If you question is something like this: tobeFormattedString = ["a", "b", "c"] Output = "abc"

String(tobeFormattedString)

Upvotes: -1

Sourav Chandra
Sourav Chandra

Reputation: 843

If you want to ditch empty strings in the array.

["Jet", "Fire"].filter { !$0.isEmpty }.joined(separator: "-")

If you want to filter nil values as well:

["Jet", nil, "", "Fire"].flatMap { $0 }.filter { !$0.isEmpty }.joined(separator: "-")

Upvotes: 3

garg
garg

Reputation: 2727

In Swift 4

let array:[String] = ["Apple", "Pear ","Orange"]

array.joined(separator: " ")

Upvotes: 16

Bartłomiej Semańczyk
Bartłomiej Semańczyk

Reputation: 61880

Create extension for an Array:

extension Array {

    var string: String? {

        do {

            let data = try JSONSerialization.data(withJSONObject: self, options: [.prettyPrinted])

            return String(data: data, encoding: .utf8)

        } catch {

            return nil
        }
    }
}

Upvotes: 1

Ty Daniels
Ty Daniels

Reputation: 99

FOR SWIFT 3: 

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    if textField == phoneField
    {
        let newString = NSString(string: textField.text!).replacingCharacters(in: range, with: string)
        let components = newString.components(separatedBy: NSCharacterSet.decimalDigits.inverted)

        let decimalString = NSString(string: components.joined(separator: ""))
        let length = decimalString.length
        let hasLeadingOne = length > 0 && decimalString.character(at: 0) == (1 as unichar)

        if length == 0 || (length > 10 && !hasLeadingOne) || length > 11
        {
            let newLength = NSString(string: textField.text!).length + (string as NSString).length - range.length as Int

            return (newLength > 10) ? false : true
        }
        var index = 0 as Int
        let formattedString = NSMutableString()

        if hasLeadingOne
        {
            formattedString.append("1 ")
            index += 1
        }
        if (length - index) > 3
        {
            let areaCode = decimalString.substring(with: NSMakeRange(index, 3))
            formattedString.appendFormat("(%@)", areaCode)
            index += 3
        }
        if length - index > 3
        {
            let prefix = decimalString.substring(with: NSMakeRange(index, 3))
            formattedString.appendFormat("%@-", prefix)
            index += 3
        }

        let remainder = decimalString.substring(from: index)
        formattedString.append(remainder)
        textField.text = formattedString as String
        return false
    }
    else
    {
        return true
    }
}

Upvotes: -1

hardikdevios
hardikdevios

Reputation: 1789

Swift 3 

["I Love","Swift"].joined(separator:" ") // previously joinWithSeparator(" ")

Upvotes: 23

Carlos Perez Perez
Carlos Perez Perez

Reputation: 407

In Swift 2.2 you may have to cast your array to NSArray to use componentsJoinedByString(",")

let stringWithCommas = (yourArray as NSArray).componentsJoinedByString(",")

Upvotes: 4

Maninderjit Singh
Maninderjit Singh

Reputation: 1456

let arrayTemp :[String] = ["Mani","Singh","iOS Developer"]
    let stringAfterCombining = arrayTemp.componentsJoinedByString(" ")
   print("Result will be >>>  \(stringAfterCombining)")

Result will be >>> Mani Singh iOS Developer

Upvotes: 3

123FLO321
123FLO321

Reputation: 862

You can print any object using the print function

or use \(name) to convert any object to a string.

Example:

let array = [1,2,3,4]

print(array) // prints "[1,2,3,4]"

let string = "\(array)" // string == "[1,2,3,4]"
print(string) // prints "[1,2,3,4]"

Upvotes: 1

Onur Var
Onur Var

Reputation: 1808

Mine works on NSMutableArray with componentsJoinedByString

var array = ["1", "2", "3"]
let stringRepresentation = array.componentsJoinedByString("-") // "1-2-3"

Upvotes: 4

Siva
Siva

Reputation: 391

Swift 2.0 Xcode 7.0 beta 6 onwards uses joinWithSeparator() instead of join():

var array = ["1", "2", "3"]
let stringRepresentation = array.joinWithSeparator("-") // "1-2-3"

joinWithSeparator is defined as an extension on SequenceType

extension SequenceType where Generator.Element == String {
    /// Interpose the `separator` between elements of `self`, then concatenate
    /// the result.  For example:
    ///
    ///     ["foo", "bar", "baz"].joinWithSeparator("-|-") // "foo-|-bar-|-baz"
    @warn_unused_result
    public func joinWithSeparator(separator: String) -> String
}

Upvotes: 49

Rob Napier
Rob Napier

Reputation: 299633

The Swift equivalent to what you're describing is string interpolation. If you're thinking about things like JavaScript doing "x" + array, the equivalent in Swift is "x\(array)".

As a general note, there is an important difference between string interpolation vs the Printable protocol. Only certain classes conform to Printable. Every class can be string interpolated somehow. That's helpful when writing generic functions. You don't have to limit yourself to Printable classes.

Upvotes: 1

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