Suppose I have an array, for example:
var myArray = ["Steve", "Bill", "Linus", "Bret"]
And later I want to push/append an element to the end of said array, to get:
["Steve", "Bill", "Linus", "Bret", "Tim"]
What method should I use?
And what about the case where I want to add an element to the front of the array? Is there a constant time unshift?
As of Swift 3 / 4 / 5, this is done as follows.
To add a new element to the end of an Array.
anArray.append("This String")
To append a different Array to the end of your Array.
anArray += ["Moar", "Strings"]
anArray.append(contentsOf: ["Moar", "Strings"])
To insert a new element into your Array.
anArray.insert("This String", at: 0)
To insert the contents of a different Array into your Array.
anArray.insert(contentsOf: ["Moar", "Strings"], at: 0)
More information can be found in the "Collection Types" chapter of "The Swift Programming Language", starting on page 110.
You can also pass in a variable and/or object if you wanted to.
var str1:String = "John"
var str2:String = "Bob"
var myArray = ["Steve", "Bill", "Linus", "Bret"]
//add to the end of the array with append
myArray.append(str1)
myArray.append(str2)
To add them to the front:
//use 'insert' instead of append
myArray.insert(str1, atIndex:0)
myArray.insert(str2, atIndex:0)
//Swift 3
myArray.insert(str1, at: 0)
myArray.insert(str2, at: 0)
As others have already stated, you can no longer use '+=' as of xCode 6.1
To add to the end, use the += operator:
myArray += ["Craig"]
myArray += ["Jony", "Eddy"]
That operator is generally equivalent to the append(contentsOf:) method. (And in really old Swift versions, could append single elements, not just other collections of the same element type.)
There's also insert(_:at:) for inserting at any index.
If, say, you'd like a convenience function for inserting at the beginning, you could add it to the Array class with an extension.
Use += and + operators :
extension Array {
}
func += <V> (inout left: [V], right: V) {
left.append(right)
}
func + <V>(left: Array<V>, right: V) -> Array<V>
{
var map = Array<V>()
for (v) in left {
map.append(v)
}
map.append(right)
return map
}
then use :
var list = [AnyObject]()
list += "hello"
list += ["hello", "world!"]
var list2 = list + "anything"
The main benefit of
DequeoverArrayis that it supports efficient insertions and removals at both ends.
var names:Deque = ["Steve", "Bill", "Linus", "Bret"]
names.append("Tim")
names.prepend("John")
names.popFirst() // "John"
names.popLast() // "Tim"
Here is a small extension if you wish to insert at the beginning of the array without loosing the item at the first position
extension Array{
mutating func appendAtBeginning(newItem : Element){
let copy = self
self = []
self.append(newItem)
self.appendContentsOf(copy)
}
}
In Swift 4.1 and Xcode 9.4.1
We can add objects to Array basically in Two ways
let stringOne = "One"
let strigTwo = "Two"
let stringThree = "Three"
var array:[String] = []//If your array is string type
Type 1)
//To append elements at the end
array.append(stringOne)
array.append(stringThree)
Type 2)
//To add elements at specific index
array.insert(strigTwo, at: 1)
If you want to add two arrays
var array1 = [1,2,3,4,5]
let array2 = [6,7,8,9]
let array3 = array1+array2
print(array3)
array1.append(contentsOf: array2)
print(array1)
From page 143 of The Swift Programming Language:
You can add a new item to the end of an array by calling the array’s append method
Alternatively, add a new item to the end of an array with the addition assignment operator (+=)
Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. https://itun.es/us/jEUH0.l
To add to the solutions suggesting append, it's useful to know that this is an amortised constant time operation in many cases:
Complexity: Amortized O(1) unless self's storage is shared with another live array; O(count) if self does not wrap a bridged NSArray; otherwise the efficiency is unspecified.
I'm looking for a cons like operator for Swift. It should return a new immutable array with the element tacked on the end, in constant time, without changing the original array. I've not yet found a standard function that does this. I'll try to remember to report back if I find one!
You could use
Myarray.insert("Data #\(index)", atIndex: index)
If you want to append unique object, you can expand Array struct
extension Array where Element: Equatable {
mutating func appendUniqueObject(object: Generator.Element) {
if contains(object) == false {
append(object)
}
}
}
If the array is NSArray you can use the adding function to add any object at the end of the array, like this:
Swift 4.2
var myArray: NSArray = []
let firstElement: String = "First element"
let secondElement: String = "Second element"
// Process to add the elements to the array
myArray.adding(firstElement)
myArray.adding(secondElement)
Result:
print(myArray)
// ["First element", "Second element"]
That is a very simple way, regards!
In Swift 4.2: You can use
myArray.append("Tim") //To add "Tim" into array
or
myArray.insert("Tim", at: 0) //Change 0 with specific location
Example: students = ["Ben" , "Ivy" , "Jordell"]
1) To add single elements to the end of an array, use the append(_:)
students.append(\ "Maxime" )
2) Add multiple elements at the same time by passing another array or a sequence of any kind to the append(contentsOf:) method
students.append(contentsOf: ["Shakia" , "William"])
3) To add new elements in the middle of an array by using the insert(_:at:) method for single elements
students.insert("Liam" , at:2 )
4) Using insert(contentsOf:at:) to insert multiple elements from another collection or array literal
students.insert(['Tim','TIM' at: 2 )
Swift 5.3, I believe.
The normal array wasvar myArray = ["Steve", "Bill", "Linus", "Bret"]
and you want to add "Tim" to the array, then you can use myArray.insert("Tim", at=*index*)so if you want to add it at the back of the array, then you can use myArray.append("Tim", at: 3)
