Add value to empty Swift array

Question

I cannot figure out how to add values to an empty array in Swift. I have tried started with empty array in two different ways:

var emptyArray : Int[]?
emptyArray = Int[]()

and

var emptyArray = []

(by the way, what is the difference with these two ways of creating empty arrays?)

I have tried to add an integer to the array with emptyArray.append(1), emptyArray += [1] but none works nor it is in the guide book (or maybe, it is hidden some where that I couldn't figure out). Both of these work if there is one or more values in it and this is driving me crazy! Please let me know how to if you know how to do it. Thank you!

The difference: #1 creates a generic array that will contain Int's and only Int's. #2 creates a non-generic array that can contain items of any class. — Jean Le Moignan
– Jean Le Moignan, Commented Jun 15, 2014 at 12:47
Thank you, can you please tell me why when I create an empty array using #1, neither emptyArray.append(1) nor emptyArray += [1] work? — Fried Rice
– Fried Rice, Commented Jun 15, 2014 at 14:16

juniperi · Accepted Answer · 2014-06-15 12:09:14Z

15

First, create empty Int array:

var emptyArray : Int[] = []

or:

var emptyArray = Int[]()

Add number to that array (two ways):

emptyArray += [1]
emptyArray.append(2)

Array now contains [1, 2]

edited Jun 15, 2014 at 12:09

answered Jun 15, 2014 at 12:02

juniperi

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4 Comments

frankzk Over a year ago

Whats the difference between "+=" and "append"?

Suisse Over a year ago

@frankzk it's the same.

mfaani Over a year ago

@frankzk (1/2) Functionality wise they are identical. But I don't believe they are 100% the same. I believe append is better/faster. Why? Because the + operator is overloaded. Meaning every time the compiler sees + it has to go through series of checks. Like first identify the left had side's type. Is it an Int or a String or Array or whatever? Then let's just make sure the right hand side also has the same type.

mfaani Over a year ago

(2/2) This extra type checking takes time. See stackoverflow.com/questions/29707622/… and stackoverflow.com/a/48916182/5175709 @Suisse

Unconquered82 · Accepted Answer · 2015-04-10 16:07:04Z

6

You need to first declare the empty array in Swift like this:

 var emptyArray = [Int]()

You can then append that array with whatever value/variable you so choose like this:

emptyArray.append(6)

just be sure you keep in mind that trying to append a type that mismatches your array declaration will give you a compile error. For example, trying to append a string would error since this array was declared using the Int type.

Playgrounds in XCode are an excellent resource for testing things like this.

edited Apr 10, 2015 at 16:07

answered Apr 10, 2015 at 15:49

Unconquered82

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Comments

Deepak Tagadiya · Accepted Answer · 2019-01-23 05:37:46Z

0

Swift

     var arrName = [String]()
     arrName = ["Deep", "Hemant", "Yash"]
     print("old array--> ", arrName)
     arrName.append("Jay")
     print("new array--> ", arrName)

Output:- old array--> ["Deep", "Hemant", "Yash"]

new array--> ["Deep", "Hemant", "Yash", "Jay"]

answered Jan 23, 2019 at 5:37

Deepak Tagadiya

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