Array by Example - Swift Programming Language

Overview

An ordered, random-access collection.
you use the Array type to hold elements of a single type, the array’s Element type. An array can store any kind of elements—from integers to strings to classes.

1. Creating and Initializing an Array

1.1 Creating an Array

Swift makes it easy to create arrays in your code using an array literal: simply surround a comma separated list of values with square brackets.
Without any other information, Swift creates an array that includes the specified values, automatically inferring the array’s Element type.

let oddNumbers = [1, 3, 5, 7, 9, 11, 13, 15]
print(oddNumbers)

//prints [1, 3, 5, 7, 9, 11, 13, 15]

let streets = ["Albemarle", "Brandywine", "Chesapeake"]
print(streets)

//prints ["Albemarle", "Brandywine", "Chesapeake"]

1.2 init(repeating:count:)

Creates a new array containing the specified number of a single, repeated value.

let fiveZs = Array(repeating: "Z", count: 5)
print(fiveZs)
//prints ["Z", "Z", "Z", "Z", "Z"]

1.3 init(_:)

Creates an array containing the elements of a sequence.

let numbers = Array(1...7)
print(numbers)

//prints [1, 2, 3, 4, 5, 6, 7]

1.4 init()

Creates a new, empty array.

var emptyArray = Array<Int>()
print(emptyArray.isEmpty)

// Prints "true"

emptyArray = []
print(emptyArray.isEmpty)

// Prints "true"

2. Inspecting an Array

2.1 isEmpty

A Boolean value indicating whether the collection is empty.

let horseName = "Silver"
if horseName.isEmpty {
    print("I've been through the desert on a horse with no name.")
} else {
    print("Hi ho, \(horseName)!")
}

// Prints "Hi ho, Silver!")

2.2 count

The number of elements in the array.

let numbers = Array(1...7)
print("Count of number array is \(numbers.count)")

//prints Count of number array is 7

2.3 capacity

The total number of elements that the array can contain without allocating new storage.

let numbers = Array(1...7)
print("Capacity of number array is \(numbers.capacity)")

//prints Capacity of number array is 7

3. Accessing Elements

3.1 subscript(_:)

Accesses the element at the specified position.

var streetsArray = ["Adams", "Bryant", "Channing", "Douglas", "Evarts"]
streetsArray[1] = "Butler"
print("Subscript 1 is \(streetsArray[1])")

//prints Subscript 1 is Butler

3.2 first

The first element of the collection.

let numberArray = [10, 20, 30, 40, 50]
if let firstNumber = numberArray.first {
    print("FirstNumber is \(firstNumber)")
}

//prints FirstNumber is 10

3.3 last

The last element of the collection.

if let lastNumber = numberArray.last {
    print("Last number in array is \(lastNumber)")
}

//prints Last number in array is 50

3.4 subscript(_:)

Accesses a contiguous subrange of the array’s elements.

let streetArr = ["Adams", "Bryant", "Channing", "Douglas", "Evarts"]
let streetsSlice = streetArr[2 ..< streetArr.endIndex]
print(streetsSlice)

// prints ["Channing", "Douglas", "Evarts"]

let i = streetsSlice.index(of: "Evarts")print(streetArr[i!])

//prints Evarts

4. Adding Elements

4.1 append(_:)

Adds a new element at the end of the array.

var numberArray1 = [1, 2, 3, 4, 5]
numberArray1.append(100)
print(numberArray1)

//prints [1, 2, 3, 4, 5, 100]

4.2 append(contentsOf:)

Adds the elements of a sequence or collection to the end of this collection.

var numbers = [1, 2, 3, 4, 5]
numbers.append(contentsOf: 10...15)
print(numbers)

// Prints "[1, 2, 3, 4, 5, 10, 11, 12, 13, 14, 15]"

4.3 insert(_:at:)

Inserts a new element at the specified position.

numberArray1.insert(100, at: 3)
numberArray1.insert(200, at: numberArray1.endIndex)
print(numberArray1)

//prints [1, 2, 3, 100, 4, 5, 100, 10, 11, 12, 13, 14, 15, 200]

4.4 insert(contentsOf:at:)

Inserts the elements of a sequence into the collection at the specified position.

numberArray1.insert(contentsOf: 100...103, at: 3)
print(numberArray1)
//prints [1, 2, 3, 100, 101, 102, 103, 100, 4, 5, 100, 10, 11, 12, 13, 14, 15, 200]

4.5 replaceSubrange(_:with:)

Replaces a range of elements with the elements in the specified collection.

var nums = [10, 20, 30, 40, 50]
nums.replaceSubrange(1...3, with: repeatElement(1, count: 5))
print(nums)

//prints [10, 1, 1, 1, 1, 1, 50]

4.6 reserveCapacity(_:)

Reserves enough space to store the specified number of elements.

var values: [Int] = [0, 1, 2, 3]

   func addTenQuadratic() {
      let newCount = values.count + 10
      values.reserveCapacity(newCount)
      for n in values.count..<newCount {
          values.append(n)
      }
  }
print(values)

//prints [0, 1, 2, 3]

5. Removing Elements

5.1 remove(at:)

Removes and returns the element at the specified position.

var measurements: [Double] = [1.1, 1.5, 2.9, 1.2, 1.5, 1.3, 1.2]
let removed = measurements.remove(at: 2)
print(measurements)

//prints [1.1000000000000001, 1.5, 1.2, 1.5, 1.3, 1.2]

5.2 removeFirst(_:)

Removes the specified number of elements from the beginning of the collection.

var bugs = ["Aphid", "Bumblebee", "Cicada", "Damselfly", "Earwig"]
bugs.removeFirst(3)
print(bugs)

//prints ["Damselfly", "Earwig"]

5.3 removeLast(_:)

Removes the specified number of elements from the end of the collection.

bugs.removeLast(1)
print(bugs)

//prints ["Damselfly"]

5.4 removeSubrange(_:)

Removes the elements in the specified subrange from the collection.

var measurements1 = [1.2, 1.5, 2.9, 1.2, 1.5]
measurements1.removeSubrange(1..<4)
print(measurements1)

//prints [1.2, 1.5]

5.5 removeAll())

Removes all elements from the collection.

measurements1.removeAll()
print(measurements1)

//prints []

6. Finding Elements

6.1 contains(where:)

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

enum HTTPResponse {
    case ok
    case error(Int)
}

let lastThreeResponses: [HTTPResponse] = [.ok, .ok, .error(404)]
let hadError = lastThreeResponses.contains { element in
    if case .error = element {
        return true
    } else {
        return false
    }
}
print(hadError)

//prints true

6.2 first(where:)

Returns the first element of the sequence that satisfies the given predicate.

let numbers1 = [3, 7, 4, -2, 9, -6, 10, 1]
if let firstNegative = numbers1.first(where: { $0 < 0 }) {
    print("The first negative number is \(firstNegative).")
}

//prints The first negative number is -2.

6.3 index(of:)

Returns the first index where the specified value appears in the collection.

var students = ["Ben", "Ivy", "Jordell", "Maxime"]
if let i = students.index(of: "Maxime") {
    students[i] = "Max"
}
print(students)

//prints ["Ben", "Ivy", "Jordell", "Max"]

6.4 min()

Returns the minimum element in the sequence.

let heights = [67.5, 65.7, 64.3, 61.1, 58.5, 60.3, 64.9]
let lowestHeight = heights.min()
print(lowestHeight ?? "none")

//prints 58.5

6.5 min(by:)

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

let hues = ["Heliotrope": 296, "Coral": 16, "Aquamarine": 156]
let leastHue = hues.min { a, b in a.value < b.value }
print(leastHue!)

//prints (key: "Coral", value: 16)

6.6 max()

Returns the maximum element in the sequence.

let greatestHeight = heights.max()
print(greatestHeight!)

//67.5

6.7 max(by:)

Returns the maximum element in the sequence, using the given predicate as the comparison between elements.

let greatestHue1 = hues.max { a, b in a.value < b.value }
print(greatestHue1!)

//prints (key: "Heliotrope", value: 296)

7. Selecting Elements

7.1 prefix(_:)

Returns a subsequence, up to the specified maximum length, containing the initial elements of the collection.

let numbersA = [1, 2, 3, 4, 5]
print(numbersA.prefix(2))

//prints [1, 2]

7.2 prefix(through:)

Returns a subsequence from the start of the collection through the specified position.

let numbersAr = [10, 20, 30, 40, 50, 60]
if let i = numbersAr.index(of: 40) {
    print(numbersAr.prefix(through: i))
}

//prints [10, 20, 30, 40]

7.3 suffix(_:)

Returns a subsequence, up to the given maximum length, containing the final elements of the collection.

let numbersA = [1, 2, 3, 4, 5]
print(numbersA.suffix(2))

//prints [4, 5]

7.4 suffix(from:)

Returns a subsequence from the specified position to the end of the collection.

let numbersS = [10, 20, 30, 40, 50, 60]
if let i = numbersS.index(of: 40) {
    print(numbersS.suffix(from: i))
}

//prints [40, 50, 60]

8. Iterating Over an Array's Elements

8.1 forEach(_:)

Calls the given closure on each element in the sequence in the same order as a for-in loop.

let numberWords = ["one", "two", "three"]
for word in numberWords {
    print(word)
}

//prints one
two
three

8.2 enumerated()

Returns a sequence of pairs (n, x), where n represents a consecutive integer starting at zero, and x represents an element of the sequence.

for (n, c) in "Swift".enumerated() {
    print("\(n): '\(c)'")
}

//prints
0: 'S'
1: 'w'
2: 'i'
3: 'f'
4: 't'

9. Sorting an Array

9.1 sort()

Sorts the collection in place.

var students1 = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
students1.sort()
print(students1)

//prints ["Abena", "Akosua", "Kofi", "Kweku", "Peter"]

9.2 sort(by:)

Sorts the collection in place, using the given predicate as the comparison between elements.

enum HTTPResponse1 {
    case ok
    case error(Int)
}

var responses: [HTTPResponse1] = [.error(500), .ok, .ok, .error(404), .error(403)]
responses.sort {
    switch ($0, $1) {
    // Order errors by code
    case let (.error(aCode), .error(bCode)):
        return aCode < bCode

    // All successes are equivalent, so none is before any other
    case (.ok, .ok): return false

    // Order errors before successes
    case (.error, .ok): return true
    case (.ok, .error): return false
    }
}
print(responses)

//prints [TempCode.HTTPResponse1.error(403), TempCode.HTTPResponse1.error(404), TempCode.HTTPResponse1.error(500), TempCode.HTTPResponse1.ok, TempCode.HTTPResponse1.ok]

9.3 sorted()

Returns the elements of the collection, sorted.

let studentsT: Set = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
let sortedStudents = studentsT.sorted()
print(sortedStudents)

//prints ["Abena", "Akosua", "Kofi", "Kweku", "Peter"]

9.4 reversed()

Returns a view presenting the elements of the collection in reverse order.

let numbersC = [3, 5, 7]
for number in numbersC.reversed() {
    print(number)

//prints 7
5
3

10. Excluding Elements

10.1 dropFirst()

Returns a subsequence containing all but the first element of the sequence.

let numbersW = [1, 2, 3, 4, 5]
print(numbersW.dropFirst())

//prints [2, 3, 4, 5]

10.2 dropLast()

Returns a subsequence containing all but the last element of the sequence.

let numbersW = [1, 2, 3, 4, 5]
print(numbersW.dropLast())

//prints [1, 2, 3, 4]

11. Manipulating Indices

11.1 startIndex

The position of the first element in a nonempty array.

print(numbersW.startIndex)

//prints 0

11.2 endIndex

The array’s “past the end” position—that is, the position one greater than the last valid subscript argument.

print(numbersW.endIndex)

//prints 5

12. Splitting and Joining Elements

12.1 split(separator:maxSplits:omittingEmptySubsequences:)

Returns the longest possible subsequences of the sequence, in order, around elements equal to the given element.

let line = "BLANCHE:   I don't want realism. I want magic!"
print(line.split(separator: " ") .map(String.init))

//prints ["BLANCHE:", "I", "don\'t", "want", "realism.", "I", "want", "magic!"]

12.2 split(maxSplits:omittingEmptySubsequences:whereSeparator:)

Returns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.

print(line.split(whereSeparator: { $0 == "a" }))

//prints ["BLANCHE:   I don\'t w", "nt re", "lism. I w", "nt m", "gic!"]

12.3 joined(separator:)

Returns a new string by concatenating the elements of the sequence, adding the given separator between each element.

let cast = ["Vivien", "Marlon", "Kim", "Karl"]
let list = cast.joined(separator: ", ")
print(list)

//prints Vivien, Marlon, Kim, Karl

12.4 joined()

Returns the elements of this collection of collections, concatenated.

let ranges = [0..<3, 8..<10, 15..<17]
for range in ranges {
  print(range)
}
// Prints "0..<3"
// Prints "8..<10"
// Prints "15..<17"

for index in ranges.joined() {
    print(index, terminator: " ")
}

// Prints: "0 1 2 8 9 15 16"

13. Comparing Arrays

13.1 ==(_: _:)

Returns true if these arrays contain the same elements.

let arr1 = [1, 2, 2, 3, 4, 5]
let arr2 = [1, 3, 6, 7, 9 ,10]
if (arr1 == arr2){
	print("EQUAL ARRAY\(arr1)")
}else{
	print("NOT EQUAL")
}

//prints NOT EQUAL

13.2 !=(::)

Returns true if the arrays do not contain the same elements.

let arr1 = [1, 2, 2, 3, 4, 5]
let arr2 = [1, 3, 6, 7, 9 ,10]
if (arr1 != arr2){
	print("Not EQUAL")
}else{
	print("EQUAL")
}

//prints Not EQUAL

13.3 elementsEqual(_:)

Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.

if (arr1.elementsEqual(arr2)){
	print("equal elements")
}else{
	print("Not equal")
}

//prints Not equal

13.4 starts(with:)

Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.

let a = 1...3
let b = 1...10
print(b.starts(with: a))

//prints true

13.5 lexicographicallyPrecedes(_:)

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (<) to compare elements.

let a = [1, 2, 2, 2]
let b = [1, 2, 3, 4]
print(a.lexicographicallyPrecedes(b))

// Prints "true"

print(b.lexicographicallyPrecedes(b))

// Prints "false"

14. Describing an Array

14.1 description

A textual representation of the array and its elements.

let ax = [1, 2, 2, 2]
print(ax.description)

//prints [1, 2, 2, 2]

14.2 debugDescription

A textual representation of the array and its elements, suitable for debugging.

let ax = [1, 2, 2, 2]
print(ax.debugDescription)

//prints [1, 2, 2, 2]

14.3 customMirror

A mirror that reflects the array.

let ax = [1, 2, 2, 2]
print(ax.customMirror)

//prints Mirror for Array<Int>

15. Bridging Between Array and NSArray

When you need to access APIs that require data in an NSArray instance instead of Array, use the type-cast operator (as) to bridge your instance.
For bridging to be possible, the Element type of your array must be a class, an @objc protocol (a protocol imported from Objective-C or marked with the @objc attribute), or a type that bridges to a Foundation type.

import Foundation
var arr : NSMutableArray = ["Pencil", "Eraser", "Notebook"]

func bar (a : NSMutableArray)
{
    a[2] = "Pen"
}

bar(a : arr)

print (Array(arr))

//prints ["Pencil", "Eraser", "Pen"]

Next - Set by Example

You can download the swift playground of all above examples from Here

Swift iOS Swift4

Array by Example - Swift Programming Language

Overview

1. Creating and Initializing an Array

1.1 Creating an Array

1.2 init(repeating:count:)

1.3 init(_:)

1.4 init()

2. Inspecting an Array

2.1 isEmpty

2.2 count

2.3 capacity

3. Accessing Elements

3.1 subscript(_:)

3.2 first

3.3 last

3.4 subscript(_:)

4. Adding Elements

4.1 append(_:)

4.2 append(contentsOf:)

4.3 insert(_:at:)

4.4 insert(contentsOf:at:)

4.5 replaceSubrange(_:with:)

4.6 reserveCapacity(_:)

5. Removing Elements

5.1 remove(at:)

5.2 removeFirst(_:)

5.3 removeLast(_:)

5.4 removeSubrange(_:)

5.5 removeAll())

6. Finding Elements

6.1 contains(where:)

6.2 first(where:)

6.3 index(of:)

6.4 min()

6.5 min(by:)

6.6 max()

6.7 max(by:)

7. Selecting Elements

7.1 prefix(_:)

7.2 prefix(through:)

7.3 suffix(_:)

7.4 suffix(from:)

8. Iterating Over an Array's Elements

8.1 forEach(_:)

8.2 enumerated()

9. Sorting an Array

9.1 sort()

9.2 sort(by:)

9.3 sorted()

9.4 reversed()

10. Excluding Elements

10.1 dropFirst()

10.2 dropLast()

11. Manipulating Indices

11.1 startIndex

11.2 endIndex

12. Splitting and Joining Elements

12.1 split(separator:maxSplits:omittingEmptySubsequences:)

12.2 split(maxSplits:omittingEmptySubsequences:whereSeparator:)

12.3 joined(separator:)

12.4 joined()

13. Comparing Arrays

13.1 ==(_: _:)

13.2 !=(::)

13.3 elementsEqual(_:)

13.4 starts(with:)

13.5 lexicographicallyPrecedes(_:)

14. Describing an Array

14.1 description

14.2 debugDescription

14.3 customMirror

15. Bridging Between Array and NSArray

You can download the swift playground of all above examples from Here

Turbo C++ Error - Unable to Open Include File 'STDIO.H'

Set by Example - Swift Programming Language

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