Swift Short Notes : Swift Chapter 5 Collections

Collection Types are structs not classes.

Same like objC Array (Ordered collection of values), Set (unordered collection of unique values) and Dictionary(Key- value mapping).

Swift collection type implemented as generic collection(template) and they are bridged to objC foundation’s NSArray. (Bridging is done with as keyword).

Array: 

Some Ex:

var someInts = [Int]()

let arraInt :Array<Int>

var threeDoubles = [Double](count: 3, repeatedValue: 0.0)

shoppingList[4...6] = ["Bananas", "Apples"]

for item in shoppingList {

print(item)

}

for (index, value) in shoppingList.enumerate() {

print("Item \(index + 1): \(value)")

}

Set: Storing type must be hashable .(Hashable needs to conform to Hashable protocol. Hashable consforms to equatable so == needs to be implemented.). Set has set property like intersect, subset, union etc

Some Ex

var letters = Set<Character>()

var favoriteGenres: Set = ["Rock", "Classical", "Hip hop"]

for genre in favoriteGenres {

print("\(genre)") 

}

Dictionary :(Key must be hashable)

Some Ex:

var namesOfIntegers = [Int: String]()

var airports: [String: String] = ["YYZ": "Toronto Pearson", "DUB": "Dublin"]

for (airportCode, airportName) in airports {

print("\(airportCode): \(airportName)")

}

for airportCode in airports.keys {

print("Airport code: \(airportCode)")

}

for airportName in airports.values {

print("Airport name: \(airportName)")

}

Items in Dictionary may not be iterated in same order in which they inserted.