Swift Learning note seven: Collection

Arrays Array

• Creation of arrays

• • Use @[] to define an array in OC, using [] to define an array in Swift
  • [Type] means that all elements of that type are stored in the array.
  • Elements in the array in Swift can be basic data types

//Create an arrayvar array1:array<int>Vararray2:array<Int> = [2,3]var array3: [Int]var array33=[Int] () array1= Array (arrayliteral:1,2,3,4) var array4= Array (Repeatelement ("A", Count:Ten)) Vararray44= Array (repeating:0.0, Count:3) //create an empty arrayvar array5:array<int> =[]var array6: [Int]=Array ()//if the types in the data are inconsistent, specify the type array<any>Let array7:array<any> = ["1",1, p]

• Traversal of an array

//1. Follow the subscript traversal forIinch 0.. <array.count{Print (Array[i])}//2. for in traversal forIincharray{Print (i)}//3. Enum block traversal, while traversing subscript and element forIincharray.enumerated () {print (i)}//4. Traversing subscripts and elements for(Index, Element)incharray.enumerated () {print ("\ (index)---\ (element)")}  //5. Reverse-order Traversal forIincharray.reversed () {print (i)} forSincharray.enumerated (). Reversed () {print (s)}

• Merging additions and deletions of arrays

//OC Medium-Number component variable Nsmutablearray ()/Immutable Nsarray ()//array variable var/immutable let in Swiftvar arr = ["1","2","3"] //Append ElementArr.append ("0") //Modify, Position by subscriptarr[0] ="AAA"  //array out of bounds---Index outof Range//array[5] = "XXX"//DeleteArr.remove (at:3) //Delete all, and reserve spaceArr.removeall (keepingcapacity:true)  //Array Mergingvar arr1 = ["3"," One","2"]var arr2= ["AAA","CCC","BB","FFF"] //Note: The two types of arrays to be merged must be consistentarr1 + = arr2

• Sorting of arrays

// Array Sorting 1 2 3 4  //  array Sort By default is ascending order  //  descending arrangement array1.sort (by: >   //  ascending arrangement Array1.sort (by: <)

Dictionary Dictionary

• OC definition Dictionary @{}, Swift definition dictionary [key:value]

// the declaration of the Dictionary and the creation of var dic1:dictionary<int, string>= Dictionary (dictionaryliteral: (1,"  1"), (2,"2"= [1:"  1 ", 2:"2"]var dic5 = [int:string] ()

• Dictionary additions and Deletions change

var dict: [String:any] = ["name":"Zhang"," Age": -] //new and modified in the dictionary is the value of the key: If the key exists, it is modified, if the key does not exist, it means that the new//Newdict["title"] ="AAA"  //Modifydict["name"] ="Li"Dict.updatevalue ("00000000", Forkey:"name") Dict.updatevalue ("PPP", Forkey:"XXX")  //Delete: If there is a corresponding key, then delete, if not the corresponding key, do not operateDict.removevalue (Forkey:" Age") print (dict) dict.removevalue (forkey:" Age") print (dict)

• The traversal of a dictionary

Let Dict1: [String:any] = ["name":"Zhang"," Age": -,"title":"name"]  forEinchdict1{print (e)} for(Key, value)inchdict1{Print ("\ (key)---\ (value)")}  //Mergingvar dict3: [String:any] = ["name":"Zhang"," Age": -,"title":"name"]let DICT4: [String:any]= ["name":"Li","Height":1.8] //Traverse, and then click Set for(Key, value)inchdict4{Dict3[key]=Value}

Set set

• Creation of Set

// Create collection var set1:set<int> = [1234]var set2:set<string > = Set (arrayliteral:"1","2","3  "= Set (arrayliteral:1,2,3)  var set4:set <Int> = []

• Common operations for collections

//get the number of elementsSet1.count//determines whether the collection is an empty collectionifset1.isempty{Print ("collection is empty")} //determines whether an element is contained in the collectionifSet1.contains (2) {print ("contains this element in the collection")} //InsertSet1.insert (5) //gets the subscript at the specified positionvar setindex = Set1.index (of:4)//removes the element that specifies the subscriptSet1.remove (at:setindex!) //removing the specified elementSet1.remove (1)

• Mathematical operations of sets

var setn:set<int> = [1,2,3,4,5,6]varsetm:set<Int> = [4,5,6,7,8] //perform a intersection operation: Take the intersection of two setsvar setinter =setn.intersection (Setm)//make symmertricdifference take two different parts of the collectionvar setdif =setn.symmetricdifference (Setm)//Union of the collection, and setvar Setuni =setn.union (Setm)//subtracting operations for collections: Use a set to intercept another collectionvar setsub =setn.subtracting (Setm) Setn==Setm var setsub1:set<Int> = [1,2,3] //determines whether a subset or parent setSetsub1.issubset (OF:SETN) setn.issuperset (OF:SETSUB1)//determine if a true subset or true parent setSetsub1.isstrictsubset (OF:SETN) setn.isstrictsuperset (OF:SETSUB1)

• Traversal of a collection

 var setsub1:set<int> = [1 , 2 , Span style= "COLOR: #800080" >3  ]  for  Item in   setsub1{print (item)}  for  item in   Setsub1.enumerated () {print (item)}  for  (Index, item) in   setsub1.enumerated () {print ( "  \ (index): \ (item)   "  for  index in  Span style= "COLOR: #000000" > setsub1.indices{print (Setsub1[index])}  

Swift Learning note seven: Collection