Simple syntax for Swift's entry (III.)

Collection array

• The array uses the [] definition, which is the same as OC

//: [Int]let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

• Traverse

for num in numbers {    print(num)}

• Get the specified item content by subscript

let num1 = numbers[0]let num2 = numbers[1]

• Variable & non-volatile
  • letDefining immutable Groups
  • varDefining a mutable array

let array = ["zhangsan", "lisi"]//: 不能向不可变数组中追加内容//array.append("wangwu")var array1 = ["zhangsan", "lisi"]//: 向可变数组中追加内容array1.append("wangwu")

• Types of arrays
  • If all content types are consistent during initialization, the content of that type is saved in the optional array
  • If all content types are inconsistent during initialization, the selected array holds theNSObject

//: array1 仅允许追加 String 类型的值//array1.append(18)var array2 = ["zhangsan", 18]//: 在 Swift 中，数字可以直接添加到集合，不需要再转换成 `NSNumber`array2.append(100)//: 在 Swift 中，如果将结构体对象添加到集合，仍然需要转换成 `NSValue`array2.append(NSValue(CGPoint: CGPoint(x: 10, y: 10)))

• Definition and instantiation of arrays
  • Use : to define only the type of an array
  • Add value is not allowed before instantiation
  • Use [类型]() the ability to instantiate an empty array

var array3: [String]//: 实例化之前不允许添加值//array3.append("laowang")//: 实例化一个空的数组array3 = [String]()array3.append("laowang")

• Merging of arrays
  • Must be an array of the same type to be able to merge
  • In development, the types of objects that are normally stored in arrays are the same!

array3 += array1//: 必须是相同类型的数组才能够合并，以下两句代码都是不允许的//array3 += array2//array2 += array3

• Deletion of arrays

//: 删除指定位置的元素array3.removeAtIndex(3)//: 清空数组array3.removeAll()

• Memory allocation
  • If you append an element to an array that exceeds the capacity, it is directly based on the existing capacity * 2

var list = [Int]()for i in 0...16 { list.append(i) print("添加 \(i) 容量 \(list.capacity)")}

Dictionary

• Defined
  • Use the same [] definition dictionary
  • letImmutable dictionaries
  • varVariable dictionaries
  • [String : NSObject]Is the most commonly used dictionary type

//: [String : NSObject] 是最常用的字典类型var dict = ["name": "zhangsan", "age": 18]

• Assign value
  • Assigning direct use of dict[key] = value formatting
  • If key does not exist, the new value is set
  • If key exists, the existing value is overwritten

//: * 如果 key 不存在，会设置新值dict["title"] = "boss"//: * 如果 key 存在，会覆盖现有值dict["name"] = "lisi"dict

• Traverse
  • k, v can write casually
  • The front iskey
  • The Back isvalue

//: 遍历for (k, v) in dict {    print("\(k) ~~~ \(v)")}

• Merging dictionaries
  • If key does not exist, a new value will be established, otherwise the existing value will be overwritten

//: 合并字典var dict1 = [String: NSObject]()dict1["nickname"] = "大老虎"dict1["age"] = 100//: 如果 key 不存在，会建立新值，否则会覆盖现有值for (k, v) in dict1 { dict[k] = v}print(dict)

Simple syntax for Swift's entry (III.)