Swift学习:字符串和集合类型

字符串 String

1.是一个Unicode 编码,16位字符的字符序列
2.与 NSString 支持无缝互操作
3.被定义为 struct 拷贝时具有值语义
4.虽然是一个struct 但内部包含一个指向堆上的内容指针(特殊),指向对象存放真正内容

5.变量字符串 var str;常量字符串let str
6.获取字符串中的字符:

var str1 = "Hello"


//枚举字符
for item in str1.characters{
    print(item)
}

for index in str1.characters.indices{
    print(str1[index])
}

7.使用 append 和+连接字符串

//--连接字符串--
str1.appendContentsOf(str2)//m1
var str3 = str1 + str2//m2

var char:Character = "!"
str1.append(char)

8.字符转义

//--字符串转义--
let heart = "\u{2665}"
let words = "\tHello"

9.字符串插值

//--字符串插值--
var x=100,y=200.0
var text = "[\(x),\(y)]"

10.字符串比较

//--字符串比较--
var text1 = "Swift",text2 = "swift"
print(text1 == text2)//大小写敏感

//忽略大小写
if(text1.rangeOfString(text2,
    options: NSStringCompareOptions.CaseInsensitiveSearch) == nil){
        print("no find")
    }
else{
    print("find")
}

copy on write

1.同一字符串拷贝到不同变量,不同变量共享同一份内存,支持字符串随时改变
2.尽量不要改变字符串,用静态的 let

集合类型

1.array
一个有序的元素序列,支持随机存取,动态长度

2.set

  • 无序集合,其存储的值不能重复
  • 集合元素必须有哈希值(支持 Hashable 协议)

3.dictionary

  • 无序集合,存储 key-value, 其中 key 唯一, value 课重复
  • key 必须有哈希值

注意:都为,struct 类型,值类型,但是同 string 一样,内部包含一个指向堆上的元素指针

array

import Foundation



//--数组的声明与实例化--
var array1 = [1,2,3,4,5]
var array2:[Int]
var array3:Array<Int>

array2 = [Int](count:5,repeatedValue:10)
array3 = [Int]()


//--内存模型--
print(sizeofValue(array1))
print(strideofValue(array1))
print(sizeofValue(array2))
print(strideofValue(array2))
print(sizeofValue(array3))
print(strideofValue(array3))

array3.append(1)
array3.append(2)
array3.append(3)
print(sizeofValue(array3))
print(strideofValue(array3))


class MyClass{
    init(){
        print("MyClass.init")
    }
    deinit{
        print("MyClass.deinit")
    }
}


func process(){
    var objectArray=[MyClass]()
    
    for _ in 1...5{
        objectArray.append(MyClass())
    }
    
    print(objectArray.count)
    
    objectArray.removeAll()
    
    
}

process()


//--变量数组和常量数组--
var array5 = [1,2,3]
let array6 = [1,2,3]
array5.append(40)
array5[2]=4
print(array5)





//--数组操作--
for item in array5{
    print(item)
}

print("排序:")
for item in array5.sort( > ){
    print("\(item)")
}


for(index, value) in array5.enumerate(){
    print("\(index): \(value)")
}

for index in 0..<array5.count {
    print(array5[index])
}

var array7=array5+array6
array5+=[5,6,7]
print(array5.count)
array5[4...6]=[6,7,8]
print(array5)
array5.insert(5, atIndex:4) //代价较大
print(array5)
array5.removeAtIndex(7) //代价较大
print(array5)

//--缓存容量--
var array8=[1,2,3]
print("\(array8.count), \(array8.capacity)")
array8.reserveCapacity(120)//分配大小
for index in 4...100{
    array8.append(index)
    print("\(array8.count), \(array8.capacity)")
}


//--copy-on-write--
var array4=array1
array1[0]=10
array1.append(20)
print(array1)
print(array4)

//--排序--
var arr = [4,3,5,2,6,1]
arr.sortInPlace()
arr.sortInPlace {$0 > $1} // *** [1, 2, 3, 4, 5, 6]
arr = [4,3,5,2,6,1]
arr.sortInPlace(>) // *** [1, 2, 3, 4, 5, 6]

print(arr)




set

var words = Set<String>()

words.insert("Hello")
words.insert("Swift")
words.insert("Language")
words.insert("Swift")

print(sizeofValue(words))
words.count
words=[]
words.count
print(sizeofValue(words))


var cities1:Set<String>
cities1=["Shanghai","Beijing","New York","Shanghai"]
cities1.count

for city in cities1{
    print(city)
}

for city in cities1.sort(){//排序
    print(city)
}

for city in cities1.sort( > ){//反序
    print(city)
}


cities1.count
cities1.contains("New York")

var cities2:Set=["New York", "Shanghai"]

print(cities1.isSupersetOf(cities2))

print(cities1==cities2)
cities1.remove("Beijing")
print(cities1==cities2)
print(cities1.isSupersetOf(cities2))

dictionary


import Foundation

var dictionary1 = [String:Int]()
var dictionary2 : Dictionary<String,Int>
dictionary2=["Jason":36, "Tom":31, "Marty":44]

print(sizeofValue(dictionary1))
print(sizeofValue(dictionary2))

for(name, age) in dictionary2{
    print("The Age of \(name) is: \(age)")
}

for name in dictionary2.keys{
    print(name)
}

for name in dictionary2.keys.sort(){
    print(name)
}

for value in dictionary2.values{
    print(value)
}
for value in dictionary2.values.sort({$0 > $1}){
    print(value)
}


dictionary2.count
dictionary2["Tom"]=32
dictionary2.updateValue(33,forKey:"Tom")
dictionary2["Julie"]=28
dictionary2.count

dictionary2["Marty"]=nil
dictionary2.removeValueForKey("Tom")
dictionary2.count


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