swift基礎(chǔ)語法(一)
swift基礎(chǔ)語法二主要講數(shù)據(jù)類型

1.字符串

1.在swift中String是一個結(jié)構(gòu)體,性能更高

String的定義.png

2.字符串的定義

var str1 = "zifuchuan" //字符串變量
let str1 = "字符串" //字符串常量

3.字符的定義

var char1 : Character = "z"http://字符變量
let char1 :  Character = "z" //字符常量

2.String直接支持遍歷

var str2 = "hello world"
for s in str.characters{    
    print(s)
}

3.支持String和NSString的無縫轉(zhuǎn)換

let strin = "string"
//String轉(zhuǎn)換為NSString
var st = strin as NSString
//NSString轉(zhuǎn)String
var str12 = st as String

let strin = "string"
let st4 = "\(st3)\(strin)"
let st5 = st3 + strin

4.字符串的拼接

格式:\(變量或常量的名字)
let age12 = 18
let height = 1.88
let  st3 = "age is \(age),heigth is \(height)"

5.字符串格式化

//2:3 -> 02:03
let min = 2
let second = 3
let time = String(format: "%02d:%02d",arguments:[min,second])

6.字符串截取

//3.字符串截取
let urlString = "www.baidu.com"
//提示:不要使用string方法,因為index創(chuàng)建不好創(chuàng)建
//urlString.substringToIndex(<#T##index: Index##Index#>)
//String轉(zhuǎn)nsstring,只需要在string后面加上as nsstring
let prefixStrinf = (urlString as NSString).substringToIndex(3)
//中間
let middel = (urlString as  NSString).substringWithRange(NSRange(location: 4, length: 3))
//末尾
let subFixString = (urlString as NSString).substringFromIndex(8)

7.字符串進行補充

//字符串
var str: String = "hello"
let str2 = String("hello")

str.isEmpty //判斷字符串是否為空

let mark = "!!!"

str + mark //str 和mark都沒發(fā)生改變
str += mark

let name = "liu"
let age3 = 16
let s = "my name is \(name), age is \(age3)"

let s2 = "\\\""http://輸出\\
let s4 = "\""http://輸出"
//字符串的遍歷
for c in str.characters{
print(c)
}

//mark2是一個字符
let mark2 : Character = "!"
str + String(mark2)
str.append(mark2) //直接改變str這個變量

//
let englishLetter : Character = "A"
let chineseLetter : Character = "王"
let  coolGuy : Character = "\u{1F60E}"

var coolLetters = "abc"
coolLetters.characters.count

var chineseLetters = "實際上"
chineseLetters.characters.count

var coolGuyss = "\u{1F60E}\u{1F60E}\u{1F60E}"
coolGuyss.characters.count

//swift中的字符串是基于unicode符的,更傾向于人類對字符的理解
//使得swift中對字符串的處理速度不夠快

//str[0]//是不可以的

//獲取字符串的字符
//String.Index

let startIndex = str.startIndex
startIndex
str[startIndex]//第一個字符
str[startIndex.advancedBy(5)]//第五個字符

let spaceIndex = startIndex.advancedBy(5)
spaceIndex
str[spaceIndex]

str[spaceIndex.predecessor()]//前一個字符
str[spaceIndex.successor()]//后一個字符

let endIndex = str.endIndex //endIndex不是字符串最后一個字符的索引,而在字符串最后一個字符之后的位置,
//[startIndex,endIndex)構(gòu)成一個前閉后開的區(qū)間,整個字符串字符在startIndex  .....endIndex-1的位置

str[endIndex.predecessor()]//最后一個字符

str[startIndex..<spaceIndex]
let rang = startIndex..<spaceIndex.predecessor()
str.replaceRange(rang, with: "hi")

str.appendContentsOf("!!!")
str.insert("?", atIndex: str.endIndex)
str.removeAtIndex(str.endIndex.predecessor())//刪除最后一個字符
str
str.removeRange(str.endIndex.advancedBy(-2)..<str.endIndex)//刪除最后兩個字符
str.uppercaseString
str.lowercaseString
str.capitalizedString //詞在首字母大學(xué)
str.containsString("hello")
str.hasPrefix("He")
str.hasSuffix("ft")

let s1 = "one third is \(1.0 / 3.0)"
//NSString  as 橋接
let sa : String = NSString(format: "one third is %.2f",1.0/3.0) as String

var sn : NSString = "ONET"
sn.substringToIndex(4)
sn.substringFromIndex(4)
sn.substringWithRange(NSRange.init(location: 2, length: 2))

//NSString 不是基于unicode
sn.length

let s6 = "----   hello -----" as NSString
//去除字符串中的冗余
s6.stringByTrimmingCharactersInSet(NSCharacterSet(charactersInString: "-"))
s6

2.數(shù)組

使用let定義的數(shù)組是不可變數(shù)組
使用var定義的數(shù)組是可變數(shù)組
數(shù)組的初始化:數(shù)組的類型Array
方式一.泛型:<數(shù)組類型>

let array : Array<String> = ["1","2"]

方式二:

let name: [String] = ["why","y2"]

方式三:

let name3 = ["why","ys","lmj"]

可變數(shù)組

var name4 : [String] = ["why"]

添加元素

name4.append("y1")

定義一個空的數(shù)組

var name5 : [String] = Array()
var name6: [String] = [String]()

數(shù)組的基本操作:
數(shù)組中放任意類型可以使用NSObject或者AnyObject

var name7 : [AnyObject] = [AnyObject]()
name7.append("why")
name7.append(12)
name7.append(1.88)

移除:

移除之后一個元素
name7.removeLast()
移除特定下標(biāo)的元素
name7.removeAtIndex(2)    
移除全部元素
name7.removeAll()

修改元素

name7[0] = "ssss"

取出數(shù)組對應(yīng)的元素

方法一:通過下標(biāo)值來遍歷
for i in 0..<name7.count{
    print(name7[i])
}

方式二: for in遍歷
for item in array{
    print(item)
}

方式三:區(qū)間遍歷
for item in name[0..<2]{
print(item)
} 

數(shù)組的合并
let array1 = ["why" ,"+86",18]
let array2 = [1.88,"china"]
let array3 = array1 + array2
var  array5 = [AnyObject]()
let array4 = [1.88, 19]
for item in array4{
    array5.append(item)
}
for item in array3
{
    array5.append(item)
}
array5

3.字典

字典的初始化

1.方式一
let dict : Dictionary<String,AnyObject> = ["name" : "why","age" : 18]
2.方式二
let dict2 : [String : AnyObject] = ["name" : "why","age" : 18]
方式三
let dict3 = ["name" : "why","age" : 18]

可變字典

1.方式1
var dict4 = Dictionary<String,AnyObject>()
2.方式二
var dict5 = [String : AnyObject]()
3.方式三
var dict6 = ["name" : "why","age" : 18]

字典操作

var dict7 = [String:AnyObject]()

添加元素

dict7["name"] = "why"
dict7["age"] = 17
dict7["height"] = 1.88

刪除元素.刪除元素,并返回刪除的元素

dict7.removeValueForKey("age")

修改元素

注意:通過該方式修改的元素,如果有對應(yīng)的鍵則修改,沒有則添加
dict7["name"] = "123"
//取出
dict7["name"]

遍歷字典

//1.遍歷字典中的所有鍵
for key in dict7.keys{
    print(key)
}
//2.遍歷字典的所有值
for value in dict7.values{
    print(value)
}
//3.遍歷所有的鍵值對
for (key,value) in dict{
print(key)
print(value)
}

字典的合并

let dic1 = ["name" : "why","age" : 18]
var dic2 = ["phone": "110","height" : 1.88]
//注意:無論字典的類型是否一致,都不可以直接相加
for (key1,value1) in dic1{
    dic2[key1] = value1
}

4.元祖

//定義元祖方式1
let a1 = ("why",18,1.88)
//方式2
let b = (name : "why",age: 18,height : 1.88)
//方式三
let (name1,age123,height1) = ("why",18,1.88)
//元祖的使用
let error = (404,"Not Found")
error.0
error.1

let error1 = (errorCode : 404,errorInfo: "not found")
error1.errorCode
error1.errorInfo

let (errorCode1 ,errorInfo1) = (404,"not fonund")
errorCode1
errorInfo1

5.可選型

1.在oc開發(fā)中,如果有一個變量暫停不使用,可以賦值0(基本數(shù)據(jù)類型)或者賦值為空(對象類型)
2.在swift中,nil也是一個特殊的類型,因為和真實類型不匹配不能賦值的(因為swift是強語言)
但是開發(fā)中賦值為nil,是在所難免的,所有推出了可選類型

可選類型取值
1.空值
2.有值

//定義可選類型,方式1 Optional<String>
var name20 : Optional<String>
name20 = "why"

//錯誤寫法 類型不匹配
//let info = "my name is" + name20

print(name20) //optional("why")

//取出可選類型的值
//取值:可選類型 + !強制解包
print(name20!)

let info = "my name is" + name20!

let phoneNum :Optional<Int>
//2>方式二(語法糖)
var phoneNUm2 : String? = nil
phoneNUm2 = "+ 89 110"
//let phoneInfo = "my phoneNume" + phoneNUm2!

使用注意:如果一個可選類型里面沒有值,強制解包會報錯,所有在強制解包前要對類型進行判斷,

//如果有值才進行解包
 if  phoneNUm2 != nil{  
let phoneInfo = "my phoneNume" + phoneNUm2!    
}

2.可選綁定:判斷phoneNUm2是否有值
1>如果沒有值,直接跳過
2>如果有值,將可選類型進行解包,并且將解包的后的值賦值給temponeNum

if let temponeNum = phoneNUm2{
print(temponeNum)
}

可選類似的使用,更加安全