Recently, I have read many tutorials and daishen’s blog during my study of Swift. Finally, I put my notes here for easy review

W3cschool -Swift tutorial, YungFan’s brief book (recommended to have a look, some knowledge summary is simply easy to understand)

String & character

1. String

1.1, introduced

The String type in Swift is String, which is a structure with higher performance. Support traversal

1.2. Initialization

Immutable string: let modifier

let str = "hello Objective-C"
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Mutable string: var modifier

var str = "hello Swift"
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Multiline string

"" Thoughts on the quiet night by Li Bai The moonlight was shining before my bed, and I suspected it was frost on the ground. Looking up the bright moon, lower the head to think of home. "" "Copy the code

Meaning Escapes the string

/* If the string contains a backslash "\", there are two ways to solve the problem: Let STR = "string with escape character backslash" //2, let STR = #" string with escape character backslash "#Copy the code

1.3 common operations

Length: count or length

let str = "12345678"
let len1 = str.count  //8

let len2 = (str as NSString).length  //8
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Concatenation: + or append

let str1 = "abc" + "cde"

var str2 = "abc"
str2.append("cde")
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Through:

// let STR = "abcdefg" for STR {print(char)} value) in str.enumerated() { print("\(index) --- \(value)") }Copy the code

Case: lower and uppercased

Let STR = "abcdefg" // all lowercase print(str.lowercased()) // all uppercase print(str.uppercased())Copy the code

Contains or not: contains

let str = "abcdefg"
print(str.contains("cd"))   //true
print(str.contains("c"))    //true
print(str.contains("o"))    //false

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Segmentation: components

Let STR = "abcdefg$$aAAA $$BBBB $$CCC "let desc = str.components(separatedBy: "$$") for item in desc { print(item) }Copy the code

Replacement: replacingOccurrences

let str = "abcdefg$$aaaa$$bbbb$$ccc"
let dest = str.replacingOccurrences(of: "$$", with: "**")
print(dest)
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Intercepting substring:

// write method 1: Print (sub1) // Print (sub1) // Print (sub1) // Print (sub2) // Print (sub1) // Print (sub2) // Print (sub2) // Print (sub1) // Print (sub2) // Print (sub2) // Print (sub2) // Print (sub1) // Print (sub2) // print(sub2) str.suffix(5) print(sub2)Copy the code

Let STR = "Hello World" // take the first 5 strings of a string, Let index1 = str.index(str.startIndex, offsetBy: Let sub1 = STR [str.startIndex..<index1] print(sub1) Let index2 = str.index(str.endIndex, offsetBy: -1) let sub2 = STR [index2..<str.endIndex] print(sub2) let sub2 = STR [index2..<str.endIndex] print(sub2)Copy the code

2, character,

A character is a single character

let char: Character = "A"
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Note:

• Multiple characters will cause an error
• Null characters generate an error

Second, the array

1, the introduction

Swift refers to an Array as an Array. It is a generic set. It is a structure whose elements are ordered and can be repeated

2. Initialize

Immutable arrays: Let modifier

let array : [Any] = ["zhangsan", 18]
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Mutable arrays: var modifier

Var array: [String] = [String]()Copy the code

Initialization format (var can be replaced with let)

Var array1: Array<Any> = ["zhangsan", 18] var array2: Array<Any> = ["zhangsan", 18] Var array3 = ["zhangsan", "lisi"] var array4 = ["zhangsan", "lisi"] Array<Any> array4 = ["zhangsan", "18"]Copy the code

An empty array is initialized

Var emptyArray = [String]()Copy the code

Var emptyArray = [] if the type information can be inferredCopy the code

Initialize an array of type Int with size 3 and default values 0

var array = [Int](repeating: 0, count: 3)
        
print(array) //[0, 0, 0]
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3. Common operations

The length of the

array.count
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The length of the

array.isEmpty
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Increase the data

array.append("zhaoliu")
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Insert data

array.insert("haojian", at: 0)
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Modify the data

array[0] = "wangqi"
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Search data: Value

array[1]
array.first
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Reverse order

array.reverse()
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Merger: +

Array1 = ["zhang", "wang", "li", "zhao"] array2 = [" SAN ", "si", "Wu "] let array3 = array1 + array2 print(array3) // print: ["zhang", "wang", "li", "zhao"," SAN ", "si", "wu"]Copy the code

Capacity: capacity

Var array = [Int]() for I in 0... var array = [Int]() for I in 0... <8 { array.append(i) print("\(array)\(array.capacity)") }Copy the code

4, traverse

Ordinary traversal

for i in 0.. <array.count { print(array[i]) }Copy the code

The for – way in

for item in array {
    print(item)
}
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Interval traversal

// for item in array[0..<2] {print(item)}Copy the code

Tuples traversal

let array = ["zhang", "wang", "li", "zhao", "zhou"] for (index, enumerated() {print("\(index) == \(name)")} /* Print: 0 == Zhang 1 == Wang 2 == Li 3 == zhao 4 == zhou */Copy the code

Third, the dictionary

1, the introduction

The Dictionary type in Swift is Dictionary, which is also a generic collection. It is disordered between elements, health cannot be repeated, and others are similar to OC

2. Initialize

Immutable dictionary: let modifier

// dictdict1: Dictionary<String, Any> = ["age": 18,"name": "zhangsan"] // dict2: [String: Any] = ["age": Dict3 = ["age": 18,"name": "zhangsan"] as [String: Any]Copy the code

Mutable dictionary: var modifier

// dictdict1: Dictionary<String, Any> = ["age": 18,"name": "zhangsan"] dict2: [String: Any] = ["age": Dict3 = ["age": 18,"name": "zhangsan"] as [String: dict3 = ["age": 18,"name": "zhangsan"] // dictdict4 = [dictdict4]() // dictdict5 = [:]Copy the code

3. Common operations

The length of the

dict.count
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Sentenced to empty

dict.isEmpty
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Increase the data

var dict = [String : Int]()
dict["height"] = 18
dict["weight"] = 20
print(dict)
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Delete the data

RemoveValue (forKey: "height") dict["height"] = nilCopy the code

Modify the data

// Dict ["height"] = 55 // dict. UpdateValue (99, forKey: "weight")Copy the code

Query data

// Dict ["name"]Copy the code

merge

Var dict1: [String: a] = ["name" : "zhangsan", "age" : 20] var dict2: [String: b] Any] = ["height" : 180, "phone" : For (key) in dict2 {dict1[key] = value} print(dict1) // print: ["height": 180, "name": "zhangsan", "phone": "18888888888", "age": 20]Copy the code

4, traverse

Walk through all the values in the dictionary

for value in dict.values {
    print(value)
}
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Walk through all the keys in the dictionary

for key in dict.keys {
    print(key)
}
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Walk through all the key-value pairs

/ / are commonly used for (key, value) in dict {print (" \ (key) = = \ (value) ")}Copy the code

Traversal in enumeration mode

var dict: [String : Any] = ["name" : "zhangsan", "age" : 20, "height" : 180, "phone" : "18888888888"] // Value) for (index, value) in dict.enumerated() {print("\(index) == \(value)")} /* Print: 0 == (key: "phone", value: "18888888888") 1 == (key: "age", value: 20) 2 == (key: "name", value: "zhangsan") 3 == (key: "height", value: 180) */Copy the code

Fourth, tuples

1, the introduction

Swift has a unique data structure that can be used to define a set of data, the data that makes up a tuple can be called an element

2, definitions,

Common writing

Var one = ("zhangsan", 20, "1888888888",180) // The types of the elements of this tuple are: String,Int,String,IntCopy the code

Give the element a name

Var one = (name: "zhangsan", age: 20, phone: "1888888888",height: 180Copy the code

3. Simple use

Use tuples to describe an HTTP error message

Print (error.0) print(error.1) print(error.1)Copy the code

ErrorCode: "Not Found" print(error.errorCode) print(error.errorinfo)Copy the code

Let (errorCode, errorInfo) = (404, "Not Found") print(errorCode) print(errorInfo)Copy the code

Combine, disassemble

// let httpError = (404,"NotFound") // let (str1,str2) = httpError print(" first argument is \(str1)") print(" second argument is \(str2)") // let httpStatus = httpError print(str3,_) = httpError print(" str3 is \(str3)") // Let httpStatus = \(httpstatus.status)") print(" des: \(httpstatus.status)") print(" des: \(httpstatus.des)")Copy the code