Swift Learning Day Fifth: string

Introduction to Strings

• Strings are used very frequently in any development.
• Differences between the strings in OC and Swift
  • When the string type is nsstring in OC, the string type in Swift
  • The string @ "" In OC, the string "" in Swift
• StringReasons for use
  • Stringis a structural body with higher performance
  • NSStringis an OC object with slightly poor performance
  • StringSupports direct traversal
  • SwiftProvides String NSString seamless transitions between and

Use of String Traversal string

// 字符串遍历var str = "Hello, Swift"for c in str.characters { print(c)}

string concatenation

• Concatenation of two strings

let str1 = "Hello"let str2 = "World"let str3 = str1 + str2

• Concatenation of strings and other data types

let name = "why"let age = 18let info = "my name is \(name), age is \(age)"

• Formatting of strings
  • such as time: 03:04

let min = 3let second = 4let time = String(format: "%02d:%02d", arguments: [min, second])

Interception of strings

• Special interception methods are available in Swift
  • The way is very troublesome
  • Index creation is more troublesome
• The simple way is to convert a string into NSString to use the
  • After the identifier, add: as NSString

Import UIKit//1. Define the string: Swift defines the string without @, directly a C-language string ""Let str ="Hello World"//2. Traversing characters in a string: A space is also considered a character forCinchstr.characters {print (c)}//3. Concatenation of strings//3.1. Stitching between StringsLet str1 ="Small size brother"Let str2="IT Education"Let result= str1 +str2//3.2. Stitching between strings and other identifiersLet age = -Let name=" Why"Let height=1.88//format for stitching other identifiers: \ (name of identifier)Let info ="my name is \ (name), age is \ (age), height is \ (height)"//3.3. String formatting:%02d represents the placeholder meaning, two bits, less than two bits of 0 to complement, arguments parameter type is an array, [Min, second] represents an array, swift array can hold the basic type of data, with [] to represent//Music Player:Let min =3Let second=GenevaLet timestr= String (format:"%02d:%02d", arguments: [min, second])//4. String interception: From and to are includedLet urlstring ="www.520it.com"//turn String type to NSString type string as NSStringLet Header = (urlstring asnsstring). substring (to:3) Let Middle= (urlstring asnsstring). Substring (With:nsrange (location:4, Length:5)) Let footer= (urlstring asnsstring). substring (from:Ten)

Swift Learning Day Fifth: string