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//: Playground-noun:a Place where people can playImport UIKit//----The use of dictionaries------////A dictionary is a container that stores multiple elements of the same type//Each value is associated with a key, which is identified as the stored data in the dictionary//dictionaries are unordered.//Dictionary Limitations: KeyType must be hashed (hashable), providing a hash value so that the key can be identified. //1. Creation of dictionariesvarbooks:dictionary"Journey to the": +,"Kingdoms": $,"

()Maxpassengers= 5Numberofwheels= 4 }override func description () -> string { return super. () + ";" + "Traveling at \ (speed) mph" }} /span> In addition to overloading functions, the properties of a class can be overloaded in subclasses, such as the getter and setter methods:Class Speedlimitedcar: Car { Override VarSpeed: double { get { return . Speed } set { super.= Min (newvalue,40.0) } }} /span> Using a @final tag class, you can prohibit ov

Swift design mode: Prototype and swift design mode prototype Application scenarios:You need to copy the object to create a new object.Difficulties: Deep copy and light copy Initializing a class or structure consumes a lot of memory resources and computing resources. However, copying can save these resources.Copy of the value type is a deep copy.So how to implement deep copy for the reference type?The answe

Classes, structs, and enumerations can define subscripts, and he can quickly and easily access the elements of a collection (set,array,dict), and you can make use of subscripts to get and set the collection elements. You can define multiple subscripts for a type, which can be overloaded by the different index value types, and the number of indexed values may be multiple.GrammarLook at an example firstSubscript (index:int), Int { get { // return an appropriate Subscript valuehere }

original articles, welcome reprint. Reprint Please specify: Dongsheng's blog Swift 2.0 in the Print function has 4 kinds of overloaded forms: Print (_:). Output a variable or constant to the console, and wrap the line. print (_:_:). Outputs a variable or constant into a stream of the specified type, and wraps the line. print (_:appendnewline:) Output variable or constant to the console, appendnewline true represents a newline,

whether the value is found. The variable possibleintegervalue has an implicitly initialized nil value, so if an optional binding can determine success, possibleintegervalue changes The amount of four case in switch must set an actual value.In the above code example, Luo lists all possible characters that are not practical. Therefore, the case statement of Deafult handles all mismatches, and the default cases do nothing but use the break statement to end switch execution.Fallthrough ( landing )I

Unicode (Unicode code)Unicode is a text encoding of international standards. Its standard table contains almost any character of any language and can be read and written by extension files or Web pages.In Swift, string (string) and character (character) types are fully Unicode-compatible, and they also support non-Unicode codes.Unicode terminology (Unicode terminology)Each Unicode code can be represented by one or more Unicode scalars. For one charact

Optionals (optional type)When a value may have a value, there may also be no value, in which case you can use an optional type. The optional type means:There is a value that is equal to X, or that there is no value at all.Note the point:The concept of an optional type is not available in both C and OC. In the most similar case in OC, a method returns nil or returns an object. The return nil in OC means that there are no legitimate objects. However, this can only be for objects, not for structs,

with default values (extensions for defaults )In how many cases, it is necessary to provide the extension when using the default value for the parameter. This will clarify the meaning of the parameter, especially when calling the function.For convenience, Swift provides default parameters that are automatically extended to the definition when you do not provide an extension. This auto extension is the same as the local parameter name, as if you had w

function, just as you would with other types in swift. For example, you can define a constant or variable as the type of the function and assign a variable in the corresponding function:var mathfunction: (int, int), int = addtwointsThis code can be read as:"Defines a variable called mathfunction, which has a type of function, which takes two int values and returns an int value, and setting this variable requires referencing a function called addtwoin

First, mind mapSecond, the Code//This will make the code very ugly . ifX! = Nil Y! =Nil {print ("x or Y are not equal to null")} print ("x or Y has an empty") //1 use??Let name:string? ="I am the most handsome"Let age:int= - //?? Represents a selectable unpacking package//The following two execution results behave differently due to changes in values,Print (name??""+ String (age))//I'm the most handsome, because he has the lowest priorityPrint (name??"") + String (age))//I am the

following method requires the Somefunctionthattakesaclosure function pointer passed into the previous interface, Func initwithclosure (closure:sendvalueclosure?). {//Assign the function pointer to the Myclosure closure, which covers references to local variables in the somefunctionthattakesaclosure function myclosure = closure} init (Nibname nibn Ameornil:string, bundle Nibbundleornil:nsbundle?) {Super.init (Nibname:nibnameornil, Bundle:nibbundleornil)//Custom initialization} override func View

If you want to make a custom configuration, you can inherit the base class UIView.The map app needs to touch multiple touch more.Opaque non-transparentHidden hidden, such as the download of the progress bar, if downloaded, you can set this property to make the progress bar disappearClears graphics context If a view needs to update the content, you can check this property by clearing the previous contentClip Subview truncate the child view boundary if the child view of a view is a button, but thi

Swift keyword summary and swift keyword Summary There are four common keywords: Declaration-related keywords: class, deinit, enum, extension, func, import, init, let, protocol, static, struct, subscript, typealias, and var. Statement-related keywords: break, case, continue, default, do, else, fallthrough, if, in, for, return, switch, where, and while. Expression and type Keyword: as, dynamicType, is, ne

Build a binary tree (swift) and a binary tree swiftBuild a binary tree (swift) PublicclassALTree Var key: T? Var left: ALTree? Var right: ALTree? Func addNode (key: T ){ If (self. key = nil ){ Self. key = key Return } If (key If (self. left! = Nil ){ Left !. AddNode (key) } Else { Var leftChild: ALTree = ALTree () LeftChild. key = key Self. left = leftChild } } If (key> self. key ){ If (self. right! = N

[Swift learning] Swift programming tour-collection type Dictionaries (8), swiftdictionaries A dictionary is a storage that stores multiple types of data. Each value is associated with a unique key as the identifier of the value data in the dictionary. Unlike the data items in the array, the data items in the dictionary are not in specific order. Dictionary writing Dictionary Create an empty dictionary var

Application source code similar to "on demand" compiled by Swift, swift source code An App written in SwiftOverview This project was prepared to consolidate Swift's knowledge. The materials are from the official App Use Storyboard + Xib + Autolayout to implement the UI part Because the project is not complex, the directory structure is relatively simple. A module corresponds to a folder. There is

Swift UI special training 43 Swift APP boot page, swiftui When an APP is loaded for the first time, a boot page is usually used to show features or tell users how to use them. Open our Storyboard, import a Page View Controller, make the following settings, and modify the Transition Style: Set the storyboard ID to PageViewController for our Page View Controller. Now you should want to know how we can edit o

Swift social application text input optimization summary, swift social text SummaryI. Input-Related Optimization Problems In most applications, there is a need for input. In the face of a large number of users, their ideas vary, and the input text content is strange. In the face of different input, how should we optimize the input experience? Here we will summarize the Input-related questions, mainly as fol

Zhao yazhi _ Swift (4) _ asserted, Zhao yazhi _ swift asserted Optional. You can determine whether a value exists. You can optimize the processing of missing values in the code. However, in some cases, if the value is missing or does not meet specific conditions, your code may not need to be executed. In this case, you can trigger an assertion in your code to end code running and debug the code to find the