learn xcode and swift

letorangesAreOrange=truelet turnipsAreDelicious=false When we write conditional statements, such as the IF statement, the Boolean value is very useful1 if turnipsaredelicious {2 3 print ("Mmm,tasty turnips!") 4 5} else {6 7 print ("Eww,turnips is horrible. ") 8 9}//output" Eww, turnips is horrible. " 10 11 Meta-groupTuples combine multiple values into a single composite value. The values within a tuple can be any type and do not require the same typeLet Http404error = (404,

those years, learn the pits that Swift trod The recent learning of Swift, I thought that many of the grammar and OC are different, and are using the same cocoa framework, the same API, but more or less still some pits in, in order to avoid the next step, write down here, later found a new pit, will slowly be added here [TOC] where's the 1.main file? the code i

A few days ago to learn the next Tabbar, with you to share the study content, welcome everyone to make suggestions.As a beginner, there is no customization involved. There is no code involved.1. First drag a tab to the controller to the interface650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M02/6D/76/wKiom1VkmWuxcWcDAADU7yt25nc147.jpg "title=" 1.jpg " alt= "Wkiom1vkmwuxcwcdaadu7yt25nc147.jpg"/>2. You can see that

= {(A:int,b:int), Int in return a + B} (10,5) print ("Ten + 5 =\ (C1)")Explanation: Give C1 assignment, followed by a closure expression. However, the closure expression cannot be assigned directly to C1because C1 is of type Int and the return value of the closure is required. This requires that a pair of parentheses (10,5)be followed by the curly braces at the end of the closure, with the parentheses (10,5) passing the parameters for the closure. Welcome to follow Dongsheng Sina Weibo@tony_Do

line unless there is a very clear need.We find that each volume is prefixed with a let or var keyword, so what type are they? In fact, the swift language has a type inference mechanism (Tyoe inference), that is, by initializing the value to infer the actual type of the volume, for example, in the above example, two is inferred by Swift as an int type, you can use the option key to see the amount of the rea

Learn Swift from scratch (Day 52)-Cocoa error handling modeThe Swift error handling mode is different in Swift1.x and Swift 2.0. The error handling mode of Swift 1.x Code adopts the Cocoa framework error handling mode. Currently, Objective-C still adopts this mode, while the

Closures in Swift are equivalent to blocks in OC, and its purpose is to wrap a piece of code that can be invoked when necessary.　Closure definition :{(Type list), return value inMore than one swift statementExecute Code Insert Coding}The actual closure code is created as follows:1 inch 2 // code block 3 if value1>value2{4 return value15 } 6 return value2 7 8 }Note: 1. Here we define

This is a creation in Article, where the information may have evolved or changed. Original link: http://www.itproportal.com/features/go-ruby-swift-and-java-is-it-time-to-learn-a-new-devops-language/ Students of all ages have been encouraged (and even asked) to learn multiple languages. But the recent major impact is neither French nor Latin. Forget the accent

call wrapper is asserted at run time, so that no error is thrown. If the error is actually thrown, a run-time error is triggered.Enum Customerror:errortype {case someerror}func willonlythrowiftrue (value:bool) throws { If value {throw Custo Merror.someerror}}do { try Willonlythrowiftrue (true)} catch { print ("Error")}try! Willonlythrowiftrue (True) //Run-time errorFinishing ActionUse the defer statement to execute a series of statements. This allows you to perform some necessa

the program is not validA case can be matched with multiple objects, separated by commas:Switch Anothercharacter {case "B", "C", "D": println ("Output BCD") case "a", "E", "F": println ("Output AEF") Default: println ("not Found") the}//program outputs: Output AEFBecause when executing the program, compared with the three objects in the first case, we find that we do not want it, and then we execute the second case and compare it with the multiple objects.Tuples in switch are used:Writ

characters similar to identifiers. Defined by the language itself. You can't use it for him. Unless you enclose it with an accent sign ('). Swift language Common keyword have the following 4 species. keyword related to the declaration: class , Deinit , enum and so on. break Span style= "font-family: Arial" >, case , continue expression and type keyword: as catch , dynamictype , false keyword used in a specific context

discarded after the decimal point.Variable varVariables are declared with Var. After the declaration can be modifiedvar v = 20v = 30But note that you can only change the same type. With object-oriented thinking, the initialization is equivalent to birth, and after a pig is born you can't make him a person ... Can't just become a person can change that is eight commandments ...Tip, we cannot copy the string type to the int type, which means that Swift

simple.Accessing properties with optional chained callslet someAddress = Address()someAddress.buildingNumber"29"someAddress.street"Acacia Road"john.residence?.address = someAddressInvoking a method with an optional chained callifnil { print("It was possible to print the number of rooms."else { print("It was not possible to print the number of rooms.")}Access subscript via optional chained calljohn.residence?[0] = Room(name"Bathroom")To access the subscript for an optional typevar testScor

model, each country must have the capital, each city must belong to a country. This allows the two properties to be accessed directly after initialization (no optional expansion is required), while avoiding circular references. To meet this requirement, the Capitalcity property of country is declared as an implicit parsing of an optional type's property by adding an exclamation point (city!) at the end of the type. This means that, like other optional types, the default value of the Capitalcity

struct or enumeration's properties in a specific method, you can choose the mutation (mutating) method, and the method can change its properties from within the method, and any changes it makes will remain in the original structure at the end of the method. The method can also assign an entirely new instance to its implied self property, and the new instance will replace the original instance after the method finishes. struct PointS {var x = 0.0, y = 0.0 mutating func movebyx (deltax:dou

Daoerror:errortype {case NoData case Primarykeynull}NoData indicates no data condition, Primarykeynull represents the primary key of the table ( Primary Key ) is an empty case. Then we can catch the error with the following code.Do {//try accesses a data table function or method} catch Daoerror.nodata {print ("no data. ")} catchdaoerror.primarykeynull {print (" PRIMARY key is empty. ")}Welcome to follow Dongsheng Sina Weibo@tony_Dongsheng. Learn abou

("onclickwithextsender:forevent:") } for the purposes of data encapsulation, we will add the above method to Private to make it a private method, as shown in the code below. Private func OnClick (sender:anyobject) {NSLog ("OnClick:")}However, the following error occurs when the method is called:Unrecognized selector Sentto instance 0X7F7F81499B10 'This error means that the method specified by the selector is not found, that is, no OnClick: method. It is a good practice to add @objc attribute co

framework type. These data types areFoundationthere are corresponding data types in the framework, and these data types also have someSwiftThe native data type has a corresponding relationship. Watermark/2/text/ahr0cdovl2jsb2cuy3nkbi5uzxqv/font/5a6l5l2t/fontsize/400/fill/i0jbqkfcma==/dissolve/70/gravity /center "/>SeeSwiftnative type and Core FoundationExamples of conversions between types:Import Corefoundationimport Foundation var cfstr1:cfstring = "Hello,world" //Create cfstring string va

]/ /return 915699632[5] //return 615699632[6] //Return 5Nested TypesExtensions can add new nested types to existing classes, structs, and enumerations:Extension Int { enum Kind {case negative, Zero, Positive } var kind:kind { switch self {case 0: return. Zero case let number where number > 0: return. Positive Default: return. Negative } }}func printintegerkinds (numbers: [Int]) {for number in

object. The sample code is as follows:Let Host:cfhost =cfhostcreatewithname (Kcfallocatordefault, "127.0.0.1"). Takeretainedvalue () Let hostnames: Cfarray =cfhostgetnames (host, nil)!. Takeunretainedvalue ()Welcome to follow Dongsheng Sina Weibo@tony_Dongsheng. Learn about the latest technical articles, books, tutorials and information on the public platform of the smart Jie classroom650) this.width=650; "title=" 00.png "src=" http://s3.51cto.com/wy