Swift classes and structures, storage properties, computed properties, functions and methods, subordinate scripts, etc.

Write 12 person to review, but to complete the same code need to hit the keyboard is a lot less than OC, which is due to the Swift does not write a semicolon, and less oc in brackets.

I. CLASS and Structure

There's not much difference between the two in Swift.

There are many similarities between classes and structs : ( 2, 3 points are not present in other languages )

1) You can define properties /Methods /subscripts (structs can also define methods )

2) can be initialized (by means of construction )

3) can use extension (extension) and Protocol (protocol)

4) Global Properties/methods in classes and structs (enumerations ) : In classes with the class keyword , but in structs with static

Multi-function analogy structure :

1) can Inherit

2) The type of class object can be checked at runtime

3) destructor Release resources

4) Reference counting allows a class instance to have multiple references

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2. Class person1{
4. var name = "Jack"
6. class var height:int = 10//Error! A class cannot have a global storage property, only a computed property. See note below
8. }
12. struct person2{ //struct more like a class in Java
14. var age:int
16. static var Height:int = 10//can set global properties and need to be initialized.
18. }
22. 1.1 Instantiating classes and structs, default constructors
24. Let P1 = Person1 ()
26. Let P2 = Person2 (age: Ten) //when using the default constructor, all of the properties inside must be initialized

Second, attribute (store attribute --COMPUTE attribute --Class attribute )

2.1 Store Properties : is to store a constant or variable , similar to a member variable in Java

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2. Class person3{
4. var name:string = "Xuneng" //Manual initialization required
6. var age:int = Ten
8. Let height = 175
10. Lazy var p1:person1 = Person1 () //delay, must be var
12. }
16. var p3 = Person3 ()
18. P3.name //access by DOT syntax
20. P3.age = One //set
24. Defer Lazy Store Properties: Initialize when using properties, the benefit of avoiding wasted space
26. println (P3.P1) //This is called when P1 is initialized

2.2 Computed Properties : Do not store values directly , but instead use get/set . To manipulate changes in other property values

Get: Take , the process used to encapsulate a value

Set: Set , used to encapsulate the process of setting a value

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2. Class person4{
4. var name:string = "Jack"
6. var jjlength:int = Ten
8. var age:int{ //can only be var
10. get{
12. return jjlength * 2
14. }
16. Set (NewAge) {
18. Jjlength = newage/ 2
20. }
22. }
24. }
26. var P4 = Person4 ()
28. P4.age = Ten //When set to age 10 o'clock, Jjlength becomes 5

2.2.1 Simple calculation of attribute notation

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2. Default parameter NewValue, which represents the newly assigned value
4. Class person5{
6. //With NewValue
8. var jjlength:int = Ten
10. var age:int{ //can only be var
12. get{
14. return jjlength * 2
16. }
18. set{
20. Jjlength = newvalue/ 2
22. }
24. }
28. //read-only computed properties
30. var height:int{
32. get{
34. return jjlength * 4
36. }
38. }
42. var height2:int{ //read-only direct can omit get
44. return jjlength * 4
46. }
48. }
52. var P5 = Person5 ()
54. P5.height
56. P5.height = 10//read-only cannot be assigned

2.2.2 Note the dead loop condition of the computed attribute

The value of the computed property is not fixed, so it cannot be decorated with a let and can only be used with var

Computed properties cannot be directly assigned to a value

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2. Class person6{
4. //With NewValue
6. var jjlength:int = Ten
10. var height2:int = 10{//cannot be assigned directly, otherwise it is stored as a property.
12. Return Jjlength * 4
14. //    }
18. var age:int{
20. get{
22. return age //Dead loop. Age calls the Get method
24. }
26. set{
28. Age = NewValue //Dead loop. The set method is called when the age value is set
30. }
32. }
34. }

Class 2.3 Attributes (or type attributes ) are decorated with the Class keyword . Class properties can only be computed properties .

A class property is a property similar to the static decoration in Java . A class has only one copy , and multiple instance objects are shared . Can be called directly with the class name

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1. Class person7{
2. class var name:string{
3. return "Xuneng"
4. }
5. }
6. Person7.name

2.4 Property Monitor: 2 methods that can be used to monitor property changes willset, Didset

Computed properties because of the get and set methods , the monitor is actually not very useful for calculating properties . Useful for storing properties

willset and Didset are not called when initializing a value

Willset, Didset and set, get cannot coexist

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2. Class person8{
4. var name:string = "Xuneng" {
6. willset{
8. println ("new value: \ (newvalue)") //newvalue new value
10. }
12. didset{
14. println ("new value is: \ (oldValue)") //oldvalue represents the old value
16. }
18. }
20. }
22. var P8 = Person8 ()
24. P8.name = "Jack" //This sentence is called

Three, function and method

3.1 Object Methods

The difference between a method in a class and a function : After the first argument of the method , it is all an external parameter . Name is the parameter name

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1. Class person9{
2. Func sum (num1:int, num2:int) {
3. println (NUM1 + num2)
4. }
5. }
6. var p9 = Person9 ()
7. P9.sum (num2: Ten) //After the first parameter, it is all external parameters. The equivalent of adding #

The 3.2 class method. Modify with class

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1. Class person10{
2. class func sum (Num1:int, num2:int) {
3. println (NUM1 + num2)
4. }
5. }
6. Person10.sum (Ten, num2: ten)

3.3 Self vs. super, same as OC

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1. Class person11{
2. Func sum (num1:int, num2:int) {
3. Self.fun () //Object method Call object method, class method call class method
4. }
6. Func Fun () {
7. println ("Hello")
8. }
9. }

Four, subscript (secondary script)

Subscript, Some are called subordinate scripts (subscript), new things.

Can be defined in the class /struct /enumeration for quick access.

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1. Format: You can also set Set/get
2. /*
3. Subscript (index:int), int{
4. get{
6. }
7. set{
9. }
10. }
11. */

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1. struct person12{   // The official structure of many   
2.     let jjLength:Int       //struct here can not initialize   
3.        
4.     subscript (index:int)  -> int{  
Li class= "alt" >         return jjlength  * index  
5.     }  
6. }   
7.   
8. var p12 = person12 (Jjlength: 10"   
9. p12[3]      //accesses the .   directly like an array, according to the JJ length, index is 3, and the value is 30  

See Example code: http://github.com/xn4545945/SwiftLearning

Reference:

The Swift programming Language

Apple Dev Center

Reprint Please specify source: http://blog.csdn.net/xn4545945

Swift classes and structures, storage properties, computed properties, functions and methods, subordinate scripts, etc.