Selector, jquery Selector

Selector, jquery Selector

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Selector

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[Recognition selector]

SEL

1. selector (SEL) is a variable type.

2. selector is used to load member messages (member method)

 

People * manInBlack = [[people alloc] init];

// SEL is a selector type, such as int a, int is an integer

// Create a selector sel, and sel installs the printName method in manInBlack.

SEL sel = @ selector (printName );

// Execution Selector

[ManInBlack performSelector: sel];

 

 

// Execute a selector method with Parameters

// A colon is added.

SEL sel1 = @ selector (printName :);

[ManInBlack performSelector: sel1 withObject: @ "I am a black man, I will be invisible"];

 

// [ManInBlack printName: @ "I grew up" withAge: @ "25"];

// Create a selector with two parameters

SEL sel2 = @ selector (printName: withAge :);

// Execute a selector with two parameters

[ManInBlack login mselector: sel2 withObject: @ "I grew up" withObject: @ "5 years old"];

// [Note] selector method, with a maximum of two parameters

 

Ii. Functions of Selector

1. selector supports ios development and event-related mechanisms.

2. selector can be used for method callback (proxy)

3. selector can implement multiple functions in another way to reuse code.

 

// Determine which method to call during compilation

SEL sel = @ selector (test1 );

 

// NSSelectorFromString can be used to determine which method to call at runtime

NSString * selectorStr = [NSString stringWithFormat: @ "test % d", I];

// NSSelectorFromString can convert string into SEL Method

// NSSelectorFromString is a system method that converts nsstring to SEL type.

SEL sel2 = NSSelectorFromString (selectorStr );

 

Iii. isKindofClass

[Note]

1. Use variables declared by SEL to install the member Method

2. Use variables declared by Class to install types

 

// Load the test method into the sel variable.

SEL sel = @ selector (test );

// Load the book type into the las variable

// Class: This is a type used to hold the Class.

Class las = [book class];

NSArray * array = @ [@ "one", @ "tow", mybook, @ "jack"];

// [Question] how to retrieve the book type variable from array

For (id object in array)

{

// IsKindOfClass is used to determine whether the object is of the book type.

// IsKindOfClass is used to determine which class the object belongs.

If ([object isKindOfClass: las]) {

NSLog (@ "% @", object );

}

}

 

[Dynamic creation class]

[Note] NSClassFromString can be used for dynamic creation. The retrieved class must be the class in the current project.

// Load an NSString type into the variable defined by the Class

// Tell the compiler to find the class named book. h book. m in the current project and convert it into a type. Convert to a book type

// Class mybook = NSClassFromString (@ "book ");

// Book * myFirstBook = [[mybook alloc] init];

NSMutableArray * tmpArr = [[NSMutableArray alloc] init];

NSArray * classNameArray = @ [@ "surperMan", @ "food", @ "book"];

For (int I = 0; I <3; I ++ ){

NSString * C_name = classNameArray [I];

// NSClassFromString returns the class corresponding to the string

// Prerequisite: The retrieved class must be the class in the current project. If the class does not exist in the current project

// Nil is returned.

// NSClassFromString can be used for dynamic creation

Class myClass = NSClassFromString (C_name );

Id obj = [[myClass alloc] init];

[TmpArr addObject: obj];

}

Dynamic Creation has many benefits.

1. greatly simplified the amount of code

2. Make the program more powerful

3. Saving program memory