OBJECTIVE-C Foundation

1.C language oriented process, OC object-oriented

2. First OC Program

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        NSLog(@"Hello, World!");
    }
    return 0;
}

1) Import introduces header file to prevent duplicate inclusion

2) Foundation/foundation.h file contains a lot of header files, introduced this is tantamount to the OC library files are cited.

3) @autoreleasepool

4) comparison between NSLog and printf

NSLog Wrap, printf does not

NSLog will output time and other project information, printf will not output debugging information

The argument to the NSLog function is a NSString object, and printf is a string constant pointer

Print the string with%@,nsstring *[email protected] "ANCC"; NSLog (@ "%@", str1);

[Email protected] "" represents a string

4. Documentation Comments

/**

*

**/

5. Enhanced for Loop

6. Definition of class

//
// main.m
// OC1
//
// Created by fanyafang on 15/10/30.
// Copyright © 2015 itcast. All rights reserved.
//

#import <Foundation / Foundation.h>

#pragma mark Person Class
@interface Person: NSObject
{
     @public
     int _age;
     NSString * _name;
}
     -(void) getAge;

@end


@implementation Person
     -(void) getAge {
         NSLog (@ "dddd");
     }
@end

#pragma mark

int main (int argc, const char * argv []) {
     @autoreleasepool {
         Person * p = [Person new];
         p-> _ age = 10;
         NSLog (@ "% d", p-> _ age); 

[P getage];

 } return0;}

7. Understanding of Memory

Code area: Store class definition, load once

Heap Area: Store case variables, save the address of the Code area class

Stack area: Storing objects

Usage of 8.NSString:

1) How to create a string

NSString *[email protected] "This is a string!";

NSString *s=[nsstring New];

NSString *imgname=[nsstring stringwithformat:@ "xxxxxxxx%02d.jpg", i];//format Create string

NSString *s2=[[nsstring Alloc] initwithstring:s1];//Create a new string with an existing string

2) output A string

NSLog (@ "%@", asstring);

3) String length calculation method

Using strlen function in C language

Nsuinterger len=[s1 length];//nsuinterger unsigned long integer in OC

1 Men by 1 lengths

9.OC Multi-file development

The header file and the class implementation file are written separately, with the import containing

10. Learning of class methods

11. Anonymous Class

To invoke a class method using an anonymous class: [[Car new] stop];

[Car new] is equivalent to [[Car alloc]init]

The advantages of an anonymous class: You can simplify the code and make it easier to call the method; disadvantage: The anonymous object is instantiated only once with the member variable correctly.

The writing of the 12.get-set method

13. Relationships between objects:

Combination (grape) dependency (one object's method parameter is another object) association (owned, the member of one class is an object of another class)

No overloads in 13.OC, class methods cannot have the same name

Usage of 14.static

1) Extend the life cycle of a variable in a method

2) defined in the implementation class, defined in the interface class, only valid in the previous file

Use of 15.self

1) In an object method, call another object method

2) in a class method, call another class method

3) modifier variable-in the Set method, the shape participates in the instance variable name equal, takes the instance variable with self

16. Inheritance

1) Variables that cannot be defined in the same way as the parent class

2) Single inheritance, does not support inheriting multiple classes

3) Support for multi-layer inheritance subclasses can also be inherited

17. Case Variable Modifiers

Public: Publicly available, also accessible in other classes

Protected: Protected type, accessible only in the current class and subclass

Private: cannot be accessed directly

Variables and methods that are not declared in the. h file are defined only in. m files and cannot be inherited and used

18.%@ the address of the Print object, the default calling object's description method, you can override this method

19. Polymorphism: The ability of different objects to respond to the same name method in their own way is called polymorphic

Parent class pointer to object of child class

20. The nature of the class is the class object

1) class C1=[d class]; Class C1=[D1 class]; if D and D1 are objects of the same class, that C1 and C2 point to the same address

2) Acquire the method, obtain class C1=[d class by the case object, and obtain the class C1=[dog class by its name;

3) Use of class object instead of class name new object

21.SEL [email protected] (test)//manually package the test method into SEL type

[P performselector:s1];//sends the SEL message to the test method, which is equivalent to [P test];

22. The essence of point syntax is to invoke getter, setter method, not access member variable

Object. Property =...;//replaced by the Set method

... = object. property;//Replace with Get method

Use of [email protected]

Written in the declaration file, equivalent to defining a get, set method declaration

 
#import <Foundation/Foundation.h> @interface Animal : NSObject
{ int _age;
}

@property int age; //-(void)setAge:(int)age; //-(int)age; @end

Use of [email protected]

Code written in the implementation file equivalent to the comment section

#import "Animal.h"

@implementation Animal

@synthesize age;

//-(void) setAge: (int) age {
// self-> age = age; // @ synthesize age will automatically create a new age instance variable
//}
//-(int) age {
// return self-> age;
//}

@end

@synthesize age=_age;//Specifies the case variable name and does not manipulate the default variable

Equivalent:

 
 
//-(void)setAge:(int)age{
//    _age=age;
//}
//-(int)age{
//    return _age; 
//}

After xcode4.4, you can use only @property instead of @systhesize, and you do not have to define an underscore variable

The action is a case variable with an underscore, and if the current class does not have an underscore case variable, then the system will generate it for us. Note that the variable is private (relative, hidden) subclasses do not see

@property enhanced, override the Get, set method in the. m file, but cannot override it at the same time, overriding only one

25. Dynamic type and static type

Dynamic type: A pointer to the parent class that points to the object of the child class

Static type:

The use of 26.id, ID is a universal pointer, can point to any object

Both NSObject and ID can point to any object

NSObject object is compile-time checked (requires coercion of type conversions)

ID does not need to force type conversion, ID can be used directly

After the compiler sees the ID, it is considered a dynamic type, not checked

ID Obj=[animal new];

27: Dynamic Binding

Introspection

Dynamic Type detection:

1) Type of judgment

1)) Determines whether an object is an instance object of a class, or a case object of a subclass

BOOL iskind = [ANI Iskindofclass:[animal class]]; (Objects and classes)

2)) To determine whether this class is a case, whether or not it is a subclass of this class

Ismemberof (objects and classes)

3)) Determine if the case is a subclass

Issubclassofclass

BOOL iskind = [Dog issubclassofclass:[animal class]];(classes and classes)

2) method Response detection

1)) Determines whether the object responds to the specified method:

Respondstoselector: Sel of the method

2)) Determines whether a class can respond to a specified method

Instanceresponsetoselector: Sel of the method

3) Response method

No reference:Performselector:sel

There is one parameter: Performselector:sel withobject:@ "parameter"

There are two parameters: Performselector:sel withobject:@ "parameter" withobject:@ "Parameter 2"

28. Constructor method Init, is an object method that returns an object-the object that invokes the Init method

29. Overriding the construction method

-(instancetype)init{
    self = [super init];
    if(self){
        _age=10;
    }
    return self;
}

OBJECTIVE-C Foundation