OC Study First day

OC First day 2016-3-14

Eg:1

#import <Foundation/Foundation.h>

Include header files in OC using #import

#import <Foundation/Foundation.h> representation: Contains the Foundation.h in the Foundation framework

Root class of Nsobject:oc

The suffix name of the OC implementation file is. m

Summarize the characteristics of the classes and methods inside the system

int main (int argc, const char * argv[]) {

@autoreleasepool {

Insert code here ...

NSLog (@ "Hello, world!"); /Implement Printing function

NSLog (@ "Hello, world!"); /has self-wrapping function.

int intvalue;

scanf ("%d", &intvalue);//Implement input data from the keyboard

NSLog (@ "intvalue:%d", intvalue);

char* p = "helloworld!";

NSLog (@ "p:%s", p);

The first parameter of NSLog: Formatting a string

The type to which the formatted string belongs is the NSString type, which is @ "Hello, world!" This is a string object

Declares a String object

nsstring* [email protected] "Helloworld-helloworld"; the object declared in//oc is a pointer

NSLog (@ "str:%@", str);//Output OC object, using the output format is%@

Declaring and initializing an object

nsstring* str1=[nsstring stringwithutf8string: "HELLO oc!"];

Converts a C string to a String object in OC (Initializes a string object in OC with a C string)

Use the form of a method in OC [object method name + argument list]

NSLog (@ "str:%@", str);

Equivalent

NSLog (@ "str:%@", [str description]);

%@ the output object, the compiler will callback the description method, and if the object belongs to a class that does not have the description method overridden, only the type and address can be output

NSLog (@ "str1:%@", str1);

printf ("Hello world!");

}

return 0;

}

Eg:2

1.c++ vs. OC: implementation file suffix name (. cpp. h); header file contains different preprocessing commands (#include #import)

#import可以防止头文件被重复包含 but still does not prevent cross-containment

To prevent cross-inclusion: use class in C + + to forward life; use @class in OC to make forward declaration

The basic structure of the 2.OC class definition

@interface Class Name: Parent class name

Member List

@end

3. Basic structure of class implementation

@implementation class Name

Implementation of members in a class

//

@end

4. Declaration of members in a class: instance variables (corresponding to C + + member variables) and methods (corresponding to C + + member functions)

The declaration of the instance variable is appended with "{//instance variable declaration}" after the parent class name

Declaration of the method, in the {//instance variable declaration} method declaration

#import <Foundation/Foundation.h>

@interface Mypoint:nsobject

{

Instance variable//default access permission is @pro tected

int x;

int y;

}

Method declaration

-(void) print;//implementation printing functions like non-static member functions in C + +

Method declaration format in OC:

-(return value type of the method) label name 1: (parameter 1 type) parameter 1 name label 2: (Parameter 2 type) Parameter 2 ...

Methods that begin with '-' are referred to as "instance methods."

-(void) SetX: (int) _x AndY: (int) _y;//Modify information

The declarative approach is to note that the number of colons is the same as the number of formal parameters. The method name consists of a label name and a colon (for example: Setx:andy:);

The first label name can not be omitted, other label names may be omitted

@end

int main (int argc, const char * argv[]) {

@autoreleasepool {

Insert code here ...

nsstring* [email protected] "Hello oc!";

NSLog (@ "str:%@", str);

Arrays in OC can only hold objects

nsnumber* Num=[nsnumber Numberwithint:10];

Convert basic data type int to OC object

NSLog (@ "nsnumber:%@", num);

//

nsnumber* num1=[nsnumber Numberwithchar: ' A '];

Convert basic data type char to OC object

NSLog (@ "nsnumber:%@", NUM1);

nsnumber* Num2=[nsnumber Numberwithbool:false];

NSLog (@ "%@", num2);

nsnumber* Num3=[nsnumber numberwithfloat:12.3];

NSLog (@ "%@", num3);

Nsinteger intvalues=20;//is not a class type, do not add *

nsnumber* Num4=[nsnumber Numberwithinteger:intvalues];

NSLog (@ "%@", NUM4);

NSLog (@ "Intvalues:%ld", intvalues);

addresscard* card=[[addresscard alloc]initwithname:@ "Tom" andemail:@ "[email protected]"];

NSLog (@ "Hello, world!");

}

return 0;

}

#import <Foundation/Foundation.h>

@interface Mypoint:nsobject

{

Instance variable

int x;

int y;

}

-(ID) INITWITHX: (int) _x AndY: (int) _y;

-(void) print;

-(NSString *) description;

-(void) SetX: (int) _x AndY: (int) _y;//Modify information

@end

@implementation MyPoint

-(void) print

{

NSLog (@ "x:%d, y:%d", X, y);

}

-(void) SetX: (int) _x AndY: (int) _y

{

x=_x;

y=_y;

}

-(ID) INITWITHX: (int) _x AndY: (int) _y

{

if (self = [super init]) {

x=_x;

y=_y;

}

return self;

}

Overriding the Description method

-(NSString *) description

{

nsstring* p=[nsstring stringWithFormat: @ "x:%d, y:%d", X, Y];

return p;

}

@end

int main (int argc, const char * argv[]) {

@autoreleasepool {//

mypoint* P=[[mypoint alloc] initwithx:1 andy:2]; Alloc equivalent to New in C + + opens heap space init: Initialization method (function to initialize instance variables in heap space)//The object itself is a pointer

Alloc: Application heap Space if the application heap space is successful, the OC instantiation object is returned (that is, the first address of the return heap space).

NSLog (@ "%@", p);//What if the content of the P object needs to be output? Overriding the description method in the P-owning class

Overriding: Defining a method in a derived class that is the same as the base class prototype, the derived class overrides the method of the base class

[P print];//[] is a salient feature of the message mechanism [receiver message]

Receiver: Message's recipient message: Messages

[P print]; Send a print message to the object p. The compiler searches for a method with the same name as the message in the P-owning class, and finds the execution

How do I disable the ARC mechanism (automatic reference counter mechanism)?

buildsettings--Search bar Search language--language objective c--objective-c antomatic Reference counting Change the value of this key to No

[P release];

NSLog (@ "\ n");

}

return 0;

}

OC Study First day