oc--single Case--nsdate--archive--json--plist--protocol

-Single Case--------

Definition: A class allows only one object to be created, and this object can only be used whenever an object method or property is invoked anywhere. Note: In general, only limited class methods are created in the Singleton class.

Function: 1. A class can have only one object, and access it from a well-known access point 2. Save value

1. Set the objects of this class to static so that the object's uniqueness is guaranteed.

The Manage is a global

static Setupmanage *manage = nil;

+ (Setupmanage *) sharedmanage{

@synchronized (self) {//2 sync settings to ensure thread safety

3. If the object is empty, create an object

if (manage = = nil) {

manage = [[Setupmanage alloc]init];

}

}

4. Return the Created object

return manage;

}

Strictly speaking, we also want to rewrite the Allocwithzone: method when we call Alloc, the internal actually calls the Allocwithzone: method

+ (ID) Allocwithzone: (Nszone *) zone{

if (manage = = nil) {

manage = [Super Allocwithzone:zone];

}

return manage;

}

Releasing an object of a singleton

-(void) freemanage{

if (Manage! = nil) {

Manage = nil;

}

}

----------nsdate-----------

Gets the current system time direct output time GMT (GMT)

NSDate *date = [NSDate Date];

Output local time

(Nstimeinterval) is measured in seconds

NSDate *nowdate = [date datebyaddingtimeinterval:60*60*8];

NSLog (@ "%@,%@", date,nowdate);

Some time in the future 4001-01-01 00:00:00

NSDate *future = [NSDate distantfuture];

Some time in the past 0001-12-30 00:00:00

NSDate *past = [NSDate distantpast];

NSLog (@ "%@,%@", future,past);

Time comparison

NSDate *date1 = [NSDate Date];

if ([date isequaltodate:date1]) {NSLog (@ "Time");        }else{NSLog (@ "Time is different"); }

-------NSDateFormatter: A time converter, which converts a string to a nsdate type of data in a specified format as standard

Create an object of type NSDateFormatter

NSDateFormatter *formatter = [[NSDateFormatter alloc]init];

@ "1985-09-02 23:12:12"

Determine the standard

HH means 24-hour HH means 12-hour system

Formatter. DateFormat = @ "Yyyy-mm-dd HH:mm:ss";

NSDate *date = [NSDate Date];

Convert a date to a string

NSString *string = [Formatter stringfromdate:date];

String converted to date

NSDate *newdate = [Formatter datefromstring:string];

----------Archive------------

Archive: A way to store data, note: To implement archiving, you must comply with the Nscoding protocol

Divided into two types: 1. Archiving of classes of Systems 2. Archiving of custom Classes

----------json parsing-----------

NSString *string = [NSString stringwithcontentsoffile:@ "/users/desktop/shared Data/jsonuserlist.txt" encoding: Nsutf8stringencoding Error:nil];

NSLog (@ "%@", string);

Parsing with the JSON parser that comes with OC

First parameter: data to be parsed

Second parameter: (nsjsonreadingoptions)

Nsjsonreadingmutablecontainers = (1UL << 0), the top layer is a dictionary or an array

Nsjsonreadingmutableleaves = (1UL << 1), the top layer is a string

Nsjsonreadingallowfragments = (1UL << 2) The top layer cannot be a dictionary or an array

NSData *data = [string datausingencoding:nsutf8stringencoding];

Analytical

Nsdictionary *dic = [nsjsonserialization jsonobjectwithdata:data options:nsjsonreadingmutablecontainers Error:nil];

NSLog (@ "dic%@", dic[@ "Count"]);

------------plist-------------

Plist: The nsdictionary,nsarray,nsnumber,bool,nsstring content is stored.

In most cases the outermost is the dictionary

Role: Store properties, attribute-level storage.

1. Locate the plist file and find the path

NSString *path = @ "/users/qianfeng/desktop/myinfo.plist";

2. Create an empty dictionary

Nsmutabledictionary *dictionary = [[Nsmutabledictionary alloc]init];

3. Add Data

[Dictionary setobject:[nsnumber Numberwithint:4] forkey:@ "age"];

[Dictionary setobject:[nsnumber Numberwithchar: ' C '] forkey:@ "symbol"];

[Dictionary setobject:@ "Lilei" forkey:@ "name"];

[Dictionary setobject:@[@ "Chinese", @ "中文版"] forkey:@ "score"];

4. Writing data to the plist file

The second argument: if you write halfway, something else happens, you can't continue, and the finished part is retained.

[Dictionary Writetofile:path Atomically:yes];

Read

Dictionary = [nsdictionary dictionarywithcontentsoffile:path];

------------Protocol----------------

1. What is the definition of the agreement?

A list of methods is called a protocol. Features: Only the declaration of the method is not implemented. Implementation put in: that class refers to this Protocol, implementation is placed in the implementation of this class

2. Format: @protocol protocol name

Declaration List of methods

@end

3. Use of the Agreement:

3.1 Creating an agreement 2. Introduction of Protocol 3. Reference protocol Note: You are to abide by this Agreement 4. The implementation of the method in the writing protocol

4. Classification of agreements: informal agreements and formal agreements

4.1 Informal agreements: declarations of classes, declarations of member variables, declarations of methods only

Formal agreement: An official name was given to the agreement.

Difference: Informal agreement: can only be referenced by itself and subclass, formal agreement: As long as this class references me, you can use my

5. Why use the agreement? (Using Engineering: Understanding Protocol)

Provides a unified interface. When multiple classes have the same function, we can extract this function to form a list of methods.

6. Classification of internal methods of formal agreements

6.1 The method that is modified by @optional is quoted, this class can write the implementation of the method, also can not write the method implementation

6.2 When a method modified by @required is referenced, the class must write the implementation of the method (the default is the required type

7. Agreement and inheritance

Inheritance: protocol

Same point: All can provide a unified interface

Different points: Creating a parent class for an existing class without creating a separate class

There can be a declaration of a member variable within a method declaration

Coupled high coupling is relatively lower than inheritance

A sibling relationship between classes and classes can be any class, provided that only

To comply with this agreement, you can

8. Other functions

A protocol can be referenced by multiple classes or protocols

A class or protocol can reference multiple protocols at the same time

The Declaration of a Protocol and class can be placed at the same time. In the file

------------Anonymous Object--------------

Dog *DOG1 = [[Dog alloc]init];//real name object: There is an object pointer pointing to this object

[[Dog alloc]init];// Anonymous object : An object that has no object pointer pointing to

oc--single Case--nsdate--archive--json--plist--protocol