iOS Black Horse programmer--arc

Strong pointers: By default, all pointers are

is a strong pointer type (strong) in Arc

, an object that has no strong pointer reference

Then it will be recovered by the system.

Weak pointers: Weak pointers do not affect the collection of objects

In Arc, all the manual memory management

None of the related methods can call for example

Dealloc cannot override the parent class (cannot

Super Dealloc)

__weak defines a weak pointer

__weak person * p2 = p//weak pointer

Does not affect the object

A strong pointer reference uses the OC object type,

@property (Nonatomic,strong)

We use other people's projects, it's possible to use right and wrong

ARC's Project

-fno-objc-arc

-f-objc-arc

Third-party framework: is the project written by others,

We're going to use if he's a non-arc mechanism that gives

The compiler adds a parameter-fno-objc-arc

is to tell the compiler that this file is a non-arc machine.

So that no error is made, and the non-

Arc Manual memory Management method can be normal

Called to introduce an arc machine in a non-ARC project

File, add a parameter to the compiler-

F-bojc-arc, is to tell the compiler this article

is the arc mechanism.

Edit->refactor-convert to

ARC Circular Reference problem

If a circular reference problem occurs in the ARC mechanism

, you just have to turn it into a reference,

Weak weak pointers can solve problems

Block type

int bool Char float double

NSObject * ID SEL

Their common feature is the ability to define changes

Amount

1.int a = 0;

BOOL B = YES;

2. As a function, and the method of passing parameters

(void) test (int) A

Block: Is a more specific type of data in OC

That is used to encapsulate a piece of code and can

Pass this code as a parameter

1. Encapsulating code with {}

1.void Test (): The return value is empty, and no

Have parameter {}

^{};

2.int test (), with a return value, and a parameter

Number

^{return 10;}

3.int Test (int a); there is a return value, and a

A parameter

^ (int a) {return a + 1}

4.int Test (int a,int b) has a return value, with

Multiple parameters

1. Define a return value of NULL, and No

The block variable of the parameter

void (^myblock) () = ^{};

2. Define a return value, and there is no

The block variable of the parameter

Int (^myblock) () = ^{return

10;};

3. Define a return value, and there is a

The block variable of the parameter

Int (^myblock) (int a) = ^ (int

A) {return a + 1};

4. Define a return value, and there are multiple

The block variable of the parameter

Int (^myblock) (int a,int b) =

^ (int a,int b) {return a + B}

The advantage of block is that I define block

itself can not care

Implementation of block internal algorithm

Who calls the method that has the block parameter, who is

Give me the block internal algorithm.

Agreement

Protocols are used to declare methods.

@protocol MyProtocol

-(void) test;

@end

Methods in implementing the Protocol in. m

@required indicates that the following methods must implement

-(void) test1;

@optional represents an optional implementation

-(void) test2;

Optional, it's not in the class that complies with the protocol.

Inside display

However, required will prompt you to

Is

The protocol itself, he can follow other protocols.

Protocols can follow multiple

Base protocol

Protocols are used to declare methods.

@protocol MyProtocol

<NSObject>

Internal Declaration method

@end

Constraints of methods within an agreement

@required the methods that must be implemented

@optional Select the implementation

The default method is the one that must be implemented

Having a class follow the protocol requires only the class to inherit

Back < Agreement name >

Class can follow multiple protocols < protocol names, and the protocol

Name, protocol name >

The agreement itself may also be subject to other agreements < agreements

Name >

Member variables cannot be declared in the protocol

The subclass inherits the parent class and also inherits the parent

The protocols that the class follows

NSObject * obj = [[NSObject]

INIT];

ID obj2= [[nsobject alloc] init];

When you define an OC object variable, you can add

A protocol constraint

Person<myprotocol> *p =

[[Person alloc] init];

@property (Nonatomic,strong)

car<myprotocol2> * CAR;

If you want to qualify an object, be sure to

Agreement, then we generally use

Id<myprotocol2>obj to define

@property (Nonatomic,strong) ID

<Myprotocol2> obj;

Just like the @class function, it tells the class

, MyProtocol is an agreement

@protocol MyProtocol;

Declare the protocol to a. h file of a class,

Other classes of inheritance, there is no way to follow this

An agreement.

Define the protocol individually as a. h, any class

Can follow this agreement,

This article is from the "Ten Years" blog, please be sure to keep this source http://yanshinian.blog.51cto.com/8275527/1564567

iOS Black Horse programmer--arc