IOS Multithreading (4) Nsoperation

2.NSOperation

• 2.1 Nsoperation Basic Use

(1) Related concepts

01 NSOperation是对GCD的包装02 两个核心概念【队列+操作】

(2) Basic use

01 NSOperation本身是抽象类，只能只有它的子类02 三个子类分别是：NSBlockOperation、NSInvocationOperation以及自定义继承自NSOperation的类03 NSOperation和NSOperationQueue结合使用实现多线程并发

(3) Related code

//Nsinvocationoperation    //1. Encapsulation Operations    / * First parameter: target object second parameter: The method to be called by the operation, which accepts a parameter of the third parameter: The parameter passed by the method is called, if the method does not accept the parameter, then the value is nil */Nsinvocationoperation *operation = [[Nsinvocationoperation alloc] Initwithtarget: SelfSelector@selector(Run) object:Nil];//2. Start Operation[Operation start];-------------------------------------------------//Nsblockoperation    //1. Encapsulation Operations    / * Nsblockoperation provides a class method that encapsulates the operation in this class of methods * /Nsblockoperation *operation = [Nsblockoperation blockoperationwithblock:^{//execute in main thread        NSLog(@"---download1--%@",[NsthreadCurrentThread]); }];//2. Append operation, append operation executed in child thread[Operation Addexecutionblock:^{NSLog(@"---download2--%@",[NsthreadCurrentThread]);    }]; [Operation Addexecutionblock:^{NSLog(@"---download3--%@",[NsthreadCurrentThread]); }];//3. Starting the execution action[Operation start];----------------------------------------------//03 Custom Nsoperation    //How to encapsulate the operation?     //Custom nsoperation, by overriding the internal main method for encapsulation operations-(void) Main {NSLog(@"--main--%@",[NsthreadCurrentThread]); }//How to use?     //1. Instantiating a custom Action objectXloperation *op = [[Xloperation alloc]init];//2. Performing Actions[op start];

• 2.2 Nsoperationqueue Basic use

(1) Two types of queues in nsoperation

01 主队列 通过mainQueue获得，凡是放到主队列中的任务都将在主线程执行02 非主队列 直接alloc init出来的队列。非主队列同时具备了并发和串行的功能，通过设置最大并发数属性来控制任务是并发执行还是串行执行

(2) Related code

//Custom Nsoperation-(void) customoperation{//1. Creating a queueNsoperationqueue *queue = [[Nsoperationqueue alloc]init];//2. Encapsulation Operations    //Benefits: 1. Information concealment    //2. Code ReuseXloperation *OP1 = [[Xloperation alloc]init]; Xloperation *OP2 = [[Xloperation alloc]init];//3. Adding actions to the queue[Queue ADDOPERATION:OP1]; [Queue addoperation:op2];}//nsblockoperation- (void) blockoperation{//1. Creating a queue       / * Concurrency: Global concurrent queue, create yourself (concurrent) Serial: Master queue, create it Yourself (serial) */    //Nsoperationqueue    /* Home column: All tasks placed in the main queue execute [nsoperationqueue Mainqueue] Non-host column: Alloc int with concurrent and serial functions, default is concurrent queue * /Nsoperationqueue *queue = [[Nsoperationqueue alloc]init];//2. Encapsulation OperationsNsblockoperation *OP1 = [Nsblockoperation blockoperationwithblock:^{NSLog(@"1----%@",[NsthreadCurrentThread]);    }]; Nsblockoperation *OP2 = [Nsblockoperation blockoperationwithblock:^{NSLog(@"2----%@",[NsthreadCurrentThread]);    }]; [Op2 addexecutionblock:^{NSLog(@"3----%@",[NsthreadCurrentThread]);    }]; [Op2 addexecutionblock:^{NSLog(@"4----%@",[NsthreadCurrentThread]); }];//3. Adding actions to the queue[Queue ADDOPERATION:OP1];    [Queue ADDOPERATION:OP2]; [Queue ADDOPERATION:OP3];//Supplement: A Simple method[Queue addoperationwithblock:^{NSLog(@"5----%@",[NsthreadCurrentThread]); }];}//nsinvocationoperation- (void) invocation{/ * Queues in GCD: Serial queue: Self-created (serial), Home queue concurrent queues: self-created (concurrent), global concurrent queue nsoperationqueue Home column: [nsoperation Queue Mainqueue]; actions placed in the main queue perform non-home columns in the main thread: [[[Nsoperationqueue Alloc]init], concurrent and serial, default is concurrent execution */    //1. Creating a queueNsoperationqueue *queue = [[Nsoperationqueue alloc]init];//2. Encapsulation OperationsNsinvocationoperation *OP1 = [[Nsinvocationoperation alloc]initwithtarget: SelfSelector@selector(Download1) object:Nil]; Nsinvocationoperation *OP2 = [[Nsinvocationoperation alloc]initwithtarget: SelfSelector@selector(download2) object:Nil]; Nsinvocationoperation *OP3 = [[Nsinvocationoperation alloc]initwithtarget: SelfSelector@selector(DOWNLOAD3) object:Nil];//3. Adding encapsulated operations to the queue[Queue ADDOPERATION:OP1];//[OP1 start][Queue ADDOPERATION:OP2]; [Queue addoperation:op3];}

• 2.3 Nsoperation Other uses

(1) Set maximum concurrent number "control task concurrency and serial"

//1.创建队列    NSOperationQueue *queue = [[NSOperationQueue alloc]init];    //2.设置最大并发数    //注意点：该属性需要在任务添加到队列中之前进行设置    //该属性控制队列是串行执行还是并发执行    //如果最大并发数等于1，那么该队列是串行的，如果大于1那么是并行的    //系统的最大并发数有个默认的值，为-1，如果该属性设置为0，那么不会执行任何任务    queue2;

(2) Suspension and recovery and cancellation

    //Set pause and resume    //suspended set to Yes to pause, suspended set to No for recovery    //Pause indicates that the next task in the queue is not resumed and the suspend operation can be resumed    if( Self. Queue. issuspended) { Self. Queue. Suspended=NO; }Else{ Self. Queue. Suspended=YES; }//Cancel all operations inside the queue    //Cancel, the next action of the currently executing operation will no longer execute, and will never be executed, as if all subsequent tasks were removed from the queue    //Cancel operation is not recoverable[ Self. QueueCancelalloperations];---------Custom nsoperation cancel Operation---------------------------(void) main{//time-consuming operation 1     for(inti =0; i< +; i++) {NSLog(@"Task 1-%d--%@", i,[NsthreadCurrentThread]); }NSLog(@"+++++++++++++++++++++++++++++++++");//Apple recommends that whenever a time-consuming operation is performed, the current queue is canceled, and if so, exit directly    //benefits can improve the performance of the program    if( Self. iscancelled) {return; }//time-consuming operation 2     for(inti =0; i< +; i++) {NSLog(@"Task 1-%d--%@", i,[NsthreadCurrentThread]); }NSLog(@"+++++++++++++++++++++++++++++++++");}

-2.4 nsoperation operation dependency and monitoring

  //1. Creating a queueNsoperationqueue *queue = [[Nsoperationqueue alloc]init]; Nsoperationqueue *queue1 = [[Nsoperationqueue alloc]init];//2. Encapsulation OperationsNsblockoperation *OP1 = [Nsblockoperation blockoperationwithblock:^{NSLog(@"1----%@",[NsthreadCurrentThread]);    }]; Nsblockoperation *OP2 = [Nsblockoperation blockoperationwithblock:^{NSLog(@"2----%@",[NsthreadCurrentThread]);    }]; Nsblockoperation *OP3 = [Nsblockoperation blockoperationwithblock:^{NSLog(@"3----%@",[NsthreadCurrentThread]);    }]; Nsblockoperation *OP4 = [Nsblockoperation blockoperationwithblock:^{NSLog(@"4----%@",[NsthreadCurrentThread]);    }]; Nsblockoperation *OP5 = [Nsblockoperation blockoperationwithblock:^{ for(NsintegerI=0; i<10000; i++) {NSLog(@"5-%zd---%@", i,[NsthreadCurrentThread]); }    }];//Monitor completeOp4. Completionblock= ^{NSLog(@"OP4 has finished---%@.",[NsthreadCurrentThread]); };//Add operation dependency, note cannot loop dependent[Op1 ADDDEPENDENCY:OP5]; [Op1 ADDDEPENDENCY:OP4];//Add action to queue[Queue ADDOPERATION:OP1];    [Queue ADDOPERATION:OP2];    [Queue ADDOPERATION:OP3];    [Queue ADDOPERATION:OP4]; [Queue1 ADDOPERATION:OP5];

(2) Download multiple picture synthesis case (set operation dependency)

//02 Comprehensive Case- (void) download2{NSLog(@"----");//1. Creating a queueNsoperationqueue *queue = [[Nsoperationqueue alloc]init];//2. Encapsulation operation download Picture 1Nsblockoperation *OP1 = [Nsblockoperation blockoperationwithblock:^{Nsurl*url = [Nsurlurlwithstring:@"Http://h.hiphotos.baidu.com/zhidao/pic/item/6a63f6246b600c3320b14bb3184c510fd8f9a185.jpg"]; NSData *data = [NSData Datawithcontentsofurl:url];//Get Picture data         Self. Image1= [UIImageImagewithdata:data]; }];//3. Encapsulation operation download Picture 2Nsblockoperation *OP2 = [Nsblockoperation blockoperationwithblock:^{Nsurl*url = [Nsurlurlwithstring:@"Http://pic.58pic.com/58pic/13/87/82/27Q58PICYje_1024.jpg"]; NSData *data = [NSData Datawithcontentsofurl:url];//Get Picture data         Self. Image2= [UIImageImagewithdata:data]; }];//4. Compositing picturesNsblockoperation *combine = [Nsblockoperation blockoperationwithblock:^{//4.1 Opening the graphics contextUigraphicsbeginimagecontext (Cgsizemake ( $, $));//4.2 painting Image1[ Self. Image1Drawinrect:cgrectmake (0,0, $, -)];//4.3 painting Image2[ Self. Image2Drawinrect:cgrectmake (0, -, $, -)];//4.4 get the picture data according to the graphic context        UIImage*image = Uigraphicsgetimagefromcurrentimagecontext ();//NSLog (@ "%@", image);        //4.5 Closing the graphics contextUigraphicsendimagecontext ();//7. Back to the main thread refresh UI[[Nsoperationqueue mainqueue]addoperationwithblock:^{ Self. ImageView. Image= Image;NSLog(@"Refresh UI---%@",[NsthreadCurrentThread]);    }]; }];//5. Setting Operation Dependencies[Combine ADDDEPENDENCY:OP1]; [Combine ADDDEPENDENCY:OP2];//6. Adding actions to the queue execution[Queue ADDOPERATION:OP1];    [Queue ADDOPERATION:OP2];    [Queue Addoperation:combine]; }

IOS Multithreading (4) Nsoperation