ios - 两张图看NSOperation

• NSOperation几个词搞清就算是了解了"基本"

  • 1.操作,两种创建操作的方法
  • 2.队列.把操作放到队列执行任务.
  • 3.操作之间关系设置(操作依赖)
  • 4.NSOperationQueue的特点:暂停.取消,继续

• 看测试代码如下:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

//创建队列
    NSOperationQueue * queue = [[NSOperationQueue alloc] init];
    
//创建操作方式一
    NSInvocationOperation * op1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(testOp1) object:nil];
    
//创建操作方式二
    NSBlockOperation * op2 = [NSBlockOperation blockOperationWithBlock:^{

            NSLog(@"Op2 -----%@",[NSThread currentThread]);
    }];


//以下几个操作是为了方便演示
    NSBlockOperation * op7 = [NSBlockOperation blockOperationWithBlock:^{

            NSLog(@"Op7 -----%@",[NSThread currentThread]);
    }];
    NSBlockOperation * op5 = [NSBlockOperation blockOperationWithBlock:^{

            NSLog(@"Op5 -----%@",[NSThread currentThread]);
    }];
    NSBlockOperation * op6 = [NSBlockOperation blockOperationWithBlock:^{

            NSLog(@"Op6 -----%@",[NSThread currentThread]);
    }];
    
    NSInvocationOperation * op3 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(testOp3) object:nil];
    NSInvocationOperation * op4 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(testOp4) object:nil];

    NSLog(@"mainQueue - %@",[NSThread currentThread]);
    
    /** 
     1.最大并发数是10,但是同时执行的操作的线程只有5个例如线程number 2~6.则:
     2.其余两个任务(op)执行时所在的线程可能在上面的线程,也可能不在上面的线程.
     */

//设置最大并发数
    queue.maxConcurrentOperationCount = 10;
    
//将操作op添加到创建的队列queue,还有一个方法是直接添加操作数组也可以
    [queue addOperation:op1];
    [queue addOperation:op2];
    [queue addOperation:op3];
    
    /** 
     1.线程依赖 
     2.op1总是在op2前面执行
     3.要避免循环依赖
     */
    [op1 addDependency:op2];
    
    
    [queue addOperation:op4];
    [queue addOperation:op5];
    [queue addOperation:op6];
    [queue addOperation:op7];
    
    
}

• 看图

NSOperationQueue.png

• 一下是测试op操作的方法.

-(void)testOp4{
    
        NSLog(@"op4---%@",[NSThread currentThread]);
}

-(void)testOp3{

        NSLog(@"op3---%@",[NSThread currentThread]);
}

-(void)testOp1{

        NSLog(@"op1------%@",[NSThread currentThread]);
}

@end

---

整体思路图:

NSOperation.png