多线程NSOperation笔记

• NSOperationQueue属性

NSOperationQueue *queue = [[NSOperationQueue alloc] init];//创建队列
// 设置最大并发操作数
queue.maxConcurrentOperationCount = -1;//-1默认值不作限制,0为没有队列,1为串行队列,>1为并行队列
[queue cancelAllOperations];//取消所有的操作,为每个操作发送cancel,取消后不可恢复
queue.suspended = NO;//设置是否暂停(挂起)队列

@interface YQOperation : NSOperation
@end
@implementation YQOperation
//需要执行的任务
-(void)main{

for (NSInteger i = 0; i<1000; i++) {
    NSLog(@"download1 -%zd-- %@", i, [NSThread currentThread]);
}
//判断是否已经取消了操作
if (self.isCancelled) return;
for (NSInteger i = 0; i<1000; i++) {
    NSLog(@"download2 -%zd-- %@", i, [NSThread currentThread]);
}

}
@end

@interface ViewController ()
@end

@implementation ViewController
-(void)queue{

//创建队列
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
//创建操作(任务)
NSInvocationOperation *op1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(running) object:nil];
//创建操作(任务)
//一个正在执行的操作调用cancel方法,会执行完操作,可以在操作内用isCancelled判断
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
    //如果正在执行耗时操作时,操作被取消了(执行了cancel),本操作会执行完,可以用isCancelled检测....
    //检测到操作被取消,直接返回
    if (op2.isCancelled)return;
    
    NSLog(@"op2 --- %@", [NSThread currentThread]);
}];
//为op2追加操作(任务)
[op2 addExecutionBlock:^{
    NSLog(@"op2 ---Execution--- %@", [NSThread currentThread]);
}];

[queue addOperation:op1];
[queue addOperation:op2];
[queue addOperation:[YQOperation new]];
//创建操作(任务)
[queue addOperationWithBlock:^{
    NSLog(@"op3 --- %@", [NSThread currentThread]);
}];

}

-(void)running{

NSLog(@"running");

}
@end

设置依赖

执行结果:
download4----{number = 5, name = (null)}
download1----{number = 3, name = (null)}
download5----{number = 4, name = (null)}
download2----{number = 2, name = (null)}
op5执行完毕---{number = 4, name = (null)}
download3----{number = 2, name = (null)}
-(void)queue{

NSOperationQueue *queue = [[NSOperationQueue alloc] init];

NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
    NSLog(@"download1----%@", [NSThread  currentThread]);
}];
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
    NSLog(@"download2----%@", [NSThread  currentThread]);
}];
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
    NSLog(@"download3----%@", [NSThread  currentThread]);
}];
NSBlockOperation *op4 = [NSBlockOperation blockOperationWithBlock:^{
    sleep(0.5);
    NSLog(@"download4----%@", [NSThread  currentThread]);
}];
NSBlockOperation *op5 = [NSBlockOperation blockOperationWithBlock:^{
    NSLog(@"download5----%@", [NSThread  currentThread]);
}];
op5.completionBlock = ^{
    NSLog(@"op5执行完毕---%@", [NSThread currentThread]);
};

// 设置依赖后op1,op2,op4执行完成后才会执行op3
[op3 addDependency:op1];
[op3 addDependency:op2];
[op3 addDependency:op4];

[queue addOperation:op1];
[queue addOperation:op2];
[queue addOperation:op3];
[queue addOperation:op4];
[queue addOperation:op5];

}