网络多线程-GCD常用函数

#import "ViewController.h"

#import "XMGPerson.h"

@interface
ViewController ()

@end

@implementation ViewController

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

    /*

    XMGPerson *p1 = [[XMGPerson alloc]init];

    NSLog(@"%@",p1.books);

    

    XMGPerson *p2 = [[XMGPerson alloc]init];

    NSLog(@"%@",p2.books);

     */

    [self barrier];

}

//一次性代码:整个程序运行过程中只会执行一次

/*不能放在懒加载里面的*/

-(void)once

{

    NSLog(@"-----");

    static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{

        NSLog(@"----once----");

    });

}

//延迟执行

-(void)afterDelay

{

    NSLog(@"-----start----");

    

    //    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(run) userInfo:nil repeats:NO];

    

    //    [self performSelector:@selector(run) withObject:nil afterDelay:3.0];

    

    dispatch_queue_t queue =
dispatch_get_main_queue();

    //    dispatch_queue_t queue = dispatch_get_global_queue(0, 0);

    /*

     GCD里面的时间是以纳秒为单位的 1秒=10的九次方纳秒

     */

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0
* NSEC_PER_SEC)),queue , ^{

        

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

    });

}

//栅栏函数:控制并发队列里面任务的执行顺序

/*不能使用全局并发队列*/

-(void)barrier

{

    //1.创建并发队列

    dispatch_queue_t queue =
dispatch_queue_create("xmg",
DISPATCH_QUEUE_CONCURRENT);

    

    //2.异步函数

    dispatch_async(queue, ^{

        for (NSInteger i =
0; i<10; i++) {

            NSLog(@"download1--%zd--%@",i,[NSThread
currentThread]);

        }

    });

    

    dispatch_async(queue, ^{

        for (NSInteger i =
0; i<10; i++) {

            NSLog(@"download2--%zd--%@",i,[NSThread
currentThread]);

        }

    });

    

    //3.使用栅栏函数

    dispatch_barrier_async(queue, ^{

        NSLog(@"+++++++++++++++++barrier+++++++++++");

    });

    

    dispatch_async(queue, ^{

        for (NSInteger i =
0; i<10; i++) {

            NSLog(@"download3--%zd--%@",i,[NSThread
currentThread]);

        }

    });

    dispatch_async(queue, ^{

        for (NSInteger i =
0; i<10; i++) {

            NSLog(@"download4--%zd--%@",i,[NSThread
currentThread]);

        }

    });

    

    dispatch_async(queue, ^{

        NSLog(@"download5----%@",[NSThread
currentThread]);

    });

    

}

-(void)run

{

    NSLog(@"---run---");

}

@end