iOS 10-GCD的常用方式

直接上代码、

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

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

//    [self delay];

//    [self once];

//    [self apply];

    [self group];

}

//延时操作的几种方式

-(void)delay {

    //使用NSObject 两秒后执行runing方法

    [self performSelector:@selector(runing) withObject:nil afterDelay:2];

    //GCD方式

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

        [self runing];

    });

    

    //使用NSTimer repeats:参数代表是否循环

    [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(runing) userInfo:nil repeats:NO];

    

    NSLog(@"########");

}

//执行的方法

-(void)runing {

    NSLog(@"runing!");;

}

//一次性操作  该代码只执行一次

-(void)once {

    static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{

        NSLog(@"一次性操作");

    });

}

//多次操作

-(void)apply {

    //执行10次操作

    dispatch_apply(10, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(size_t index) {

        //index 需要自己填写 每次遍历下标

        NSLog(@"---%ld----", index);

        /*

         从打印结果可以看出，与for循环不一样的是，该代码使用

         并行方式运行的，所以打印的下标不是按顺序。

         */

    });

}

//组操作

-(void)group {

    //创建组

    dispatch_group_t group = dispatch_group_create();

    dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

//        方便演示，添加个循环

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

            NSLog(@"任务1");

        }

        

    });

    

    dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

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

            NSLog(@"任务2");

        }

    });

    //当1.2完成后，再去执行3

    dispatch_group_notify(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSLog(@"任务3");

    });

}

@end