iOS中的串行,并行,分组,一次,障碍,延迟,反复执行(GCD)

#import "OneViewController.h"

@interface OneViewController ()

@end

@implementation OneViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark 方法
//依靠C语言来执行,效率最高

//串行队列
- (IBAction)serialBtn:(id)sender {
    //1.创建行对列
    
    //1.获取系统创建好的串行对列,在主线程中是实现线程同步
    dispatch_queue_t queue1 = dispatch_get_main_queue();
    
    
    //2.自己创建串行队列,任务在子线程中实现线程同步
    dispatch_queue_t queue2 = dispatch_queue_create("com.lanou3g.oa", DISPATCH_QUEUE_SERIAL); //字符串 -- 唯一标示的作用(反域名形式),DISPATCH_QUEUE_SERIAL -- 指定为串行
    //2.往队列中添加任务
    dispatch_async(queue2, ^{
        NSLog(@"任务一:%@",[NSThread currentThread]);
        
    });
    dispatch_async(queue2, ^{
        NSLog(@"任务二:%@",[NSThread currentThread]);
        
    });
    dispatch_async(queue2, ^{
        NSLog(@"任务三:%@",[NSThread currentThread]);
        
    });
    dispatch_async(queue2, ^{
        NSLog(@"任务四:%@",[NSThread currentThread]);
        
    });
    
    //释放
    dispatch_release(queue2);
    
}

//并行(并发)队列
- (IBAction)parallelBtn:(id)sender {
    //1.创建并发队列,系统创建好了四个
    //1.使用系统创建好的并发队列
    dispatch_queue_t queue1 = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); // 参数分别是:优先级,预留参数
    //2.自己创建并发队列
    dispatch_queue_t queue2 = dispatch_queue_create("com.lanou3g.oa", DISPATCH_QUEUE_CONCURRENT); // 参数1.唯一标示,参数二 指定为并发队列
    
    //3.往队列中添加任务
    dispatch_async(queue2, ^{
        NSLog(@"任务1: %@",[NSThread currentThread]);
    });
    
    dispatch_async(queue2, ^{
        NSLog(@"任务2: %@",[NSThread currentThread]);
    });
    dispatch_async(queue2, ^{
        NSLog(@"任务3: %@",[NSThread currentThread]);
    });
    dispatch_async(queue2, ^{
        NSLog(@"任务4: %@",[NSThread currentThread]);
    });
    //请求图片
    //跳转到主线程刷新界面
    dispatch_async(dispatch_get_main_queue(),^{
    //更新 UI 显示图片
    
    });
    //释放
    dispatch_release(queue2);
    
    
}

//分组任务
- (IBAction)groupBtn:(id)sender {
    //1.创建并行队列
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //2.创建分组
    dispatch_group_t group = dispatch_group_create();
    //3.方分组中添加任务
    dispatch_group_async(group, queue, ^{
        NSLog(@"任务一,请求 0 - 20 M数据");
    });
    dispatch_group_async(group, queue, ^{
        NSLog(@"任务二,请求 0 - 20 M数据");
    });
    dispatch_group_async(group, queue, ^{
        NSLog(@"任务三,请求 0 - 20 M数据");
    });
    dispatch_group_async(group, queue, ^{
        NSLog(@"任务四,请求 0 - 20 M数据");
    });
    dispatch_group_async(group, queue, ^{
        NSLog(@"任务五,请求 0 - 20 M数据");
    });
    //4.当分组内的所有任务完成之后,拼接操作
    dispatch_group_notify(group, queue, ^{
        NSLog(@"拼接数据吧!");
    });
    //释放
    dispatch_release(group);
}
//一次
- (IBAction)oneBtn:(id)sender {
}
//障碍
- (IBAction)obstacleeBtn:(id)sender {
    //障碍任务的作用:可以保证障碍之后的并发的任务,必须在障碍之前的并发的任务执行结束之后,才可以开始执行
    //注意:要添加障碍任务,必须要使用自己创建的并发队列.
    //创建并发队列
     dispatch_queue_t queue = dispatch_queue_create("com.lanou.3g.oa",DISPATCH_QUEUE_CONCURRENT);
    //往队列中添加任务
    dispatch_async(queue, ^{
        NSLog(@"A写入文件");
    });
    dispatch_async(queue, ^{
        NSLog(@"B写入文件");
    });
    dispatch_async(queue, ^{
        NSLog(@"C写入文件");
    });
    dispatch_async(queue, ^{
        NSLog(@"D写入文件");
    });
    //添加(设置)障碍任务
    dispatch_barrier_async(queue, ^{
        NSLog(@"此处是障碍任务");
    });
    dispatch_async(queue, ^{
        NSLog(@"读取文件");
    });
    //释放
    dispatch_release(queue);
}
//延迟
- (IBAction)delayBtn:(id)sender {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSLog(@"5秒,五秒");
        
    }); //dispatch_get_main_queue 在主线程中执行,如果想要在子线程中执行,此处改为子线程即可
    
}

//反复执行
- (IBAction)diReceiveMemoryBtn:(id)sender {
//    dispatch_apply(10, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(size_t index) {
//        NSLog(@"反复执行的次数:%ld,当前线程%@",index,[NSThread currentThread]);
//    });
    
    dispatch_apply(10, dispatch_get_main_queue(), ^(size_t index) {
        NSLog(@"反复执行的次数:%ld,当前线程%@",index,[NSThread currentThread]);
    });
}
@end

//单例

#import "Singleton.h"

@implementation Singleton
//+ (id)mainSingleton{
//    static Singleton *single = nil;
//    @synchronized(self){
//        if(!single){
//            single = [[Singleton alloc] init];
//        }
//        
//    }
//    return single;
//}

+ (id)mainSingleton{
static Singleton *single = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
    //写只执行一次的代码
    single = [[Singleton alloc] init];
});



return single;
}