iOS GCD

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- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view.

//1、GCD是最简单的一种多线程实现方式、同时也是执行效率最高的一种方式，（全部是用 c语言代码编写的 API），也是苹果公司最推崇的一种多线程实现方式。

//2、 GCD也是通过 queue 来实现多线程

//3、GCD里面有俩种 queue，一种是串行队列：serial queue ;还有一种是并行队列：

//-------------------------------------------------------------//

//serial queue（串行队列）特点：第一个任务执行完毕，第二个任务才可以开始，依次类推一个任务要开始，必须要等到上一个任务结束才可以开始。

//serial queue 有俩种获取方式

//第一种获取方式：里面的任务是在主线程依次去执行:dispatch_queue_t queue = dispatch_get_main_queue();

//第二种方式：自己创建的队列，第一个参数是队列的名字（苹果推荐使用反向域名去命名），第二个参数队列的类型（串行队列、并行队列）,这种方式创建的队列，它会自己去开辟一个子线程去完成队列里面的任务 dispatch_queue_t queue = dispatch_queue_create("com.lanou3g.mySerialQueue", DISPATCH_QUEUE_SERIAL);

//-------------------------------------------------------------//

//并行队列--concurrent queue，特点：第一个任务开始之后，第二个任务不等第一个任务执行完毕就开始执行，依次类推，后边任务的执行跟前面没有关系。（先执行的任务不一定先执行完，最后执行的任务也不一定最后执行完），并行队列会根据队列里面的任务数量、cpu使用情况、内存消耗情况，开辟最合适的线程数量去完成队列里面的任务

// 并行队列也有两种创建方式

// 第一种方式 dispatch_queue_t oneQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

// global queue 是苹果里面的全局队列,有4个优先级DISPATCH_QUEUE_PRIORITY_DEFAUL, DISPATCH_QUEUE_PRIORITY_HIGH, DISPATCH_QUEUE_PRIORITY_LOW, DISPATCH_QUEUE_PRIORITY_BACKGROUND

// 第一个参数就是队列的优先级，第二个参数是苹果预留的参数为了以后去使用，目前没有用到，填写0

// 第二种创建并发队列的方式： dispatch_queue_t twoQueue = dispatch_queue_create("com.lanou3g.myQueue", DISPATCH_QUEUE_CONCURRENT);

//-------------------------------------------------------------//

self.view.backgroundColor = [UIColor whiteColor];

UIButton *serialButton = [UIButton buttonWithType:UIButtonTypeSystem];

serialButton.frame = CGRectMake(100,100, 100,100);

serialButton.backgroundColor = [UIColor blueColor];

[serialButton setTitle:@"串行" forState:UIControlStateNormal];

[serialButton setTitleColor:[UIColor yellowColor] forState:UIControlStateNormal];

[self.view addSubview:serialButton];

[serialButton addTarget:self action:@selector(clickSerial) forControlEvents:UIControlEventTouchUpInside];

UIButton *concurrentButton = [UIButton buttonWithType:UIButtonTypeSystem];

concurrentButton.frame = CGRectMake(100,220, 100,100);

concurrentButton.backgroundColor = [UIColor blueColor];

[concurrentButton setTitle:@"并行" forState:UIControlStateNormal];

[concurrentButton setTitleColor:[UIColor yellowColor] forState:UIControlStateNormal];

[self.view addSubview:concurrentButton];

[concurrentButton addTarget:self action:@selector(clickConcurrent) forControlEvents:UIControlEventTouchUpInside];

UIButton *backButton = [UIButton buttonWithType:UIButtonTypeSystem];

backButton.frame = CGRectMake(50,50, 50,50);

[backButton setTitleColor:[UIColor redColor] forState:UIControlStateNormal];

[backButton setTitle:@"Back" forState:UIControlStateNormal];

[self.view addSubview:backButton];

[backButton addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];

}

- (void)back {

[self dismissViewControllerAnimated:YES completion:nil];

}

//串行

- (void)clickSerial {

//第一种方式

dispatch_queue_t queue = dispatch_get_main_queue();

dispatch_async(queue, ^{

NSLog(@"小明出生了");

});

dispatch_async(queue, ^{

NSLog(@"小明长大了");

});

dispatch_async(queue, ^{

NSLog(@"小明结婚了");

});

dispatch_async(queue, ^{

NSLog(@"小明有娃了");

});

dispatch_async(queue, ^{

NSLog(@"小明老了");

});

dispatch_async(queue, ^{

NSLog(@"小明挂墙上了");

});

//第二种方式

dispatch_queue_t queue = dispatch_queue_create("小明的一生", DISPATCH_QUEUE_SERIAL);

dispatch_async(queue, ^{

NSLog(@"小明出生了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明长大了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明结婚了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明有娃了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明老了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明挂墙上了");

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

});

}

//并行

- (void)clickConcurrent {

//第一种方式

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

dispatch_async(queue, ^{

NSLog(@"小明出生了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明长大了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明结婚了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明有娃了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明老了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明挂墙上了");

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

});

//第二种方式

dispatch_queue_t queue = dispatch_queue_create("小明的一生", DISPATCH_QUEUE_CONCURRENT);

dispatch_async(queue, ^{

NSLog(@"小明出生了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明长大了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明结婚了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明有娃了");

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

});

dispatch_async(queue, ^{

NSLog(@"小明有孙子");

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

});

dispatch_async(queue, ^{

NSLog(@"小明老了");

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

});

//GCD中的group

dispatch_queue_t queue = dispatch_queue_create("12345", DISPATCH_QUEUE_CONCURRENT);

dispatch_group_t group = dispatch_group_create();