NSThread
- (void)viewDidLoad {
[super viewDidLoad];
//在子线程上执行
//第一种方法:
[NSThread detachNewThreadSelector:@selector(demoFunc) toTarget:self withObject:nil];
//第二种方法:
[self performSelectorInBackground:@selector(demoFunc2) withObject:nil];
//在主线程上执行
//waitUntilDone: 等待执行完子线程里面的内容再执行后面的
[self performSelectorOnMainThread:@selector(demoFunc) withObject:nil waitUntilDone:NO];
NSLog(@"主线程");
}
- (void)demoFunc{
NSLog(@"子线程");
}
- (void)demoFunc2{
NSLog(@"第二子线程");
}
队列
简单的添加线程
注: 队列产生的线程不会根据任务总数来生成，一个线程可能会执行多个任务
//新建队列
NSOperationQueue *queue = [NSOperationQueue new];
//任务
NSBlockOperation *blockOp = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"子线程1");
}];
//讲任务添加到队列
[queue addOperation:blockOp];
//在队列里直接添加任务
[queue addOperationWithBlock:^{
NSLog(@"子线程2");
//将任务添加到主线程
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
NSLog(@"主线程2");
}];
}];
NSLog(@"主线程1");
设置线程最大个数和取消任务执行
NSMutableArray *ops = [NSMutableArray array];
for (int i = 0; i < 100; i++) {
NSLog(@"------> %d", i);
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"i = %d", i);
}];
[ops addObject:op];
}
NSOperationQueue *queue = [NSOperationQueue new];
//设置线程的最大个数,若为1就会一个个的依次执行
queue.maxConcurrentOperationCount = 1;
[queue addOperations:ops waitUntilFinished:NO];
NSLog(@"主线程");
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
//队列里的任务执行取消
[queue cancelAllOperations];
});
给线程添加依赖关系，使其有序
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"子线程1");
}];
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"子线程2");
}];
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"子线程3");
}];
NSOperationQueue *queue = [NSOperationQueue new];
[queue addOperations:@[op1, op2, op3] waitUntilFinished:NO];
//添加依赖关系，先执行op1然后执行op2再执行op3
[op2 addDependency:op1];
[op3 addDependency:op2];
NSLog(@"主线程");
C方法
简单的主线程和子线程
//获取主队列
dispatch_queue_t mainQueue = dispatch_get_main_queue();
//按照默认优先级获取子队列
dispatch_queue_t subQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
//在主线程异步执行
dispatch_async(mainQueue, ^{
NSLog(@"主线程2");
});
//在子线程异步执行
dispatch_async(subQueue, ^{
NSLog(@"子线程");
});
NSLog(@"主线程1");
dispatch_async(queue, ^{
NSData *data = [NSData dataWithContentsOfURL:[NSURL url]];//....
UIImage *image = [UIImage imageWithData:data];
dispatch_async(dispatch_get_main_queue(), ^{
//如果要给界面赋值，应该在主线程上操作
[UIImageView new].image = image;
});
});
自定义串行队列(serial)
//自定义串行队列: 在同一个子线程依次执行
dispatch_queue_t customQueue = dispatch_queue_create("xuqian.queue1", DISPATCH_QUEUE_SERIAL);
for (int i = 0; i < 100; i++) {
dispatch_async(customQueue, ^{
NSLog(@"i = %d", i);
});
}
NSLog(@"主线程");
自定义并行队列(concurrent)
dispatch_queue_t queue = dispatch_queue_create("franfkan.queu3", DISPATCH_QUEUE_CONCURRENT);
dispatch_async(queue, ^{
NSLog(@"1");
});
dispatch_async(queue, ^{
NSLog(@"2");
});
dispatch_async(queue, ^{
NSLog(@"3");
});
NSLog(@"done");
死锁
NSLog(@"hello world");
//同步执行主队列，造成死锁
dispatch_sync(dispatch_get_main_queue(), ^{
NSLog(@"wellcome");
});
NSLog(@"=====");
创建组队列, 执行完所有内容发出通知(子线程里执行网络请求)
//自定义并行队列
dispatch_queue_t customQueue = dispatch_queue_create("xuqian.queue", DISPATCH_QUEUE_CONCURRENT);
//创建组
dispatch_group_t group = dispatch_group_create();
//创建信号量(用于子线程里执行网络请求)
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
dispatch_group_async(group, customQueue, ^{
NSLog(@"1");
dispatch_semaphore_signal(semaphore);
});
dispatch_group_async(group, customQueue, ^{
NSLog(@"2");
dispatch_semaphore_signal(semaphore);
});
dispatch_group_async(group, customQueue, ^{
NSLog(@"3");
dispatch_semaphore_signal(semaphore);
});
dispatch_group_async(group, customQueue, ^{
NSLog(@"4");
dispatch_semaphore_signal(semaphore);
});
//当组里面都执行完成以后(或者说当组为空时)然后在执行
dispatch_group_notify(group, customQueue, ^{
//四个请求对应四次信号等待
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"done");
});
栅栏
dispatch_async(queue, ^{
NSLog(@"1");
});
dispatch_async(queue, ^{
NSLog(@"2");
});
//拦截前面的，前面先执行完再执行后面的
dispatch_barrier_async(queue, ^{
NSLog(@"barrier");
});
dispatch_async(queue, ^{
NSLog(@"3");
});
dispatch_async(queue, ^{
NSLog(@"4");
});
