GCD練習(xí)
ios 多線程 GCD ： ios 多線程
- 全劇隊列，異步執(zhí)行
- 線程間通信
- 信號量
- 文件鎖
- 單利模式
- 延時執(zhí)行
- 取消任務(wù)
- 多核心遍歷數(shù)組
- 隊列組
- 消息傳遞機制
0.關(guān)于隊列
1).創(chuàng)建或獲取隊列
// 獲取全劇隊列，并發(fā)隊列
//第一個參數(shù)為：優(yōu)先級，第二個參數(shù)為：蘋果保留參數(shù)，寫0即可。
#define DISPATCH_QUEUE_PRIORITY_HIGH 2
#define DISPATCH_QUEUE_PRIORITY_DEFAULT 0
#define DISPATCH_QUEUE_PRIORITY_LOW (-2)
#define DISPATCH_QUEUE_PRIORITY_BACKGROUND INT16_MIN
dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
// 獲取主隊列，串行隊列
dispatch_queue_t queue = dispatch_get_main_queue();
// 創(chuàng)建隊列 串行隊列（DISPATCH_QUEUE_SERIAL 或者 NULL），并發(fā)隊列（DISPATCH_QUEUE_CONCURRENT）
// 第一個參數(shù)為：隊列名字，第二個參數(shù)為：隊列類型，如上
dispatch_queue_t queue = dispatch_queue_create("name", DISPATCH_QUEUE_CONCURRENT)
1.全劇隊列，異步執(zhí)行
- (void)test7{
dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
for (int i = 0 ; i < 20; i++) {
dispatch_async(queue, ^{
NSLog(@"%@ - %d",[NSThread currentThread],i);
});
}
dispatch_suspend(queue);
}
2. 線程間通信
- (void)gcd{
dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
for (int i =0 ; i<self.dataArray.count; i++) {
// 異步添加操作到，全劇隊列
dispatch_async(queue, ^{
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:self.dataArray[i]]];
UIImage *img = [UIImage imageWithData:data];
UIImageView *imgView = (UIImageView *)_imgViewArray[i];
imgView.image = [UIImage new];
// 回到主線程更新UI
dispatch_async(dispatch_get_main_queue(), ^{
imgView.image = img;
});
});
}
}
3. 信號量
1).信號量控制線程最大并發(fā)數(shù)量
- (void)test4{
dispatch_semaphore_t semaphore = dispatch_semaphore_create(10);//為了讓一次輸出10個，初始信號量為10
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
for (int i = 0; i <100; i++)
{
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);//每進來1次，信號量-1;進來10次后就一直hold住，直到信號量大于0；
dispatch_async(queue, ^{
NSLog(@"%i - %@",i,[NSThread currentThread]);
sleep(2);
dispatch_semaphore_signal(semaphore);//由于這里只是log,所以處理速度非常快，我就模擬2秒后信號量+1;
});
}
}
4. 文件鎖
- (void)test7{
// 必須傳DISPATCH_QUEUE_CONCURRENT，不然和dispatch_async一樣
dispatch_queue_t queue = dispatch_queue_create("kk", DISPATCH_QUEUE_CONCURRENT);
// dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
// 這里可以是異步讀文件
for (int i = 0; i<10; i++) {
dispatch_async(queue, ^{
NSLog(@"111 - %@ - %d",[NSThread currentThread],i);
});
}
// 只允許一個線程在，一個時間，修改數(shù)據(jù)
dispatch_barrier_async(queue, ^{
NSLog(@"%@ - 2222",[NSThread currentThread]);
});
// 其他線程異步讀取，修改后的數(shù)據(jù)
for (int i = 0; i<10; i++) {
dispatch_async(queue, ^{
NSLog(@"333 - %@ - %d",[NSThread currentThread],i);
});
}
}
5. 單利模式
static SingletonTimer * instance;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[SingletonTimer alloc] init];
});
return instance;
6. 延時執(zhí)行
- (void)test7{
dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC));
dispatch_queue_t queue = dispatch_get_main_queue();
dispatch_after(time, queue, ^{
NSLog(@"%@",[NSThread currentThread]);
});
}
7. 取消任務(wù)
- (void)test8{
dispatch_queue_t concurrentDispatchQueue = dispatch_queue_create("com.test.queue", DISPATCH_QUEUE_CONCURRENT);
dispatch_async(concurrentDispatchQueue, ^{
for (int i=0; i<100; i++)
{
NSLog(@"%i",i);
if (i==50)
{
NSLog(@"-----------------------------------");
dispatch_suspend(concurrentDispatchQueue);
sleep(3);
dispatch_async(dispatch_get_main_queue(), ^{
dispatch_resume(concurrentDispatchQueue);
});
}
}
});
}
// 我們甚至可以在不同的線程對這個隊列進行掛起和恢復(fù)，因為GCD是對隊列的管理。
8. 多核心遍歷數(shù)組
- (void)test11{
NSArray *arr = [[NSArray alloc] initWithObjects:@"1",@"2",@"3", nil];
dispatch_apply(arr.count, dispatch_get_global_queue(0, 0), ^(size_t i) {
NSLog(@"%@ - %zu",[NSThread currentThread],i);
});
NSLog(@"over %@",[NSThread currentThread]);
}
9. 隊列組
- (void)test9{
// dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t queueAll1 = dispatch_queue_create("hahaha1", DISPATCH_QUEUE_CONCURRENT);
dispatch_queue_t queueAll2 = dispatch_queue_create("hahaha2", DISPATCH_QUEUE_CONCURRENT);
dispatch_group_async(group, queueAll1, ^{
for (int i =0 ; i<10; i++) {
NSLog(@"%s - %d - %@",dispatch_queue_get_label(queueAll1),i,[NSThread currentThread]);
}
});
dispatch_group_async(group, queueAll2, ^{
for (int i =0 ; i<10; i++) {
[NSThread sleepForTimeInterval:1.0];
NSLog(@"%s - %d - %@",dispatch_queue_get_label(queueAll2),i,[NSThread currentThread]);
}
});
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
for (int i =0 ; i<10; i++) {
NSLog(@"%s - %d - %@",dispatch_queue_get_label(dispatch_get_main_queue()),i,[NSThread currentThread]);
}
});
}
10. 消息傳遞機制
- (void)test12{
//創(chuàng)建一個數(shù)據(jù)對象，DISPATCH_SOURCE_TYPE_DATA_ADD的含義表示數(shù)據(jù)變化時相加
source = dispatch_source_create(DISPATCH_SOURCE_TYPE_DATA_ADD, 0, 0, dispatch_get_main_queue());
//創(chuàng)建接收數(shù)據(jù)變化的句柄
dispatch_source_set_event_handler(source, ^{
NSLog(@"%lu",dispatch_source_get_data(source));
});
//啟動
dispatch_resume(source);
//設(shè)置數(shù)據(jù)
dispatch_source_merge_data(source, 2);
//這步執(zhí)行完之后會執(zhí)行打印方法
}
