直接上代码 --> 各种线程的创建方式
/// 创建异步队列
dispatch_queue_t async = dispatch_queue_create("async_queue", DISPATCH_QUEUE_CONCURRENT);
/// 创建同步队列
dispatch_queue_t sync = dispatch_queue_create("sync_queue", DISPATCH_QUEUE_SERIAL);
/// 创建主队列
dispatch_queue_t main_queue = dispatch_get_main_queue();
/// 全局并发队列
dispatch_queue_t global_queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
/// 同步
dispatch_sync(global_queue, ^{
});
/// 异步
dispatch_async(global_queue, ^{
});
线程创建的6中方式
第一种 --> 同步并发(从上往下依次执行，没有开启新线程) 在当前线程中执行任务，不会开启新线程，执行完一个任务，再执行下一个任务
| 执行结果 --> 添加至主线程执行先执行begin最后执行end，依次执行
- (void)syncConcurrentThread
{
NSLog(@"同步并发---begin %@",[NSThread currentThread]);
dispatch_queue_t sync = dispatch_queue_create("syncConcurrent", DISPATCH_QUEUE_CONCURRENT);
dispatch_sync(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncConcurrent = 1--%@",[NSThread currentThread]);
}
});
dispatch_sync(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncConcurrent = 2--%@",[NSThread currentThread]);
}
});
dispatch_sync(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncConcurrent = 3--%@",[NSThread currentThread]);
}
});
NSLog(@"同步并发---end %@",[NSThread currentThread]);
}
执行结果：
同步并发---begin {number = 1, name = main}
syncConcurrent = 1--{number = 1, name = main}
syncConcurrent = 1--{number = 1, name = main}
syncConcurrent = 1--{number = 1, name = main}
syncConcurrent = 2--{number = 1, name = main}
syncConcurrent = 2--{number = 1, name = main}
syncConcurrent = 2--{number = 1, name = main}
syncConcurrent = 3--{number = 1, name = main}
syncConcurrent = 3--{number = 1, name = main}
syncConcurrent = 3--{number = 1, name = main}
同步并发---end {number = 1, name = main}
第二种 --> 异步并发(开启多个新线程，任务随机接近同时执行) 可以开启多个线程，任务同时随机执行
| 执行结果 --> 先执行主线程代码(begin，end)，在执行子线程代码，并随机执行
- (void)asyncConcurrentThread
{
NSLog(@"异步并发---begin %@",[NSThread currentThread]);
dispatch_queue_t sync = dispatch_queue_create("syncConcurrent", DISPATCH_QUEUE_CONCURRENT);
dispatch_async(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncConcurrent = 1--%@",[NSThread currentThread]);
}
});
dispatch_async(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncConcurrent = 2--%@",[NSThread currentThread]);
}
});
dispatch_async(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncConcurrent = 3--%@",[NSThread currentThread]);
}
});
NSLog(@"异步并发---end %@",[NSThread currentThread]);
}
执行结果：
异步并发---begin {number = 1, name = main}
异步并发---end {number = 1, name = main}
asyncConcurrent = 1--{number = 3, name = (null)}
asyncConcurrent = 3--{number = 4, name = (null)}
asyncConcurrent = 2--{number = 5, name = (null)}
asyncConcurrent = 1--{number = 3, name = (null)}
asyncConcurrent = 3--{number = 4, name = (null)}
asyncConcurrent = 2--{number = 5, name = (null)}
asyncConcurrent = 1--{number = 3, name = (null)}
asyncConcurrent = 3--{number = 4, name = (null)}
asyncConcurrent = 2--{number = 5, name = (null)}
第三种 --> 同步串行 (任务依次执行，没有开启新线程) 不会开启新线程，在当前线程执行任务。任务是串行的，执行完一个任务，再执行下一个任务
| 执行结果 --> 先执行主线程的代码(begin,end)，在加入主线程依次执行
- (void)syncSerialThread
{
NSLog(@"同步串行---begin %@",[NSThread currentThread]);
dispatch_queue_t sync = dispatch_queue_create("syncConcurrent", DISPATCH_QUEUE_SERIAL);
dispatch_sync(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncSerial = 1--%@",[NSThread currentThread]);
}
});
dispatch_sync(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncSerial = 2--%@",[NSThread currentThread]);
}
});
dispatch_sync(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncSerial = 3--%@",[NSThread currentThread]);
}
});
NSLog(@"同步串行---end %@",[NSThread currentThread]);
}
执行结果：
同步串行---begin {number = 1, name = main}
syncSerial = 1--{number = 1, name = main}
syncSerial = 1--{number = 1, name = main}
syncSerial = 1--{number = 1, name = main}
syncSerial = 2--{number = 1, name = main}
syncSerial = 2--{number = 1, name = main}
syncSerial = 2--{number = 1, name = main}
syncSerial = 3--{number = 1, name = main}
syncSerial = 3--{number = 1, name = main}
syncSerial = 3--{number = 1, name = main}
同步串行---end {number = 1, name = main}
第四种 --> 异步串行 (开启一个线程) 会开启新线程，但是因为任务是串行的，执行完一个任务，再执行下一个任务
| 执行结果 --> 先执行主线程(begin,end)，然后在新的线程依次执行任务
- (void)asyncSerialThread
{
NSLog(@"异步串行---begin %@",[NSThread currentThread]);
dispatch_queue_t sync = dispatch_queue_create("syncConcurrent", DISPATCH_QUEUE_SERIAL);
dispatch_async(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncSerial = 1--%@",[NSThread currentThread]);
}
});
dispatch_async(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncSerial = 2--%@",[NSThread currentThread]);
}
});
dispatch_async(sync, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncSerial = 3--%@",[NSThread currentThread]);
}
});
NSLog(@"异步串行---end %@",[NSThread currentThread]);
}
执行结果：
异步串行---begin {number = 1, name = main}
异步串行---end {number = 1, name = main}
asyncSerial = 1--{number = 4, name = (null)}
asyncSerial = 1--{number = 4, name = (null)}
asyncSerial = 1--{number = 4, name = (null)}
asyncSerial = 2--{number = 4, name = (null)}
asyncSerial = 2--{number = 4, name = (null)}
asyncSerial = 2--{number = 4, name = (null)}
asyncSerial = 3--{number = 4, name = (null)}
asyncSerial = 3--{number = 4, name = (null)}
asyncSerial = 3--{number = 4, name = (null)}
第五种 --> 同步执行 + 主队列 在主线程调用(卡死) 在其他线程调用(不会卡死，不会开启新线程，依次执行)
| 执行结果 --> 在主队列执行(卡死) 在子线程中(依次执行)
- (void)syncMainThread
{
NSLog(@"同步执行 + 主队列 ---begin %@",[NSThread currentThread]);
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_sync(main_queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncMain = 1--%@",[NSThread currentThread]);
}
});
dispatch_sync(main_queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncMain = 2--%@",[NSThread currentThread]);
}
});
dispatch_sync(main_queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"syncMain = 3--%@",[NSThread currentThread]);
}
});
NSLog(@"同步执行 + 主队列 ---end %@",[NSThread currentThread]);
}
执行结果：
---begin {number = 1, name = main}
第六种 --> 异步执行 + 主队列 在主线程中依次执行
| 执行结果 --> 先执行主线(begin,end)，然后依次执行任务
- (void)asyncMainThread
{
NSLog(@"异步执行 + 主队列 ---begin %@",[NSThread currentThread]);
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_async(main_queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncMain = 1--%@",[NSThread currentThread]);
}
});
dispatch_async(main_queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncMain = 2--%@",[NSThread currentThread]);
}
});
dispatch_async(main_queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"asyncMain = 3--%@",[NSThread currentThread]);
}
});
NSLog(@"异步执行 + 主队列 ---end %@",[NSThread currentThread]);
}
执行结果：
异步执行 + 主队列 ---begin {number = 1, name = main}
异步执行 + 主队列 ---end {number = 1, name = main}
asyncMain = 1--{number = 1, name = main}
asyncMain = 1--{number = 1, name = main}
asyncMain = 1--{number = 1, name = main}
asyncMain = 2--{number = 1, name = main}
asyncMain = 2--{number = 1, name = main}
asyncMain = 2--{number = 1, name = main}
asyncMain = 3--{number = 1, name = main}
asyncMain = 3--{number = 1, name = main}
asyncMain = 3--{number = 1, name = main}
回到主线程
- (void)gobackMainQueue
{
/// 获取主队列
dispatch_queue_t mainQueue = dispatch_get_main_queue();
/// 获取全局并发队列
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
NSLog(@"begin----%@",[NSThread currentThread]);
dispatch_async(globalQueue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"continue----%@",[NSThread currentThread]);
}
});
dispatch_async(mainQueue, ^{
NSLog(@"mainQueue----%@",[NSThread currentThread]);
});
NSLog(@"end----%@",[NSThread currentThread]);
}
执行结果：
begin----{number = 1, name = main}
end----{number = 1, name = main}
continue----{number = 3, name = (null)}
continue----{number = 3, name = (null)}
continue----{number = 3, name = (null)}
mainQueue----{number = 1, name = main}
设置dispatch_barrier_async (线程障碍物)
- (void)setupBarrier
{
NSLog(@"begin----%@",[NSThread currentThread]);
dispatch_queue_t queue = dispatch_queue_create("queue", DISPATCH_QUEUE_CONCURRENT);
dispatch_async(queue, ^{
for (int i = 0; i < 2; i++) {
NSLog(@"one----%@",[NSThread currentThread]);
}
});
dispatch_async(queue, ^{
for (int i = 0; i < 2; i++) {
NSLog(@"two----%@",[NSThread currentThread]);
}
});
dispatch_async(queue, ^{
for (int i = 0; i < 2; i++) {
NSLog(@"three----%@",[NSThread currentThread]);
}
});
dispatch_barrier_async(queue, ^{
for (int i = 0; i < 2; i++) {
NSLog(@"barrier----%@",[NSThread currentThread]);
}
});
dispatch_async(queue, ^{
for (int i = 0; i < 2; i++) {
NSLog(@"four----%@",[NSThread currentThread]);
}
});
NSLog(@"end----%@",[NSThread currentThread]);
}
执行结果:
begin----{number = 1, name = main}
end----{number = 1, name = main}
three----{number = 4, name = (null)}
two----{number = 5, name = (null)}
one----{number = 3, name = (null)}
two----{number = 5, name = (null)}
three----{number = 4, name = (null)}
one----{number = 3, name = (null)}
barrier----{number = 3, name = (null)}
barrier----{number = 3, name = (null)}
four----{number = 3, name = (null)}
four----{number = 3, name = (null)}
从上面结果可以看出，执行完barrier之前所有的代码之后，才会执行barrier代码，接着执行下面的代码,起到了先执行以及后执行的目的
dispatch_apply --> GCD 中的快速迭代，在串行队列中，是和for循环一样的一次循环，在并行异步中，是在多个(最多9个)线程中执行，当便利足够次数的时候，快速迭代还是不如for循环时间
- (void)dispatch_apply
{
NSLog(@"执行开始");
for (long i = 0; i < count; i++) {
}
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_apply(count, queue, ^(size_t index) {
NSLog(@"----%@",[NSThread currentThread]);
});
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"执行完成");
});
}
执行结果：count足够大的时候，dispatch_apply非常缓慢
队列组 dispatch_group_t 待所有任务执行完成之后才会执行dispatch_group_t，可以回到主线程执行任务
- (void)dispatch_group_t
{
/// 创建一个队列组
dispatch_group_t group = dispatch_group_create();
/// 创建一个并行队列
dispatch_queue_t queue = dispatch_queue_create("queue", DISPATCH_QUEUE_CONCURRENT);
dispatch_group_async(group, queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"1---%@",[NSThread currentThread]);
}
});
dispatch_group_notify(group, queue, ^{
NSLog(@"notify-----%@",[NSThread currentThread]);
});
dispatch_group_async(group, queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"2---%@",[NSThread currentThread]);
}
});
}
执行结果:
1---{number = 3, name = (null)}
2---{number = 4, name = (null)}
2---{number = 4, name = (null)}
1---{number = 3, name = (null)}
2---{number = 4, name = (null)}
1---{number = 3, name = (null)}
notify-----{number = 3, name = (null)}
线程阻塞
- (void)dispatch_group_t
{
/// 创建一个队列组
dispatch_group_t group = dispatch_group_create();
/// 创建一个并行队列
dispatch_queue_t queue = dispatch_queue_create("queue", DISPATCH_QUEUE_CONCURRENT);
dispatch_group_async(group, queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"1---%@",[NSThread currentThread]);
}
});
/// 线程阻塞方法
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
dispatch_group_async(group, queue, ^{
for (int i = 0; i < 3; i++) {
NSLog(@"2---%@",[NSThread currentThread]);
}
});
dispatch_group_notify(group, queue, ^{
NSLog(@"notify-----%@",[NSThread currentThread]);
});
}
执行结果:
1---{number = 3, name = (null)}
1---{number = 3, name = (null)}
1---{number = 3, name = (null)}
2---{number = 3, name = (null)}
2---{number = 3, name = (null)}
2---{number = 3, name = (null)}
notify-----{number = 3, name = (null)}
1任务执行完之后，才会执行2任务
/// dispatch_group_enter、dispatch_group_leave
- (void)dispatch_group_enter_leave
{
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_enter(group);
dispatch_async(queue, ^{
for (int i = 0; i < 2; ++i) {
NSLog(@"1---%@",[NSThread currentThread]);
}
dispatch_group_leave(group);
});
dispatch_group_enter(group);
dispatch_async(queue, ^{
for (int i = 0; i < 2; ++i) {
NSLog(@"2---%@",[NSThread currentThread]);
}
dispatch_group_leave(group);
});
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
for (int i = 0; i < 2; ++i) {
NSLog(@"3---%@",[NSThread currentThread]);
}
});
}
执行结果： 相当于 dispatch_group_async
1---{number = 3, name = (null)}
2---{number = 4, name = (null)}
1---{number = 3, name = (null)}
2---{number = 4, name = (null)}
3---{number = 1, name = main}
3---{number = 1, name = main}